Bejo Nuvance | Oppiplaas 11

01/2020

VOLUME

11

oppiplaas

’N VOLLEDIGE JOERNAAL VAN DIE NUVANCE GROENTESAAD-PRODUKREEKS A COMPREHENSIVE JOURNAL OF THE NUVANCE VEGETABLE SEED PRODUCT RANGE

| www.nuvance.co.za |

34

38 19 NUUS | NEWS

BEDRYF | INDUSTRY

01 new(vance) website 03 dutch-based bejo acquires south

15

african distributor nuvance

NAVORSING | RESEARCH

05 11

brassica stunting disease (BSD) update bacterial canker and wilt in fresh market tomatoes

19 23 25

impressions of the northern cape onion industry bees and bejo: natural partners in seed production hydroponic greenhouse plant populations for tomato production in the eastern cape estimating vegetable crop water use

index

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editorial Editor Dr Q Muhl T: 012 943 0724 E: q.muhl@nuvance.co.za

Layout and design Y Botha T: 082 5787 547 E: yvonne@karbonmedia.co.za

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Publisher Nuvance (Pty) Ltd

PRODUKTE | PRODUCTS

STREEKSNUUS | REGIONAL NEWS

32 33 34 35 38

40 40

hoplita komkommer – die regte keuse is pH perhaps the culprit?

verwelkoming: lindie oberholzer verwelkoming: de wet meyer

bejo visits clearwater farms maragogi presteer weer in die noorde sentinel sukses

Disclaimer: The information in this newsletter is presented in good faith and Nuvance (Pty) Ltd. does not accept any legal liability in terms thereof. Disease resistances referred to in this newsletter are indicative of the cultivar’s tolerance, not its resistance. Varieties listed throughout this newsletter, marked with *, indicate that the cultivar is currently undergoing trials and will thereafter be considered to be submitted for registration. The product information and descriptions in this newsletter are correct at the time of going to press. Pictures displayed in this newsletter only indicate the kind and not the actual specific variety.

new(vance) website

W

e wanted to make our website faster, easier to navigate, and more user-friendly and so we are pleased to announce the launch of our brand-new website www.nuvance.co.za.

After several months of hard work and dedication, we are delighted to officially announce the launch and share all the exciting features we’ve prepared for you.

The new website features a minimalistic design style with plenty of navigation elements that help you to find the information they need. One of the main new features is a custom search/filter function, enabling you to refine the search results of a particular category listing, e.g. by crop, type, growth habit or disease profile.

Multiple filters may be applied to take a broad range of crops/cultivars and refine them into a narrower

selection, allowing you to retrieve the most relevant search results based on the criteria you’ve selected.

‘Our goal with this new website is to provide you with an easier and quicker way to find the information you need.’

Large images and short descriptions of our varieties make it easy to navigate between your search results, while all the technical information sheets of our commercial vegetable varieties are now available for

2

news article by dr quintin muhl

download (in pdf format) directly from the website.

We will continue to update our content with helpful information, articles, newsletters, company announcements and client successes, so make sure to check in with us often. Digital versions of our Oppiplaas magazine have also been added for your online reading convenience. This popular publication brings you the latest news, views and success stories while keeping you up to date with the challenges facing the vegetable grower’s community.

For more information about our regional branches and sales representatives in your area please feel free to visit our Contact page.

‘We hope you find it easy to access the information and other valuable resources on our new website.’

For any questions, suggestions, feedback or comments, please feel free to contact us at info@nuvance.co.za.

dutch-based bejo acquires south african distributor nuvance

B

ejo and Zaad Holdings are pleased to announce Bejo’s acquisition of Nuvance, as of July 1st 2020. Until June 30th Nuvance was a subsidiary of Klein Karoo Seed Marketing, part of Zaad Holdings.

Bejo is a Dutch family-owned company specialized in international breeding, production and sales of vegetable seed.

Nuvance is a well-established South African seed supplier with extensive expertise in Sub-Saharan Africa, ‘proudly in Africa for Africa’. The two companies have worked together for numerous years in developing South African horticulture and share a dedication for the professional vegetable market.

Recent socio-economic changes across the African continent are driving a growing demand for locally produced, high quality, healthy food. With their combined expertise and resources, Nuvance and Bejo have an excellent team in place to respond to these developments. By supplying the highest quality seed of varieties well adapted to local growing conditions, by working with growers, sharing agricultural knowledge and, improving logistics, both companies are confident they can contribute significantly to vegetable production. Bejo and Nuvance are committed to ensuring the sustainable success of the growers, who in turn play a vital role in reaching the goal of African food security.

‘Proudly in Africa for Africa.’

Floris Kotze, commercial manager of Nuvance, says: “We take pride in joining forces with Bejo, enabling us to focus on the professional vegetable market and bring our service offering in line with the high ambitions set out in 2018. Nuvance will benefit from Bejo’s advanced technology and expertise, bringing substantial improvement to our business operations.

For our customers, this means even better support through enhanced customer services, product innovation and tailormade cultivation advice.”

John-Pieter Schipper, CEO of Bejo, says: “We welcome our new colleagues from Nuvance to the Bejo family and look forward to deepening our existing relationship. Their extensive experience and knowledge of the South African market gives me great confidence that we can realize our joint ambitions. We know from other markets that local expertise and dedication are vital to operating successfully. Innovation in professional vegetable production is needed to keep up with the increasing demand for healthy, delicious vegetables throughout Southern Africa. This is an important milestone for both our companies.”

During the coming months, Nuvance will be fully integrated into the Bejo organization. With focus on the high-end professional market, this implies that some changes in the

current assortment may be expected. These will be thoroughly evaluated and discussed with customers and suppliers involved. In the interim, Nuvance will do business under the current name, whilst customers and partners will see no change in their relationships with their trusted contacts. Despite some anticipated changes in the management, Bejo intends to continue working with the entire team of Nuvance specialists.

Bejo and Nuvance would like to use this opportunity to thank Klein Karoo Seed Marketing for the successful partnership in the past, as both companies continually aim to go ‘beyond vegetable seed’.

About Nuvance Nuvance strives to be an innovative and reliable supplier of high-quality seed, advice and professional services within the vegetable seed value chain across Sub-Saharan Africa.

Working with expertise and passion, Nuvance continually aims to make a significant difference in complimenting producers’ businesses to ensure sustainability. This is achieved by supplying our customers with the best genetics, which benefits their businesses though minimizing risk whilst optimizing yield and quality.

About Bejo Bejo is an internationally leading company specialized in the breeding, production, processing and sales of quality vegetable seeds. With an assortment of some 50 crops and more than 1,200 varieties, Bejo offers a complete programme for all markets and a wide range of climates. The Dutch family company has expanded over the years in an organic, ongoing process, shaped by interaction between growers, dealers, supply chain partners and its own employees. All partners have the freedom, within their own local market, to get the most out of Bejo’s products. With operations in more than 30 countries and over 1,800 employees, we are dedicated to offering the best service and developing the best vegetable varieties for the present and the future - Exploring nature never stops.

Note to the editor For additional information, contact: Nuvance: tel. +27 (0)10 534 8147, info@nuvance.co.za Bejo: tel. +31 (0)226 396162, media@bejo.nl

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news

B

ejo en Zaad Holdings kondig met graagte Bejo se oorname van Nuvance vanaf 1 Julie 2020 aan. Nuvance was ‘n dogtermaatskappy van Klein Karoo Saad Bemarking en deel van Zaad Holdings.

Bejo is ‘n Nederlandse familie-onderneming wat spesialiseer in die internasionale groentesaad-bedryf met die teel, produksie en verkope van groentesaad. Nuvance is ‘n gevestigde SuidAfrikaanse saadverskaffer met omvattende kundigheid in suidelikke Afrika, 'trots in Afrika vir Afrika'. Beide maatskappye werk al vir jare saam aan die ontwikkeling van die SuidAfrikaanse groentesaad-bedryf en deel ‘n toegewydheid teenoor die professionele groentemark.

Onlangse sosio-ekonomiese veranderinge regoor Afrika dryf ‘n groeiende vraag na hoë gehalte, gesonde voedsel wat plaaslik geproduseer kan word. Met gekombineerde kundigheid en hulpbronne by Nuvance en Bejo is daar 'n uitstekende span in plek om hierdie te laat realiseer. Deur saad van die hoogste gehalte te voorsien wat goed aangepas is vir ons plaaslike groeitoestande, deur direk met produsente te werk, landboukennis te deel en logistiek te verbeter, is beide maatskappye vol vertroue dat ons belangrike bydrae tot groenteproduksie kan maak. Bejo en Nuvance is verbind tot die volhoubaarheid van ons kliënte, wat 'n belangrike rol speel om die doelwit van voedselsekerheid in Afrika na te streef.

‘Trots in Afrika vir Afrika.’

Floris Kotze, kommersiële bestuurder van Nuvance, sê: “Ons is trots daarop om deel van Bejo te wees. Dit stel ons in staat om op die professionele groentemark te fokus en sodoende die hoë ambisies wat in 2018 uiteengesit is te bereik. Nuvance sal baat by Bejo se gevorderde tegnologie en kundigheid, wat ons bedryfsaktiwiteite aansienlik sal verbeter. Vir ons kliënte beteken dit nog beter ondersteuning deur kliëntediens, innovering van produkte en persoonlike verbouingsadvies.”

John-Pieter Schipper, uitvoerende hoof van Bejo, sê: “Ons verwelkom ons nuwe kollegas van Nuvance tot die Bejofamilie en sien daarna uit om ons bestaande verhouding te versterk. Nuvance se uitgebreide ervaring en kennis van die Suid-Afrikaanse mark gee my die groot vertroue dat ons ons gesamentlike ambisies kan verwesenlik. Vannuit ander markte het ons geleer dat plaaslike kundigheid en toewyding

noodsaaklik is om suksesvol te kan funksioneer. Innovasie in professionele groenteproduksie is nodig om tred te hou met die toenemende vraag na gesonde, smaaklike groente in die hele Suider-Afrika. Hierdie is 'n belangrike mylpaal vir albei ondernemings.”

Gedurende die komende maande sal Nuvance volledig in die Bejo-organisasie geïntegreer word. Met die fokus op die professionele groentemark, impliseer dit dat daar 'n paar veranderinge in die huidige produkreeks verwag kan word.

Hierdie word deeglik geëvalueer en bespreek met die betrokke kliënte en verskaffers. Intussen tyd sal Nuvance onder die huidige naam besigheid doen, terwyl kliënte en vennote steeds die verhoudings met hul bestaande kontakte by Nuvance kan voortsit. Afgesien van 'n paar veranderings in die bestuur, beoog Bejo om met die hele span Nuvance-spesialiste saam te werk.

Bejo en Nuvance wil ook net van hierdie geleentheid gebruik maak om Klein Karoo Saad Bemarking te bedank vir die suksesvolle vennootskap in die verlede, aangesien beide maatskappye voortdurend daarna streef om 'meer as net groentesaad' te bied.

Oor Nuvance Nuvance streef daarna om 'n innoverende en betroubare verskaffer te wees van groentesaad, advies en professionele dienste regoor Suider-Afrika. Met kundigheid en passie probeer Nuvance voortdurend om die volhoubaarheid van groenteprodusente te verseker. Dit word bereik deur ons kliënte die beste genetika te bied om sodoende risiko te beperk, terwyl hul boerderye voordeel trek uit hoë opbrengste en goeie kwaliteit produk.

Oor Bejo Bejo is 'n toonaangewende internasionale saad­maatskappy wat spesialiseer in die teel, produksie, verwerking en verkoop van gehalte groentesaad. Met 'n verskeidenheid van ongeveer 50 gewasse en meer as 1200 variëteite, bied Bejo 'n volledige produkreeks vir ‘n wye reeks markte en klimaatstoestande. Die Nederlandse familie-onderneming het oor die jare uitgebrei en is gevorm deur interaksie tussen telers, handelaars, vennootskappe in die verskaffingsketting, asook sy eie werknemers. Alle vennote het die vryheid om binne hul eie plaaslike mark die beste uit Bejo se produkte te put. Met bedrywighede in meer as 30 lande en 1 800 werknemers wêreldwyd is ons daartoe verbind om voortdurend die beste diens en groentevariëteite te lewer.

Nota aan die redakteur Vir meer inligting, kontak: Nuvance: tel. +27 (010) 534-8147, info@nuvance.co.za Bejo: tel. +31 (0)226-396162, media@bejo.nl

brassica stunting disease (BSD) update

B

rassica crops, in particular cabbages, have long been popular with South African consumers and can provide farmers with a sustainable shortterm income, every 90 to 120 days. The downside for brassica growers is trying to keep these crops clear of pests and diseases. The list of diseases that cause problems for brassica growers in South Africa are long and varied in their causes, and in the last six years another newcomer has been added to the list, in the form of the Brassica stunting disease (BSD).

According to the Department of Agriculture, Forestry and Fisheries, diseases that are problematic to brassica growers in South Africa include black rot (Xanthomonas campestris pv. campestris), Alternaria leaf spot (caused by a complex of three Alternaria species) white rust (whiteblister) (Albugo candida), downy mildew (Peronospora parasitica), black leg (Phoma lingam), club-root (Plasmodiophora brassicae), bacterial leaf spot (Pseudomonas syringae pv. maculicola) and Fusarium wilt (Fusarium A

C

B

oxysporum). The newest addition to this list is the Brassica stunting disease that first appeared in Brits in the North West Province in 2012. Since then the disease has been reported in all the Provinces in South Africa, except the Western Cape. Disease pressure for the above mentioned list of brassica pathogens vary across the different Provinces, but industry representatives are in agreement that BSD, along with whiteblister, clubroot and black rot, are one of the four most important diseases affecting brassica production in South Africa.

The BSD affects various Brassica species, but cabbages (Brassica oleracea var. capitata) appear to be the most affected crop. The disease is characterized by stunted plants, flattening and sometimes purpling of the leaves, side shoot development, vascular discoloration in the stem and/or midrib of leaves and poor root development (fig. 1). Over the last six years, researchers at the University of Johannesburg have investigated the BSD and have shown that the disease E

D

Figure 1: Disease symptoms of cabbage plants affected by BSD. A: Severe Stunting B: Flattening, Purpling C: Poor root development D: No, or small head formation E: Vascular discoloration (phloem)

6

research article by dr lindie esterhuizen

is not seed, soil or water borne, but are transmitted by various aphid species, including Myzus persicae (peach-potato or green-peach aphid). Because there are no crop cultivars resistant to BSD yet, the study has turned its focus towards disease management strategies and have investigated the use of chemical control of the aphid vector. Findings of this research project were recently shared directly with growers during four BSD information days held during the month of July, 2019.

The four BSD information days were held in different brassica production regions of South Africa, which were Lydenburg (Mpumalanga), Bloemfontein (Free state), Hilton (KwaZuluNatal) and Marble hall (Limpopo).

These events were organized and funded by Sakata, Starke Ayres, Syngenta, Bayer, the Seedling Growers Association of South Africa (SGASA) and McCain Foods.

The four events were attended by both growers and different role players from the industry, including representatives from nurseries, agricultural chemical companies and seed companies.

All the information days were well supported, with between 34 and 43 people attending the first three days. The last information day held in Kwazulu-Natal was particularly well supported, with 88 farmers and industry representatives attending the lecture at the Cedara College of Agriculture.

In many areas in South Africa, Brassica production by commercial or smallholder farmers occur throughout the year, but depending on the local climate and irrigation conditions, some areas practice only summer or winter cropping.

The BSD has been reported to affect cabbage production in all seasons, depending on the area of production. In Brits (North West), where the disease was first noted, it is particularly a problem during the winter months and crops planted after February are affected every year. Disease monitoring in that area over the last 5 years have recorded disease pressures ranging from 50% to 95% in successive years. No formal BSD monitoring has occurred in other areas in S.A., but according to farmers attending these four events, BSD only really started to become problematic in their areas after 2014, with some areas only becoming aware of the disease in the last three years (2017- 2019). Most of the growers in these areas also reported much lower and inconsistent disease pressures (compared to the trend seen in Brits) for 2018 and 2019, i.e. 10-80% in KwazuluNatal, 10-50% in Limpopo, 3-10% in Mpumalanga and 10-40% in the Free State. Very worryingly, a number of farmers that have experienced successive seasons with 70 – 90% disease incidence have indicated that they are pulling out of the cabbage market due to the high crop and financial losses.

From net house experiments carried out in Brits between 2014 and 2016, it was clear that the BSD is transmitted by a flying insect vector. In 2015, an insect transmission experiment was carried out to identify this vector. Collection of the predominant insect species occurring in BSD affected cabbage fields in Brits and caging of these insects (i.e. aphids, plant and leaf hoppers and whiteflies) on cabbage seedlings resulted in the identification of aphids as the BSD insect vector. Only cabbage seedling cages with the aphid species Myzus persicae, developed typical BSD symptoms after 45 days. Consequently, an aphid monitoring study was carried out in Brits between 2016 and 2018, which identified a total of 36 different aphid species feeding on brassica crops. The four predominant species were M. persicae, various Aphis spp., Rhopalosiphum maidis (corn aphid) and R. padi (Bird cherry-oat aphid). At the moment all these aphid species are considered potential BSD vectors.

Aphids are small sap-sucking insects. There are about 4,700 different species that vary greatly in their morphology (appearance) and life cycle characteristics. Around 400 aphid species are considered agricultural pests of food and fibre crops, and about 250 species have been reported in South Africa. They are considered destructive pests because they weaken plants by sap depletion and most importantly, both nymphs and adults act as vectors for over 100 plant viruses. Aphids have a fairly complex life cycle, including both a summer (herbaceous) and winter (woody) host, a sexual and asexual reproduction phase, as well as the production of both a wingless and winged adult form at certain times of the year (fig. 2 and fig. 3). The wingless form is known to colonize summer crops and are responsible for secondary spreading of plant viruses within a field, whereas the winged form do not colonize plants, but are passively carried by wind over long distances and are responsible for primary infection in field crops. It is in particular the presence of the two different aphid types, i.e. winged vs wingless, that are an important factor influencing the success of control strategies targeting aphid transmitted diseases, like the BSD. Probably the most important and eagerly awaited information shared with the growers at the BSD information days, was the research results regarding chemical control of the BSD. The effectiveness of several commercially available systemic insecticides to reduce aphid infestation and BSD infection were

Figure 2: Three morphological developmental stages of M. persicae. A: nymphs and the wingless apterae and B: the winged alate adult. (https://cabiplantwise.files.wordpress. com/2017/02/geren-peach-aphid.jpg) investigated during 2017 and 2018. To reduce the cost impact on crop production, the evaluated insecticides were used in the form of two seed treatments (Sanokote (Dummypil), (thiamethoxam); Cruiser (thiamethoxam)) and three seedling drenches (Actara (thiamethoxam); Kohinor and Confidor (imidacloprid)). For the field trial, a susceptible cabbage cultivar was used and after treatment, it was transplanted into the open field in Brits, along with untreated plants as control.

Aphid activity/infestation within the field was monitored weekly, by trapping winged aphids in yellow bucket traps and direct counting of winged and wingless aphids on the treated and untreated cabbage plants. The results for the two years are summarised in fig 4. In 2017, symptoms of the BSD appeared early in the season and were quite severe (fig. 4A). The numbers of winged aphid counted in the traps and on the plants were relatively low throughout the season (5%), but the colonizing, wingless aphids (75%) appeared soon after transplant and increased steadily in numbers over the season (8018 total aphid count) (fig. 4E, F). Under these conditions, the use of systemic insecticides was highly effective in reducing aphid colonization and BSD in the treated cabbage

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research SUMMER summer hosts

Reproduction typically does not involve males (parthenogenesis) and results inlive birth, where the embryos develop within the mother, which then give birth to live nymphs.

Winged females maydevelop later in the season, allowing the insects to colonise new plants.

wingless adult spring migrant

SPRING

summer migrant

fall migrant

sexual forms on peach

MYZUS PERSICAE stem LIFE CYCLE mother Overwintering eggs hatch in Spring, resulting in flightless females, called stem mothers.

eggs on peach

FALL Alternation between 2 host plant species (Annual crop and woody plant).

A phase of sexual reproduction occurs in the Autumn, with the insects often overwintering as eggs.

WINTER Figure 3: A representation of the life cycle of Myzus persicae, the green-peach aphid. The life cycle including both a summer (herbaceous) host that include plants from over 40 families (i.e. vegetable crops in the families Solanaceae, Chenopodiaceae, Compositae, Brassicaceae, and Cucurbitaceae) and a winter (woody) host, particularly Prunus spp., especially peach, apricot and plum trees. Reproduction occur both by a sexual and asexual reproduction phase in these two different seasons, and the production of both a wingless and winged adult form occur at certain times of the year.

(Figure adapted from Radcliff, Ragsdale and Flanders, Management of aphids and leafhoppers, St Pileups Press, 1993). plants, with Actara (8%) and Kohinor (9.2%) significantly reducing BSD incidence in comparison to the untreated control (54%) (fig 4G). In 2018, the number of winged aphids (62%) were much higher throughout the season (fig 4E, F), but there were much less colonizing wingless aphids (37%) (2445 total aphid count).

In this year, the symptoms of BSD appeared much later in the season (fig 4B) and disease severity was much lower, probably due to the later occurrence of infection in 2018. As a result, the systemic insecticides were much less effective in controlling both the number of migrating wingless aphids counted on the crop plants and the BSD incidences (53% - 69%) (fig. 4G).

At first, the presentation of such contrasting results regarding chemical control of BSD were highly disappointing to both the growers and industry representatives. However, the results are indeed a reflection of the complex nature of the BSD pathosystem. BSD is transmitted by aphids as its insect vector; consequently any fluctuation in the aphid populations (i.e. aphid numbers, species or morphological types) will result in varied disease pressure. Indeed, disease monitoring in Brits over the last 5 years has revealed a bi-annual pattern in BSD incidence, with disease incidences of approximately 90% and 50% every second year (Table 1). This fluctuation in BSD incidence seemed to correlate with the fluctuation in total aphid numbers, as monitored between 2016 – 2018, i.e. higher aphid numbers result in higher disease pressure.

The results have also suggested that the interaction between the insect vector and BSD incidence is more complex, because it is not only dependant on the aphid numbers in a season, but also the aphid types (winged vs wingless) and the timing of their appearance that play a role in disease incidence. Firstly, late season flights of winged aphids into the field will render insecticide application at the seed or seedling stage ineffective. Secondly, in seasons with high numbers of winged aphids throughout the season, additional follow-up treatments in the field will be required to extend the period of protection. Limiting the spread of BSD between fields (the migration of winged aphids from one field to nearby fields to inoculate a new field), is far more difficult, probably due to the inability of insecticides to instantly kill disease carrying aphids and thereby prevent infection. Research on Potato leaf roll virus (PLRV) transmission by M. persicae in potatoes has shown that even when the insecticide residues are still present within plants, virus-carryingwinged aphids are not killed quickly enough to prevent virus transmission (by the time the aphid ingests the toxic active substance of the insecticide from the phloem sap, they have already transmitted the virus and only die after transmission). Hence, special precautions must be taken against winged aphids when attempting to control the BSD. Figure 4. (A) In 2017, BSD associated symptoms such as stunting,

yellowing and flattening of the leaves were observed as early as week 6 after transplanting. Most of the infected plants displayed a patch effect, i.e. adjacent plants within the same block exhibiting symptoms. (B) In comparison, at week 10 after transplant in 2018, the cabbage plants still appeared healthy, and the patch effect was not observed. (C) Total number of winged, wingless and parasitized aphids were counted directly on the cabbage plants. In 2017, a total of 8018 aphids were counted and in 2018 (D), a total of 2445 aphid were counted. The total (E) winged aphid and (F) wingless aphid counts per week for 2017 (12-weeks) and 2018 (14-weeks) counted on a weekly basis, are indicated. (G) The BSD incidence (%) in treated and untreated cabbage plants in 2017 and 2018 are compared.

In light of the current information available on the BSD, the following advice are given to brassica growers attempting to control BSD infection. At a minimum, a seed or seedling treatment should be included in the nursery to prevent infection within the first 6 weeks. Our research has shown that the disease is not seed transmissible and that infection occur shortly after transplant into the field, as aphids start to feed and colonize the crop within the first day. It is also very important that the seedling treatment are administered at least one day before transplant into the field (not as a seedling drench in trays adjacent to the field, on the day of transplant), to give the plant time to absorb and transport the systemic insecticide throughout the plant, before aphid exposure occur in the field. Next, to extend the period of protection within the field, growers should speak to their pest control representative about an insecticide program to control aphids throughout the season, particularly in seasons with high aphid numbers or high numbers of winged aphids. In seasons with high aphid numbers, particularly winged aphids, growers should attempt to reduce aphid numbers within the larger farming community (group effort), as aphids are transported over large distances by wind and this will make chemical control of BSD highly problematic. Farmers are advised to go through their lands regularly and remove all plants showing BSD symptoms to reduce the amount of infected material. It might also be

2014

2015

2016

2017

2018

BSD infection incidence

92%

52%

95%

54%

65 - 69%

Total number of aphids counted

17kg

4153

2255

8590

Table 1: A summary of BSD incidences and aphid activity monitored in Brits over a 5-year period.

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research 2018

B

A

A

Cabbage plants exhibiting BSD symptoms at 6 weeks

Cabbage plants exhibiting BSD symptoms at 10 weeks

C

D

C

5% Winged Wingless Parasitized

1%

Winged Wingless Parasitized

37%

20% 75%

62%

2017: 8018 aphids

2018: 2445 aphids

E

F

2017 2018

E

2017 2018

TOTAL APHID COUNTS

a good idea to remove or apply herbicide to any weedy areas around the land. It is highly likely that wild brassica species growing as weeds around the crop are a symptomless reservoir for the BSD. The research results have also highlighted the importance of aphid monitoring during the growth season, especially aphid flight activities. The use of aphid monitoring data, in the form of yellow bucket traps by growers themselves, or suction trap data to forecast aphid activity and flight patterns (recorded by the South African aphid monitoring system and currently used predominantly by potato and wheat growers), should be implemented to provide an early warning system about the risk for BSD infection in a specific area or season.

2017

TOTAL APHID COUNTS

Figure 4. (A) In 2017, BSD associated symptoms such as stunting, yellowing and flattening of the leaves were observed as early as week 6 after transplanting. Most of the infected plants displayed a patch effect, i.e. adjacent plants within the same block exhibiting symptoms. (B) In comparison, at week 10 after transplant in 2018, the cabbage plants still appeared healthy, and the patch effect was not observed. (C) Total number of winged, wingless and parasitized aphids were counted directly on the cabbage plants. In 2017, a total of 8018 aphids were counted and in 2018 (D), a total of 2445 aphid were counted. The total (E) winged aphid and (F) wingless aphid counts per week for 2017 (12-weeks) and 2018 (14-weeks) counted on a weekly basis, are indicated.

(G) The BSD incidence (%) in treated and untreated cabbage plants in 2017 and 2018 are compared.

WEEK NUMBER

WEEK NUMBER

Winged aphids

G

Wingless aphids

G

80 70 60

2017 2018

50 40 30 20 10

*

*

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TREATMENT

BSD infection %

2

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bacterial canker and wilt in fresh market tomatoes wilting of the plant. Wilting starts on the lower leaves and progresses upward in the canopy, sometimes showing wilting on one side of the plant.1,2

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• •

Bacterial canker and bacterial wilt result from the systemic infection of the vascular system of tomato plants.

Disruption of the vascular system leads to wilt and possibly plant death.

Management efforts should focus on integrated strategies to prevent infection.

Young plants can wilt rapidly and eventually die while older plants usually wilt but remain alive. When leaflets wilt, the petioles stay attached and turgid. A light brown discoloration of the vascular tissue develops, most prominently at the nodes and just above the soil line. With time this discoloration becomes a dark reddish-brown (Figure 1). Light streaks may be visible externally on the stems, and these can darken and become cankers as the plant ages. Bird’s-eye spots (Figure 2) develop on the fruit. These spots are 3 to 6 mm in diameter with brown centers surrounded by creamy-white halos.1,2

B

acterial canker (caused by Clavibacter michiganensis subsp. michiganensis) is one of the most destructive bacterial diseases of tomato. Both primary (systemic) and secondary (foliar) infections result in significant reductions in yield and fruit quality. Primary infections start from infected seed or young seedlings. The pathogen enters the vascular tissue, which results in systemic

Figure 2: Bird’s-eye spots on tomato fruit infected with bacterial canker. Mary Ann Hansen, Virginia Polytechnic Institute and State University.

Bugwood.org.

Figure 1: Internal discoloration of stem tissue from systemic bacterial canker infection. Gerald Holms, California Polytechnic State University at San Luis Obispo. Bugwood.org.

Spread of the pathogen from plant to plant in the field results in foliar infections, which result in leaves becoming chlorotic with brown-black margins. This secondary spread can also cause the bird’s-eye fruit spotting, but no wilting or vascular discoloration will occur.2 The greatest yield losses result from the primary infection of seedlings. Secondary (foliar) infection may not result in substantial reductions in yield or quality.

12

research The bacterial canker pathogen overwinters on and in contaminated seed, in infested plant debris, and on volunteer tomatoes and weed hosts. Depending on conditions, the bacterium can survive for 1 to 2 years on crop debris. The bacterium can also survive on contaminated wooden stakes, seedling flats, and greenhouse benches used for transplant production. The pathogen is spread by splashing water and on contaminated tools.1 The bacterium infects the plant through natural openings, root wounds, and pruning wounds.2

Sanitation is important during transplant production. All plant material should be removed from the greenhouse before starting a new crop of seedlings. Weeds and volunteers in and around the greenhouse should be eliminated.

Growth media should be sterilized, and previously used flats, pots, racks, and stakes should be disinfested. Tools and greenhouse surfaces should be cleaned and treated with a disinfectant. Avoid contact between seedlings from different seed lots, and minimize the handling of seedlings. Choose irrigation methods and schedules The strategies used for managing to minimize the hours of leaf bacterial canker are similar to those wetness. Do not handle wet plants, used to manage bacterial spot and and allow plants to dry before speck. The most critical strategy is transporting them to the field. the use of disease-free seed and Remove and destroy symptomatic transplants. With bacterial canker, seedling and any seedling trays one infected seed in 10,000 is immediately adjacent to the trays enough to initiate an epidemic. containing infected plants.1,2 Seed should be disinfested with hot water, rather than with chlorine In the field, eliminate sola­naceous or acid treatments because the weeds and volun­ teer tomato pathogen can be present under plants. Plow under crop debris the seed coat where chlorine shortly after the last harvest. Rotate and acid cannot reach. The seed fields to non-solanaceous crops. should be tested for the presence For canker, a 3- to 4-year rotation of the bacterium after treatment. away from solanaceous crops is If purchasing treated seed from recommended. Promote good a supplier, growers should ask water drainage, and, if possible, what treatments were used, what plant seedlings from different procedures were used to ensure seed lots in different locations. that all seed were adequately Whenever possible, keep workers treated, if disinfesting solutions out of the fields when foliage is were monitored and how often, and wet, and avoid pruning plants if treated seed lots were tested for when leaves are wet. Avoid the use the presence of the pathogen.2 of overhead irrigation if possible; if

not, use low-pressure systems that minimize the spread of bacteria through splashing. Carefully rogueout and destroy symptomatic plants. Clean equipment and tools between plantings.1,2,3 Bacterial wilt (caused by Ralstonia solanacearum) is a devastating disease of tomatoes in the warm, subtropical regions where it occurs. The disease initially appears as a wilting of the youngest leaves, quickly followed by a complete wilt of the entire plant (Figure 3). If the development of wilt progresses slowly enough, adventitious roots can form on the stems.

Figure 3: Symptoms of bacterial wilt on tomato.

Don Ferrin, Louisiana State University. Bugwood.org.

Bacterial wilt is favored by warm temperatures. The wilt pathogen has a very broad host range, infecting several hundred plant species in over 50 different plant families.

The bacterium can also survive in the soil for extended periods in the absence of a susceptible host, obtaining nutrients from the root systems of non-host plants.

High pH and calcareous soils are not favorable for the survival of this pathogen.1 The pathogen is introduced to a field in infested soil, in contaminated irrigation water, or on infected transplants. Seed transmission is not considered to be important for this disease. The pathogen infects plants through root wounds. After infection, the bacterium enters the xylem (water conducting tissue) where the bacterium multiplies and clogs the xylem elements, slowing the movement of water in the plant, resulting in wilting. Disease development is favored by high temperatures and high soil moisture levels.1 Bacterial wilt is difficult to manage once the pathogen becomes established in a field. No single management strategy will provide adequate levels of control. The primary focus should be on preventing the introduction of the pathogen in infested soil, contaminated irrigation water, and infected transplants. Field tools and equipment should be thoroughly washed before moving from a contaminated field to a disease-free one. Contaminated pond water should be treated with chlorine to eliminate the pathogen. Some wiltresistant varieties of tomato are available, but these can quickly become ineffective when new strains of the pathogen are present. Crop rotation to nonhost crops, especially grasses such as sorghumsudangrass can help lower pathogen populations, as will liming the soil to increase the soil pH. Avoid over irrigating the crop.1

Sources 1 Jones, J., Zitter, T., Momol, T., and Miller, S. 2014. Compendium of tomato diseases and pests, second edition. American Phytopathological Society, St. Paul, MN. 2 LeBoeuf, J., Cuppels, D., Dick, J., Loewen, S., and Celetti, M. 2005. Bacterial diseases of tomato: bacterial spot, bacterial speck, bacterial canker. OMAFRA FactSheet, ISSN 1198-712X. 3 Saha, S., Pfeufer, E., Bessin, R., Wright, S., and Strang, J. 2016.

Vegetable production guide for commercial growers, 2016-17.

University of Kentucky, Cooperative Extension Service. ID-36.

Additional information For additional agronomic information, please contact your local seed representative. Developed in partnership with Technology Development & Agronomy by Monsanto.

Individual results may vary, and performance may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. The recommendations in this article are based upon information obtained from the cited sources and should be used as a quick reference for information about bacterial diseases of tomato. The content of this article should not be substituted for the professional opinion of a producer, grower, agronomist, pathologist and similar professional dealing with this specific crop.

SEMINIS DOES NOT WARRANT THE ACCURACY OF ANY INFORMATION OR TECHNICAL ADVICE PROVIDED HEREIN AND DISCLAIMS ALL LIABILITY FOR ANY CLAIM INVOLVING SUCH INFORMATION OR ADVICE.

14

advancing beyond the basics seeds | science | service

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SV 7846 TH •

•

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Suitable for undercover production Good tolerance of TYLCV and Powdery Mildew Suited for year round production

SV 6112 TH* • •

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Indeterminate tomato Suitable for open field and undercover production Excellent maturity and fruit quality Good disease package

SV 4129 TH* •

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Well suited for undercover and open-field production Vigorous plant growth and a high fruit set Good fruit size with very good quality

impressions of the northern cape onion industry

I

n November 2019, I came from a cold and wet Holland to the hot and dry Northern Cape in South Africa. The advice was to bring shorts, a hat and sunblock. From Johannesburg, we took a short internal flight to Kimberley and visited the surrounding areas to see onion growers and evaluate our field breeding trials. For me, the most remarkable thing was that the majority of the harvesting is done by hand in this part of the world with only some growers making use of mechanical harvesting. After harvesting, many growers still store their onion on the field, while others have changed over to more professional storage facilities in big sheds, wooden boxes or even left loose and with forced air ventilation. Some growers also combine these two storage methods by leaving the onions on the field for a short period before then placing them into boxes or bins. My first question was how do they prevent sunburn and stimulate air movement through the onions while they are still on the field?

Harvesting takes place while the onion foliage is still green and the onions are fresh. Never have I seen so many people in a single field picking up onions and putting them on a pallet. Onions are then layered in a circle (bulbs towards the center) to form an "iglooshaped" hump making sure to leave a chimney-like opening the middle for air to get through. The outer leaves protect the onions from getting sunburnt, while a piece of wood or carton is placed on top the protect the onions from rain. The onions can be stored in the field like this for 3 or 4 months!. This surprised me because in the Netherlands onions should be off the field within one week after harvesting. The relative humidity in the Netherlands is much higher, making it difficult to dry and store onions on the field for such an extended period.

At De Groot en Slot we are continually trying to increase the genetic potential of our onions, especially with regards to yield, colour, storability

(outside and/or inside), firmness, skin and also the onion in general. Can you always trust such an onion variety? Will it germinate quickly and uniformly and are there different stages of germination? What is the nitrogen requirement of this specific variety? These and others are the attributes we consider in a variety when we are evaluating them in our breeding trials. In these trials, we have seen some very promising new varieties but also some that are prone to bolting for instance. At altitudes above 1000 meters bolting is a possibility, as a result, we are continually looking for varieties with good bolting tolerance especially for the Northern Cape. During one of our field visits, we witnessed an instance where a competitor variety had several bolters whilst one of our new varieties namely Itaparica*, planted in the same field did not. Itaparica* not only performs well in South-Africa but also in Brasil, Argentina and other countries throughout Middle and South America.

16

industry article by jaap jonker

We ended the visit to the Northern Cape with an onion field day. Many of the onion growers as well as leading seed suppliers attended this event. In the Netherlands, we also host and attend open days. The challenge is however, to ensure that your variety stands out and that the audience still remembers all the unique selling points which you mentioned. Not always an easy task when you have so many leading onion seed companies with good varieties.

Floris Kotze, came up which a brilliant solution for this. He always had some Itaparica* in the bakkie to be able to show it to growers whilst mentioning its qualities and making sure the unique name, Itaparica* stuck. After that day everybody knew of Itaparica*!

As De Groot en Slot we always try to do things slightly different to others, so on our open days we like to show a short video clip of the variety which we are promoting on that day.

In this video clip, the story is being told from the seed's perspective, where it's telling the story of how he/she was made, which parents he/she has, how he/she was produced, how he/she was harvested, how he/she was tested, how many brothers and sisters he/she lost because they were not good

enough, how he/she was treated, how he/she was packed and how he/she was delivered to the grower and sown. After a period on the field, the onion became an adult and was probably shipped to South Africa!

It is great to see that we share this innovative spirit with Nuvance as they are also trying to do things differently. Do the right things with the right genetics at the right time together with the right people!

In closing, I want to thank all the growers who were willing to openly share their onion cultivation methods and the warm hospitality which I experienced during my visit to South Africa. I have been to South Africa 4 times last year and I really like this country, so much so that I am planning to bring my family for a vacation. You can be proud of the possibilities here and I will rather not focus too much on some other things what could be improved. Don't waste your energy on things that you are unable to change, rather focus on that which you can.

Baie dankie!!

Jaap Jonker, Sales manager at De Groot en Slot

18

oplossings gedryf deur advies saad | wetenskap | diens

Buzios*

Maragogi* • • •

Vroeë kortdag-ui Ferm met klein wortelaanhegting Geskik vir die varsmark

• • • •

| www.nuvance.co.za |

Medium kortdag-ui Goed aangepas vir produksies in die Noord-Kaap Ideaal vir die varsmark Medium-vroeg kultivar

Makalu • • • •

Vroeë intermediêre dag-ui Geskik vir die varsmark Medium tot dun nekgrootte Uitstekende opbrengspotensiaal

bees and bejo: natural partners in seed production

B

ejo is an international producer of vegetable seeds. Honeybees are perhaps our most important employees. We keep our own bees and are internationally active in bee breeding and research. Alongside better vegetable varieties, we also work to improve bee colonies.

Bees play an important role in the fertilization of plants, including food crops. For a plant to bear fruit or form seeds, the (male) pollen must first make its way to the (female) pistil of the flower. Some types of plants, such as red beet and spinach, are pollinated by the wind. Others, such as lettuce, are self-pollinating.

But many of the plants that are essential for our food supply rely on insects for pollination.

Honeybees: Pollination champions Nature provides plenty of pollinators, including bumblebees and solitary wild bees. But honeybees are pollination champions. They can be so effective because they can be used purposefully and in large numbers. Each hive that a beekeeper places in a field contains a colony of some 20,000 to 40,000 pollinators. Not surprisingly, fruit growers and growers of some fruit vegetables and open field crops work closely with professional beekeepers.

Bejo’s core business makes us uniquely aware of the importance of bees: without pollination, there would be no seeds. We grow seeds in greenhouses and on fields all over the world, so we have tens of thousands of honeybee colonies working for us. “At Bejo we have our own beekeepers and are active in bee research. That way we can gain more experience with beekeeping and a greater understanding of bees and pollination,” says Youri Draaijer, Coordinator of international seed production research at Bejo. “With our research we hope to find out more about the typical characteristics of bee colonies and bee types, including foraging zeal, or the willingness to collect nectar, and tendency to swarm, or leave the hive. But the main focus of our research is bee health.”

20

industry Research and selection to improve bee health Worldwide, there is an urgent need for more expertise and new developments in this area. This is partly because healthy bees are the best pollinators, and partly because in the past century bee populations have been declining due to bee mortality. The decline in numbers has various causes. One of the biggest problems for the western honeybee is the varroa mite, a parasite that infests hives and weakens or kills bees.

Bees can also die of exhaustion in colonies that work too hard, a situation known as winter loss. Pesticides are also mentioned as a possible cause of population decline.

Feeding and selection In our research we look for ways to use food and better beekeeping techniques to develop stronger bee colonies. We are also making progress in selecting bees with the desired characteristics to start new colonies. Our core activity is the selection and breeding of plants in order to achieve better varieties. We have the same goal with bees. We breed bee colonies and seek to develop types that perform well and thrive.

Unique position in international beekeeping community A large part of our research is concentrated at Bejo France, which works closely with the apiaries of Bejo in the Netherlands. In addition there are programs operating in other countries where we grow our seeds.

In New Zealand Bejo works with Midlands, a large seed production specialist and an important Bejo partner.

For seed production alone, Midlands uses some 3,500 active hives. In Australia we are setting up our own apiaries. In this region the limited availability of bees is a challenge. In Australia and New Zealand there is greater competition for bee colonies, because high market prices are paid for certain pure honey types from specific plants and trees, such as manuka and leatherwood. We also have concrete plans to start our own apiaries in the United States, along with a

research program. In the US Bejo currently works only with external professional apiaries.

With its worldwide activities Bejo occupies a unique position in the international beekeeping world. This allows us to create a valuable ‘cross-pollination’ in more than one sense. We work with businesses, universities and research institutions, exchanging knowledge and experience from various parts of the world. Within Bejo, research is coordinated in our own international Bee Group, with former director Ger Beemsterboer as driving force.

Safeguarding pollination, now and in the future For Bejo, investing in apiculture is in the company’s own interest. "We need healthy bee colonies to safeguard natural pollination on our production fields, now and in the future,” says John-Pieter Schipper, CEO of Bejo. On the other hand, he adds, Bejo also invests in bees out of a sense of social commitment.

'The key role that bees play reminds us that food production depends on nature and the environment. That confirms us in the vision that we, as a family business, have of sustainability' John-Pieter Schipper Bejo values a healthy environment and sustainable use of natural resources. With that in mind, we work to discover the best ways to use natural pollination and to improve the health of our bees.

origins and primary regions of diversity of agricultural crops

alfalfa

beans

clover

eggplants

hops

almonds

blueberries

cocoa beans

faba beans

kiwi

apples

cabbages

coconuts

figs

leeks

apricots

carrots

garlic

lemons & limes

artichokes

cassava

cottonseed oil

ginger

lentils

asparagus

cherries

cowpeas

grapefruit

lettuce

avocados

chickpeas

cranberries

grapes

maize

bananas & plantains

chillies & peppers

cucumbers

groundnut

mangoes

barley

cinnamon

dates

hazelnuts

mate

22 Khoury CK, Achicanoy HA, Bjorkman AD, Navarro-Racines C, Guarino L, Flores-Palacios X, Engels JMM, Wiersema JH, Dempewolf H, Sotelo S, Ramírez-Villegas J, Castañeda-Álvarez NP, Fowler C, Jarvis A, Rieseberg LH, and Struik PC (2016).

Origins of food crops connect countries worldwide. Proc. R. Soc. B 283: 20160792. DOI: 10.1098/rspb.2016.0792. https://blog.ciat.cgiar.org/origin-of-crops/

melons

pears

rice

sunflower

millets

peas

rye

sweet potatoes

oats

pigeonpeas

sesame

taro

olives

pineapples

sorghum

tea

onions

plums

soybean

tomatoes

oranges

potatoes

spinach

vanilla

palm oil

pumpkins

strawberries

watermelons

papayas

quinoa

sugar beet

wheat

peaches & nectarines

rape & mustard seed

sugarcane

yams

hydroponic greenhouse plant populations for tomato production in the eastern cape Plant Population Ten years ago, the benchmark plant population for tomatoes in a closed/ ventilated en­vironment was 3 plants/m² (30 000 plants/ha). Effectively set at a row spacing of 0.85m apart and in-row spacing of 0.33m.

This spacing can still be effective in areas experiencing low humidities during the warmer months. In the coastal regions, it started becoming a problem especially when higher yields were being achieved with improved varieties and vegetative growing conditions. Due to the increased vegetative growth, there was reduced air movement around the plants and in humid coastal conditions, the incidence of fungal diseases such as Botrytis became a large problem wiping out a huge percentage of the increased yield.

As a result, farmers adjusted the plant population down to 2.7 plants/m² (27 000 plants/ha) effectively set at a row spacing of 0.875m apart and in-row spacing of 0.37m.

In a standard 30m x 10m tunnel growers would usually have 10 rows running the length of the tunnel which are fed by 5 dripper lines. So, the dripper lines were set at 1.70m apart feeding 2 lines of plants on either side. It is now common practice to maintain 5 dripper lines but reducing the 10 lines of plants into only 5 lines of plants. So effectively the in-row spacing is reduced to 0.185m, the dripper row spacing remains the same but increases normal row spacing considerably. This practice allows for a larger pathway between the plants, increases the air movement in the structure and reduces the risk of mechanical damage to the plants especially from staff working in the house or from moving spray machinery. It also improves the picking operation from a standpoint of ripe fruit visibility. It furthermore improves the amount of sunlight the plants receive, as close double rows always shadow the inside of the double row above the dripper line particularly after 8 – 10 weeks onwards.

Fertiliser Application Tomatoes are grown in hydroponic environments ideally require an EC of 1.9mS/cm. Anything above this is wasteful and can create toxicity. It is important to have the water source tested before use in a laboratory to establish the mineral content and more importantly the EC of the raw water. Mineral content cannot always be balanced but the overall EC is paramount. For example, if the EC of the raw water is 0.6mS/cm then this is added to the plant EC requirement of 1.9mS/cm giving a total EC requirement of 2.5mS/cm. The grower has to ensure that the inflow of

24

industry article by howard champ

water/fertilizer mix is 2.5mS/cm.

The outflow EC should not exceed more than 0.5mS/cm above the inflow (e.g. 3.0mS/cm would be the maximum). The outflow can be manipulated by the percentage of water run-off daily. For example, 10 – 15% run-off of the total inflow will maintain the outflow EC within the parameters of the inflow EC. If there is a deficit of run-off then the salt residue in the bag will begin to rise and the run-off EC will climb to damaging levels. This can be corrected easily by flushing the bag at night to bring the run-off EC down.

Recommended pH is between 5.8 – 6.0. This window allows maximum uptake of all the nutrients being applied in the fertilizer mix. Natural water is normally around 6.5 – 7.0.

The introduction of acids in the mix will bring the alkalinity down to 5.9. Be sure to adjust the fertilizer programme to accommodate the acid application, as acids can come in the concentrated form of Sulphuric, Phosphoric or Nitric acid at 80%.

Summary 2.7 plants/m² - 27 000 plants/ha (effectively set at a row spacing of 0.875m apart and in-row spacing of – 0.37m.

EC – 1.9mS/cm + Raw water EC = Required EC at inflow. pH – Optimum is 5.6 – 6.0.

estimating vegetable crop water use

A

dequate irrigation design, good irrigation management and scheduling have long been recognized as keys to increasing vegetable production on a sustainable basis. Scheduling irrigation according to crop water needs minimizes the chances of under or over watering.

Consequently, there is less crop failure and leaching of fertilizers beyond the root-zone, and more profit for growers. This approach underpins the long-term viability of an efficient and sustainable production system for the irrigated vegetable industry. Weather data has been used for estimating crop water requirements for many years and is a handy management tool when it is used in conjunction with scheduling methods. Nowadays, it is possible to download a set of climatic data onto a personal computer and use it for estimating crop water use.

The moisture-accounting method The Moisture Accounting Method involves steps to estimate soil moisture content by using weather data. It is based on soil water balance. For instance, if the moisture content of a soil is known at any given time, the moisture content at any later time can be calculated by adding water gains (effective rain and/or irrigation) and subtracting water losses (runoff, deep percolation and crop evapotranspiration - ETc) during the elapsed period.

Keeping the daily water balance is a simple procedure, but it must be completed each day. By knowing the daily values for inflow (rainfall or irrigation) and outflow (crop water use), the daily balance can be calculated as shown in Table 4.

As soon as the accumulated water deficit exceeds the value of the net irrigation application depth (i.e. the net amount of irrigation water applied), more irrigation water is supplied to maintain an optimum soil moisture content for plant growth.

Required data: crop, soil and climate 1. Crop data Crop data: Root depth, growth stages and Crop coefficient.

1.1 Root depth Different irrigation systems influence root development by changing the availability of water at different depths in the soil profile.

A healthy root system is essential for all crops because it facilitates the uptake of water and nutrients.

In some vegetable crops, such as carrots and onions, healthy roots are even more important because roots are the harvested products.

It is important to consider aspects of the root zone at various stages of crop growth. Once you have a good idea of the size of the root system you can modify the irrigation depth and interval between irrigations to suit it. Shallow rooted crops can only extract water from a limited

depth and may require short and frequent irrigations. Deep rooted plants, on the other hand, are able to extract water from deep down but can be prone to root disease if the subsoil becomes saturated.

Rooting depth can be determined by digging out the whole plant, shaking the soil off or digging a soil pit and then measuring the depth of the root system. Table 1 shows the range of typical root depths for various vegetable crops.

Rooting depth and depletion fraction (p), which is the fraction of total available water that can be depleted from the root zone before moisture stress occurs, are vital factors in determining how much water should be applied and when.

1.2 Growth Stages The length of the total growing season and each growth stage of the crop are important when estimating crop water needs. The growth of an annual crop can be divided into four stages: • Initial (establishment): from sowing to 10% ground cover • Crop development: from 10 to 70% ground cover • Mid-season (fruit formation): including flowering and fruit set or yield formation • Late-season: including ripening and harvest.

26

industry Crop

Tomatoes

Onions Green

Dry

Watermelon

Carrot

Lettuce

Broccoli

Cabbage

Root Depth (m)

0.5 - 1.5

0.3 - 0.6

0.3 - 0.6

0.8 - 1.5

05 - 1.0

0.3 - 0.5

0.4 - 0.6

0.5 - 0.8

Depletion fraction (p)1

0.4 - 0.5

0.3 - 0.4

0.3 - 0.4

0.4 - 0.5

0.4 - 0.5

0.3 - 0.4

0.4 - 0.5

0.4 - 0.5

1

The values for depletion (p) apply when ETc ≈ 5 mm/day, otherwise p= p (table 4) + 0.04 (5 - ETc).

Table 1: Root depth and depletion fraction of some selected vegetable crops (Source: Allen et al., 1998).

1.3 Crop coefficient (Kc) A Crop coefficient is a factor for estimating crop water requirements based on reference crop evapotranspiration.

Crop coefficients vary between crops and growth stages, which reflects the changing characteristics of a plant over the growing season. Crop type and growth stages are the major factors influencing the crop coefficient. As the crop grows, the ground cover, crop height and leaf area change. Differences in the crop's evapotranspiration rate over the various growth stages will change the crop coefficient as shown in Table 2.

A crop coefficient relates crop water use at a particular development stage to the amount of evapotranspiration (ET) calculated from weather data.

Crop Coefficient (Kc) X Reference Evapotranspiration (ETo)

Figure 1: Calculating crop evapotranspiration (ETc) (Allen et al., 1998)

Crop

Initial

Development

Mid-season

Late

At harvest

Cabbage

0.41 - 0.52

0.7 - 0.8

0.95 - 1.1

0.9 - 1.0

0.8 - 0.95

Carrots

0.4 - 0.6

0.6 - 0.75

1.0 - 1.15

0.8 - 0.9

0.7 - 0.80

Cucumber

0.4 - 0.5

0.7 - 0.8

0.95 - 1.05

0.8 - 0.9

0.65 - 0.75

Lettuce

0.3 - 0.5

0.6 - 0.7

0.95 - 1.1

0.9 - 1.0

0.8 - 0.95

Onion Dry

0.4 - 0.6

0.7 - 0.8

0.95 - 1.1

0.85 - 0.9

0.75 - 0.85

Onion Green

0.4 - 0.6

0.6 - 0.75

0.95 - 1.05

0.95 - 1.05

0.95 - 1.05

Pepper

0.3 - 0.4

0.6 - 0.75

0.95 - 1.1

0.85 - 1.0

0.8 - 0.9

Tomato

0.4 - 0.5

0.7 - 0.8

1.05 - 1.25

0.8 - 0.95

0.6 - 0.65

Watermelon

0.4 - 0.5

0.7 - 0.8

0.95 - 1.05

0.8 - 0.9

0.65 - 0.75

The first crop reading is for high humidity and low wind conditions.

The second reading is for low humidity and strong wind conditions.

Source: Doorenbos and Kassam (1979).

1

2

Table 2: Crop coefficient (Kc) for various growth stages of selected vegetable crops.

Texture Class

Range

Average

Sand

30 - 65

49

Sandy Loam

90 - 123

106

Loam

155 - 172

164

Light Clay Loam

172 - 180

172

Clay Loam

155 - 172

164

Heavy Clay Loam

137 -155

147

For example, if the RAW for clay loam soil is set to be 80 mm of water (50% of total available), irrigation would be needed as soon as that amount is used. Note that the amount of water to be applied will depend on the depth of the crop's root system (Table 1).

Table 3: Available soil water in mm/m soil depth for different soil textures.

1.3 Crop coefficient (Kc)

2. Soil 2.1 Total and readily available water Ideally, a soil should hold enough water to facilitate plant growth and have the capability to drain away any excess. It is important to understand the way in which water behaves in the soil if irrigation efficiency is to be maximized.

Soils differ in their ability to store water, depending on their texture. Sandy soils hold the least because they have large pore spaces between the sand particles. Clay soils have much smaller pore spaces, giving them a greater water holding capacity. Most soil profiles are a mixture of the various texture classes, and the total water storage capacity depends on the cumulative storage capacities of the various layers within the profile.

Aggregate stability is another important factor, which indicates the ability of the soil to withstand structural breakdown during wetting.

28

industry Total available water (TAW), readily available water (RAW) and depletion fraction (p) are critical to planning an appropriate irrigation schedule. To maintain soil moisture at optimum levels, it is important to understand that not all of the total available water (Table 3) is used before the next irrigation is applied.

3. Climate data Climate data includes: Temperature, relative humidity, sunshine hours and wind speed.

The sum of water lost from the soil surface by evaporation and from the crop via transpiration is referred to as evapotranspiration and is abbreviated as ET. Water losses through ET are influenced by weather conditions such as temperature, wind, solar radiation and relative humidity, and are estimated from using these factors.

Using the moisture accounting method The moisture accounting method is illustrated by the following example (Table 4), of a tomato crop cultivated in a clay soil. As soon as the accumulated deficit exceeds 40 mm, a further irrigation is supplied.

To use the moisture balance sheet, complete the following steps: • Decide which crop will be grown (e.g. tomatoes).

• Estimate or measure root depth by digging a hole next to the crop, or alternatively use Table 1.

• Find out the soil type and determine total available water (see Table 3).

• Decide on an appropriate depletion fraction (p) roughly 0.3-0.5 for vegetable crops.

• Calculate readily available water = depletion fraction (p) × total available water.

• Calculate net irrigation application depth (mm) = root depth × readily available water.

• Record reference evapotranspiration (ETo) from climate data or calculate it from pan evaporation.

• Multiply ETo in mm/day (column A) by the appropriate crop coefficient (Kc) value (column B) to obtain crop water needs.

• Record daily rainfall and estimate effective rainfall (mm) (column D & E).

• Add up column H for all water deficits since the last irrigation and subtract effective rainfall. (After an irrigation event the soil is saturated and crop water use is assumed to be zero).

Crop: Tomatoes Soil type: Clay Month: January

Day

Effective root depth (D rz)= 0.55 meter (Table1), p = 0.4 (Table1), TAW = 180 mm/m (Table8), RAW = 0.4 × 180 = 72 mm Net irrigation depth = D rz × RAW = 0.55 × 72 = 39.6 (rounded to 40 mm) (see step 6)

A

B

C=A×B

D

E = D - 5mm

F

H = (E+F) - C

ETO (mm/day)

Crop coefficient (Kc)

Crop water use (ETc) (mm/day)

Rainfall (mm)

Effective rain (mm)1

Irrigation application dnet(mm)

Cumulative soil water deficit (mm)

1

7.6

0.85

6.5

0

0

0

-6.5

2

8.6

0.85

7.3

3.8

0

0

-13.8

3

8.6

0.85

7.3

0.4

0

0

-21.1

4

8.8

0.85

7.5

0

0

0

-28.6

5

7.1

0.85

6.0

0

0

0

-34.6

6

9.1

0.85

7.7

0

0

40

Irrigation

7

6.4

0.85

5.4

0

0

0

0.00

8

3.4

0.85

2.9

0

0

0

-2.9

9

6.2

0.85

5.3

6

1

0

-8.2

10

6.3

0.85

5.4

3.2

0

0

-13.6

11

4.3

0.85

3.7

4.6

0

0

-17.3

12

7.7

0.85

6.5

1.4

0

0

-23.8

13

8.7

0.85

7.4

17.8

12.8

0

-11.0

14

7.2

0.85

6.1

0

0

0

-17.1

15

7.0

0.85

6.0

0

0

0

-23.1

16

8.4

0.85

7.1

0

0

0

-30.2

To calculate effective rainfall, during spring, summer and autumn periods, subtract 5 mm from each of the daily rainfall totals.

Assume rainfalls of 5 mm or less to be non-significant (zero). In winter, all the rainfall is assumed to be effective.

1

Table 4: Moisture balance sheet for scheduling irrigation in a tomato crop.

Crop water needs The amount of water required to supplement crop water needs depends on the water requirements of the plants, local climate and soil conditions. Crop water needs can be estimated using weather data (evapotranspiration-based method). This method

allows growers or irrigation designers to estimate how much water will be required during the cropping season, and how best to deliver it to meet the crop's peak demand. This method is most effective when used in conjunction with other scheduling techniques.

30

oplossings gedryf deur advies saad | wetenskap | diens

Malis •

•

• • •

Vinnige, mediumgrootte botterslaai Maklik om te oes danksy sy gladde bodem Het ‘n pragtige blink groen kleur Mediumgroen blaar wat dik en bros is Stewige kop met goeie veldhouvermoë

| www.nuvance.co.za |

Rainbow • •

•

• •

‘Frilly’ slaai Goed aangepas vir herfs, winter en lente aanplantings Geskik vir die vars- en voorafverpakkingsmark Liggroen interne kleur Medium-groot koppe

SV 4896 LC • •

•

Geskik vir somerproduksies Geskik vir die varsen voorafverpakte mark Goeie skudblare, veldhouvermoë en siektetoleransie

Pinotage • •

• •

‘Oakleaf’ slaai Goed aangepas vir herfs, winter en lente aanplantings Rooigroen interne kleur Oesgereed na 45 tot 60 dae

access to premium products seeds | science | service

Hoplita*

SV 5047 CE* • • • • • • •

Plants have a very open structure Suitable for winter production Vigorous plants with short internodes Excellent fruit set Cylindrical and straight fruit High tolerance to Cca, Ccu Intermediate tolerance to CVYV, CYSDV, CMV, Px

• •

• • •

Vigorous plant Ideal for the summer months, but does also perform well during winter in the Lowveld Medium large fruit High tolerance of CVYV and Ccu Intermediate tolerance of CYSDV, Px, Cca

| www.nuvance.co.za |

32

hoplita komkommer – die regte keuse

artikel deur richard hansen

H

oplita* is `n F1 komkommer varieteit van Seminis wat die afgelope tyd in die Wes-Kaap baie in gewildheid toegeneem het.

Mnr. Johan van Zyl, van die Vredendal area, het Hoplita* laasjaar as `n proef geplant om te vergelyk hoe dit met sy bestaande varieteite kompeteer. Tydens die proefaanplanting het Hoplita* homself bewys waarna Mnr. van Zyl hom deelgemaak het van sy saaiprogram. Volgens Mnr. Van Zyl het Hoplita* die volgende uitstaande kenmerke: • hoë dravermoë sonder om sy vrugte te speen • konstante lengte van L/XL • eenvormigheid van vrugte regdeur die plant se groeifases • ’n uitstekende siektepakket (Hoë toleransie teen CVYC, Ccu en Intermediêre toleransie teen: CYSDV Cca en Px).

Met die mees onlangse aanplanting by Mnr. Van Zyl het Hoplita* tussen 4-5 vrugte per plant meer as die standaard varieteit geproduseer en kon al in sy vierde week na uitplant geoes word.

products

is pH perhaps the culprit? article by howard champ

I

t’s summer and in this awesome part of the world which also means that for a large portion of the agricultural sector it is prime growing season and the demand on our farmers to attend to their crops is endless, largely due to the pace at which the crops are growing due to the warm and often wet conditions.

Due to the pace of the current growing season, crops are vulnerable to a variety of pests and diseases and because of the ideal growing conditions experienced at this time of year farmers have to keep a close eye on any unwanted symptoms in their crops so that they can react swiftly to reduce any further potential yield losses.

Often at this time of year, we at Nuvance get calls from various farmers to help identify problems with their crops. In my personal experience of late, I have been asked to visit several different farmers concerned about symptoms in their crops that are occurring.

It can be quite challenging to pinpoint the cause of the symptoms and of course very disconcerting for the grower. Often disease symptoms and mineral deficiency symptoms can be confused and misdiagnosed. Great care is taken by the Nuvance sales representatives to investigate together with the farmer his/her cultural practices up until that point, to have a better understanding of the possible cause(s). It has become apparent recently that after in-depth discussions with the various farmers, that their cultural practices, including fertiliser and chemical application, mechanical maintenance are usually all up to scratch except for one, that is being overlooked namely soil pH! Farmers are fully aware of the importance of soil pH so there is no need to explain this, but often this can be overlooked and to save costs growers are tempted to rectify the pH ‘next season’. I have seen crops that have been well attended and money has been spent on correct fertiliser application but the crop at an early stage begins to show symptoms of specific mineral deficiencies.

Magnesium, for instance, does not like acidic soils and is less available to the plant at a certain pH whilst the majority of other minerals are still available to the plant and will indeed be taken up by the plant resulting

RANGE OF ACIDITY

RANGE OF ALKALINITY

The influence of soil pH on nutrient availability in an imbalance and this is when symptoms begin to emerge. The table below shows the availability of certain minerals under different pH conditions.

Ideally soil pH needs to be around 6.0 to 6.5 for optimum growing conditions, but you can already see that within this range the availability of ‘phosphorus’, ‘calcium’, ‘magnesium’ and the trace element of ‘molybdenum’ is reduced. Hydroponic growers are gauging the pH of their water, daily and this is optimum management when it comes to pH control. This is not a practical management tool for growers producing crops in the soil, so they are encouraged to have their targeted soil’s pH checked at least once annually.

Often these growers are under pressure to utilise their soils continuously and as a result of constant cropping and fertiliser application, the residuals can create a more acidic environment where certain minerals are no longer as effective as they used to be. Please remember to regularly submit soil samples to your preferred laboratory so that you can make an informed decision to rectify the soil pH, based on the test results. Some soils could be costly to rectify, but if not done, then the problem will only deteriorate even further, in other cases it may only be a case of light annual maintenance.

Goodluck!

34

bejo visits clearwater farms

F

or several years now, there has been a strong relationship between Mr Andre Dekker (Area Manager Africa & Middle East) from Bejo and Mr Steve Calaca from Clearwater Farms.

Clearwater Farms in Bapsfontein (Gauteng) is a large-scale commercial vegetable grower owned and run by the Calaca family. Here several of Bejo’s beetroot, carrot and brassica varieties are planted year after year with huge success.

What makes Clearwater Farms’ such a successful business is the correct variety choice, best farming practises and attention to detail. During a recent visit to South Africa, Mr Andre Dekker (Bejo) together with Mr Steve Calaca (Clear Water Farms) assessed the infield performance of some of Bejo’s flagship varieties.

Mr Andre Dekker and Mr Steve Calaca in a Boro field (left) and a field of Megaton (right)

products article by gawie buys

maragogi presteer weer in die noorde

36

products artikel deur harold lindeque

M

aragogi* het die afgelope uie seisoen weer mer­ kwaardelik presteer in die Noorde (Limpopo) se vroeë tydsgleuf. Soos in ‘n vorige uitgawe van die Oppiplaas gemeld, het ons weereens gesien dat Maragogi* sy man kan staan in die veld.

Sy kenmerklikke dun nekke en ongelooflikke hoë opbrengs was een van die merkwaardelikke einskappe wat Maragogi* in die veld laat uitstaan het. Maragogi* was verlede uie seisoen op die Springbokvlakte (middel Februarie) geplant en boere het groot sukses behaal t.o.v kwaliteit en opbrengs. Mnr Andries Groothof eienaar van Adaja Boerdery naby Settlers was uiters tevrede met Maragogi* oor die goeie kwaliteit wat hy kon bemark. Nietemin het Andries ook ‘n rekord opbrengs gehad waarmee hy natuurlik baie tevrede was.

Adaja Boerdery het ook baie kostes gespaar aangesien hulle 4 weke vroeër op die mark kon wees met ‘n uitstaande kwaliteit ui. Aangeheg is paar fotos wat geneem is van Maragogi*, vanaf plant, oes en uiteindelik oppad mark toe. Mnr Carel Crause, Adaja Boerdery se akkerbou bestuurder staan saam Harold Lindeque (Nuvance) by van die palette Maragogi* wat oppad mark toe is. Carel is ook baie tevrede oor hoe mooi die uie vertoon in die sakkies.

In kort opgesom, merkwaardig mooi.

advancing beyond the basics seeds | science | service

SV 1514 SK*

Messenger* • •

• • •

Strong plant Ideal for the summer months, but does also perform well during winter in the Lowveld Very good disease package with no rust marks on plants High packout rate and good tip fill Average ear length 19 - 22 cm

• • • • • •

Very high yield potential Excellent husk cover Strong root and stalk structure Ready to harvest 81 - 85 days after planting HR: RpG; IR: Pst,MDMV/SCMV

| www.nuvance.co.za |

38

products

sentinel sukses artikel deur heigers campher

N

a ‘n reeks suksesvolle proewe en grootskaalse aanplantings van die waatlemoen Sentinel regoor Limpopo, is dit duidelik dat hierdie varieteit ‘n wenner gaan wees vir die SuidAfrikaanse mark.

Onlangse marknavorsing het getoon dat die gewildste waatlemoene grote tussen 8 tot 12kg is. Sentinel val presies in hierdie kategorie. Sentinel is ‘n blokagtige, langwerpige waatlemoen met 'n donker, gevlekte strepe.

Tydens ‘n onlangse aanplanting van Sentinel by Mnr Bennie Riekert op Baltimore in Limpopo het Sentinel uitgestaan, danksy sy hoë opbrengspotensiaal, groeikragtigheid, eenvormigheid, goeie hou vermoë en interne kwaliteit. Intern is Sentinel dieprooi met ‘n vars sappige vleis. Sentinel is ook geskik vir die vervoer oor lang afstande danksy sy dik skil en langwerpige vorm.

advancing beyond the basics seeds | science | service

Batavia • • •

Medium sized broccoli Grey-green colour Suitable for spring to mid summer production

Basan • • •

Excellent quality Strong plant with upright growth habit Suitable for the fresh and processing market

Skywalker • • •

Suitable for the fresh market Good head protection Ready for harvesting in 90 days

Covina • •

Produces medium to dark green heads Suitable for the fresh and processing market

| www.nuvance.co.za |

40

verwelkoming: lindie oberholzer

regional news

L

indie Oberholzer het op 1 Julie 2019 as Nationale Produkontwikkelingsbestuurder vir blaargewasse by Nuvance aangesluit. Lindie het haar meestersgraad by die Universiteit van Pretoria voltooi waarna sy as taksonoom vir die Landbounavorsingsraad ge­werk het, die begin van ‘n beroep in landbou.

Daarna het sy op beide die landbouchemie en groentesaad kant van die bedryf gewerk asook op kommersiele plase waar sy waardevolle praktiese ondervinding op gedoen het.

As spesialis op wortels het sy gou-gou die naam “carrot queen” verkry maar het ook ‘n groot liefde ontwikkel vir koolgewasse. Sy het veral baie werk gedoen op seleksies van kool vir die Suid Afrikaanse mark en het ‘n draai in die UK gemaak om koolgewasse van naderby te bestudeer. Haar gewas spesialieite sluit in wortels, kool, beet en uie wat ‘n aanwins is vir die tegniese span van Nuvance.

Ons verwelkom vir Lindie by Nuvance en wens haar alle voorspoed toe.

verwelkoming: de wet meyer

D

e Wet Meyer het op 4 November 2019 as nuwe verkoopsverteenwoordiger vir die Noordwes streek by Nuvance aangesluit. De Wet het in 2011 aan die Hoërskool Waterkloof gematrikuleer.

Daarna het hy ‘n kwalifikasie in logistiek en vervoerbestuur verkry, terwyl hy as produksie en logistieke toesighouer gewerk het. In 2017 het hy by Hazera as verkoopsverteenwoordiger vir die Laeveld streek asook Mosambiek aangesluit. Hier het hy ondervin­ding opgedoen op sy spesialiteits gewasse naamlik tamaties en soetrissies. De Wet sien uit om saam met sy nuwe area te groei en aan sy behoeftes te voorsien.

Ons verwelkom vir De Wet by Nuvance, en wens hom alle sterkte en voorspoed toe!

success is in the detail seeds | science | service

Capture • • •

A medium sized cabbage Good heat and black rot tolerance Average head mass between 3 to 5 kg

Menzania •

• •

Large, round and slightly flat shaped head Good leaf coverage Good quality and uniformity

Pandion •

•

•

Baby cabbage suitable for year round production Ideal for the fresh and prepacked markets Ready to harvest 60 days after planting

Omero* • • •

Red baby cabbage Suitable for the fresh and pre-pack markets Average head mass of 0.5 – 1 kg

| www.nuvance.co.za |

42

sales

verkoopspan | sales team 08

09

04

01

REGION

06

10

02

07

05

11

12

03

CONTACT PERSON

CONTACT NO.

01

Western Cape

02

Southern Cape

03

Eastern Cape

04

Northen Cape

05

Mpumalanga

06

Gauteng

07

Limpopo

08

Bushveld

09

North West

10

Free State

11

Natal Midlands

12

Natal Coastal

EMAIL

SADC

Floris Kotze - Commercial Manager

082 604 0060

f.kotze@nuvance.co.za

SADC

Dr Quintin Muhl - Product Development Manager

072 612 7906

q.muhl@nuvance.co.za

SADC

Lindie Oberholzer - Product Manager: Leafy Crops

066 235 6494

l.oberholzer@nuvance.co.za

Richard Hansen - Sales Representative

082 666 0405

r.hansen@nuvance.co.za

Howard Champ - Sales Representative

082 574 3633

h.champ@nuvance.co.za

01 02 03 04

info@nuvance.co.za

05

Jacques Louw - Sales Representative

081 028 1747

j.louw@nuvance.co.za

06

Gawie Buys - Sales Representative

082 467 0577

g.buys@nuvance.co.za

07

Harold Lindeque - Sales Representative

064 656 1556

h.lindeque@nuvance.co.za

08

Heigers Campher - Sales Representative

082 443 5315

h.campher@nuvance.co.za

09

De Wet Meyer - Sales Representative

076 110 0799

d.meyer@nuvance.co.za

10 11 12

info@nuvance.co.za Anina Meyer - Sales Representative

ADDRESS

082 785 6697

CONTACT NO.

a.meyer@nuvance.co.za

EMAIL

Meadowdale DC 95 Fleming Street | Meadowdale | 1609

010 534 8147

meadowdale@nuvance.co.za

Brits 81 Tom Street | Brits | 0250

021 252 6849

brits@nuvance.co.za

Louis Trichardt 108 Industrial Street | Louis Trichardt | 0920

015 5164809

louistrichardt@nuvance.co.za

success is in the detail seeds | science | service

PS 16351609* • • •

Tolerant to Phytophthora capsici Extended harvest periods Improved marketable yield

Revelation • • • •

Good shelf life Average fruit size of 10 x 10 cm Blocky sweet pepper Suitable for the fresh market

Amarelo • • • • • • •

Green to yellow at maturity Medium large fruit Excellent quality Strong upright plant Good leaf cover Suitable for open field and nethouse production Good tolerance to PVY

SV 6131 PB* • • • • • •

Suitable for open field production Excellent leaf coverage for protection against sunburn Dark green fruit colour Uniform fruit with good leaf attachment Vigorous plant Excellent disease package

| www.nuvance.co.za |

44

The moment “lockdown” was announced; nobody rushed to buy gold, expensive gadgets, cars or other assets.

Everyone was worried about food.

This is why agriculture is considered the “mother of all culture”.

oplossings gedryf deur advies saad | wetenskap | diens

Boro • • •

Goeie toleransie teen blaarvlek Uitstekende somerkultivar Boro is geskik vir die verpakkingsmark

Manzu • •

•

Oesgereed binne 80 tot 100 dae Geskik vir die verpakkings- en bossiemark Goeie toleransie teen Rhizomania

Bettollo • • •

Aangepas vir koeler klimaat Ideaal vir die verpakkingsmark Bettollo het goeie toleransie teen blaarvlek

Subeto • • • • •

Medium-vroëe kultivar Regop groeiwyse Uistekende somerkultivar Geskik vir die varsmark Hoë toleransie teen blaarvlek

| www.nuvance.co.za |