Rust Bust Booklet by Bridget Penna

the

MANAGEMENT STRATEGIES to benefit you, your neighbour and your industry

www.rustbust.com.au

For rust support, 24/7...

Contents

www.rustbust.com.au Rust support 24/7

Contacts

Australian Cereal

Rust Survey Contacts:

Victorian Contact:

South Australian

inside front cover

The Rust Bust

The Rust Puzzle

Identifying rust Wheat rust diseases Barley rust diseases

6 7 8

Oat rust diseases

Contact:

How to manage rust

Variety selection

Green bridge control

Rust monitoring

Chemical support

Communication and biosecurity

Visit our website www.rustbust.com.au

Samples and Testing

Acknowledgements The Rust Bust is an initiative of the Australian Cereal Rust Control Program Consultative Committee, supported by the Grains Research and Development Corporation.

Australian Cereal Rust Control Program

How and where to send samples

Case Studies

Current research

Grower case studies

Glossary

Contacts

inside back cover

Useful links

back cover

the

Photos kindly supplied by Dr Grant Hollaway, Dr Hugh Wallwork, Dr Ian Dundas, Professor Robert Park, Dr Peng Zhang, Evan Collis, Ciara Beard, Belinda Cay, Alistair Lawson, Rebecca Barr and Bridget Penna. Information sourced from members of the Australian Cereal Rust Control Program Consultative Committee. Brochure written and edited by AgCommunicators Designed by Jane McLean Design September 2015

www.rustbust.com.au @the_rustbust

Stem rust is hard to treat in thick canopies where fungicides may not reach all parts of the stem

the

The Australian Cereal Rust Control Program Consultative Committee (ACRCP CC), with support from the GRDC, continues to support the ‘Rust Bust’ campaign. The campaign aims to raise awareness of the nature and importance of wheat rust management strategies. The ultimate goal is to encourage growers to phase out susceptible and very susceptible varieties from their rotation and to be more effective managers of rust diseases. The Australian Cereal Rust Control Program (ACRCP, established in 1973) monitors cereal rust pathogens throughout Australia, identifies and characterises new sources of rust resistance, and assists Australian cereal breeding groups to incorporate rust resistance into breeding lines.

The ACRCP is funded by the grains industry, through the Grains Research & Development Corporation (GRDC). The ACRCP Consultative Committee is a key link between industry and the ACRCP. The Consultative Committee has a wide scope for membership, which includes representatives from state pathology and breeding groups.

The Rust Puzzle

Rusts are caused by parasitic fungi which reproduce and thrive on green plant tissue.

Rust spores can also spread on clothing, footwear and machinery.

All rusts can cause significant yield loss in the right conditions. The earlier crops are infected, the greater the potential yield loss.

If a rust spore comes in contact with susceptible plant tissue, it penetrates and infects individual plant cells. RUST SPORE

The fungus releases airborne spores which are spread readily by the wind over large areas in a short time. Just one hectare of rust-infected wheat can produce 19.1kg of rust spores.

Resistant plants have an inbuilt genetic defence mechanism, which enables the plant to fight back and stop the growth of the invading rust.

PLANT CELL

INFECTION

Rust can impact your bottom line through lost crop production. Timing is critical â&#x20AC;&#x201C; monitor crops regularly.

Growers must carefully manage rust as it can mutate, change at the DNA level and overcome resistance genes. Varieties resistant to one pathotype may be susceptible to another. Check disease guides for up-to-date ratings.

Australian researchers are continually investigating the way pathogens mutate to ensure ongoing genetic resistance.

Identifying rust Rust diseases can attack wheat, barley, triticale and oats. Understanding specific details such as pustule shape and colour for each rust will help you to identify any in your crops.

Wheat rust diseases

Red brown pustules

small circular pustules

Long stripes of small yellow/orange pustules

Leaf Rust

Stem Rust

Stripe Rust

(Puccinia triticina)

(Puccinia graminis tritici)

(Puccinia striiformis tritici)

> The leaf rust fungus forms small circular or oval, orange/ brown pustules on the upper surfaces of leaves. Spores produced in these pustules can be rubbed off with your finger or a tissue.

> Stem rust is characterised by reddish-brown, powdery oblong-shaped pustules on stems as well as leaves, leaf sheaths and heads. Pustules on leaves will rupture on both sides of the leaf blade. The pustules tend to run parallel to the long axis of the leaf or stem. As the plant matures and towards the end of the growing season, the pustules turn black as stem rust teliospores are produced.

> Stripe rust typically forms long stripes of small yellow/ orange pustules on the leaf. In juvenile plants, stripes are not produced and individual pustules are similar to pale leaf rust. The pustules, which run parallel to the long axis of the leaf, consist of masses of spores. The spores can be easily rubbed off causing a yellow smear on your fingers.

> Later in the season, rust pustules may develop on leaf sheaths. As the crop matures, a different type of spore, which is black and called a teliospore, is produced. In the absence of an alternate host in Australia, the teliospores play no further role in disease development. > Leaf rust establishment is favoured by humid conditions and temperatures of between 15°C - 25°C.

> Stem rust and leaf rust can be misidentified. Points of difference include pustule size (stem rust pustules are usually larger), colour (stem rust pustules are usually darker), and leaf rust occurs mostly on the top of the leaf. > Barley, triticale and durum wheat can also be attacked by wheat stem rust. > Under favourable conditions, complete crop loss can occur in susceptible varieties. > Stem rust prefers warm (>20°C) and humid conditions and will often not be visible in a crop until late spring and early summer.

> Stripe rust is less damaging than stem rust, but suitable conditions for stripe rust infection occur regularly. Barley grass and volunteer wheat plants are good hosts of wheat stripe rust. > Of the three wheat rusts, stripe rust is best suited to cooler temperatures that occur from autumn to early spring. Once an infection is established, the fungus can survive temperatures as high as 40°C. > Generally, stripe rust infection is possible as long as night time temperatures are below 20°C (optimum 6°C - 12°C) with a minimum of three hours of leaf-wetness.

Oat rust diseases

Leaf Rust

Stem Rust

(Puccinia hordei) > Barley leaf rust is visible as small circular to oval pustules on the upper surfaces of leaves, which produce a mass of brown powdery spores. Rust pustules also develop on leaf sheaths and awns. > Unlike other cereal rust pathogens, in some parts of Australia the barley leaf rust pathogen can survive between seasons by infecting its alternate host, the winter flowering bulb, Star of Bethlehem (Ornithogalum umbellatum). > Another type of rust spore is produced on the weed that infects barley. The rust can now complete its life cycle allowing it to potentially create new combinations of virulence. > Sowing barley into paddocks where the Star of Bethlehem is present is not recommended. This plant is a common weed in some areas of the Yorke Peninsula in SA.

> Three forms of stem rust attack barley: wheat stem rust (Puccinia graminis tritici), rye stem rust (Puccinia graminis secalis) and a hybrid of the two. The three forms look identical, both in terms of the symptoms they induce (see previous description for wheat stem rust) and in morphology as revealed under a microscope. > Warm temperatures between 15°C - 30°C and humid conditions are required for infection. > Barley is more readily infected over summer than during the regular growing season. This means that barley can be a serious over-summering host for wheat stem rust.

S RU

US R N

Barley rust diseases

Stripe Rust

Crown Rust (Leaf Rust)

Stem Rust

(Puccinia striiformis hordei [not present in Australia])

(Puccinia coronata avenae)

(Puccinia graminis avenae)

> Circular to oblong pustules on the upper surfaces of leaves produce a mass of orange powdery spores which readily disperse. Pustules may also develop on the leaf sheaths and the glumes.

> Large, dark reddish-brown pustules may be seen on the leaves, leaf sheaths, stems or heads in oat stem rust. These pustules contain a mass of powdery spores which shed easily.

> The name crown rust comes from the characteristic shape of the spores when viewed under a microscope and not the parts of the plant that are infected.

> Oat stem rust also attacks wild oat. Wild and volunteer oats are carriers of the disease from one season to the next.

> This form of stripe rust which specifically infects barley has not been detected in Australia as yet and poses a big risk to the Australian barley industry. A form of stripe rust which occurs on barley grass can infect some barley varieties. > Symptoms of barley stripe rust are similar to those of wheat stripe rust. Yellow to orange spores form in pustules in stripes along the leaf. In young leaves, the pustules are scattered on the leaf. > Suspected barley stripe rust infections should be reported immediately to your regional pathologist.

> Crown rust and stem rust look similar in oats. The differences are that you do not usually see crown rust on stems. Crown rust pustules are smaller, orange, and do not rupture on both surfaces of the leaf to the same extent as stem rust. > The disease is more severe in seasons where summer-autumn rains allow the fungus to survive on volunteer and wild oats. > Infection is encouraged by moist conditions and temperatures between 15°C - 22°C. The disease is most severe when an epidemic starts in autumn in early sown crops when temperatures are still warm. > Crown rust can cause losses of up to 50% in forage, hay and grain yield. It may also reduce the palatability of forage and hay.

> Infection requires warm temperatures of between 15°C - 30°C and moist conditions.

ve rust? nt a h u o y if e r Not su tate pla s r o t is m o n o agr nd Contact yourwho can help identify a pathologist the disease for you. confirm

> Infection is favoured by moist conditions with temperatures around 15°C. Crops sown early when nights are still warm are often more severely infected.

How to manage rust

STEP 1:

Make a strategic variety selection

STEP 3:

> Know your rust risks

> Rust is a social disease > If you have a rust outbreak, discuss management options with your neighbours > Follow basic biosecurity measures, e.g. clean clothes and boots and washing down machinery to limit the risk of spread > Let your agronomist and state plant pathologist know if you find rust

Communicate

> Check your varietyâ&#x20AC;&#x2122;s rust resistance ratings on the Rust Bust website www.rustbust.com.au > Understand all-stage vs adult plant rust resistance as this impacts your crop management e.g. chemical control, monitoring, etc > Consult with your agronomist and/or plant pathologist for support

STEP 4:

STEP 2: Management Resistant varieties

Susceptible varieties

> Remove all volunteer cereals and weeds, the green bridge, at least four weeks before seeding

> Remove all volunteer cereals and weeds,the green bridge, at least four weeks before seeding > Consider using an in-furrow fungicide or seed treatment to protect early growth > Monitor crops at seven to 10 day intervals from early stem elongation > Apply foliar fungicide, either as preventative or as soon as rust is detected (from the start of stem elongation to flag leaf emergence) > Tailor your fungicide use depending on variety resistance, rainfall zone, growth stage, rust type and seasonal conditions > Make sure you observe maximum residue limits and withholding periods

> Consider using an in-furrow fungicide or seed treatment to protect early growth in varieties with Adult Plant Resistance > Monitor crops at least fortnightly during growing season

Submit a sample â&#x20AC;&#x201C; itâ&#x20AC;&#x2122;s for the industry good! > The Australian Cereal Rust Survey is free > Postage paid envelopes are available > Your sample can help identify new rust pathotypes or the spread of the disease > Play your part in national rust management

The Rust Bust encourages growers to phase out susceptible (S) or very susceptible (VS) varieties from their farming systems.

Variety selection

How to make a variety selection to combat rust While we all want the highest yielding variety, when it comes to rust, you must choose wisely. Keep in mind the potential impact of a rust outbreak in your crop and the costs you would be faced with in terms of time, fuel, chemicals and reduced yields. Each year, the state government agriculture departments release guides which outline the rust resistance ratings for each variety. A stripe rust outbreak in susceptible (S) and very susceptible (VS) varieties could cause a yield loss of 65% or more compared to growing a rust resistant variety. To make things easier, there are tables on www.rustbust.com.au which are searchable to highlight your current variety and its known resistance rating to stem, stripe and leaf rust. You can also choose to sort the table by resistance rating to look at varieties which may work best for your conditions.

Minimum Disease Resistance Standards The ACRCP Consultative Committee recommends Minimum Disease Resistance Standards for wheat rust management, taking into account the impact of regional differences in climate on rust development.

The recommended minimum levels of resistance required for wheat

Resistance classiﬁcation and average yield loss from stripe rust infection in a Victorian trial RATING

DEFINITION

AVERAGE VIC YIELD LOSS %

Resistant (R)

The disease will not multiply or cause any damage in this variety. This rating is usually only used where the variety also has all stage resistance

Moderately Resistant (MR)

The disease may be visible and multiply but no signiﬁcant economic yield losses will occur

Moderately Resistant-Moderately Susceptible (MR-MS)

Rust can establish early and an epidemic can develop from these infections. The level of resistance may improve as the crop develops, although losses of up to 20% can be expected if fungicides are delayed or not used.

Moderately Susceptible (MS)

Disease may develop at any stage of crop growth and leaf area damage can be high, leading to serious crop losses if left unchecked

Moderately Susceptible-Susceptible (MS-S)

Disease can develop rapidly at any growth stage with high crop yield loss potential.

Susceptible (S)

The disease can be severe at any growth stage on these varieties. Losses of more than 50% are likely if the disease is not controlled.

Very Susceptible (VS)

This variety should not be grown. Losses ranging from 50-80% can be expected.

Average yield losses in the presence of stripe rust in varieties with different stripe rust ratings in south-eastern Australia during 2005, DEDJTR, Victoria This classiﬁcation is only a general guide.

REGION Northern (Queensland and northern New South Wales) South-Eastern Region (southern New South Wales, Victoria and South Australia) i) Conventional spring wheat ii) Long season and early sown (before mid-April) wheat Western (Western Australia)

Resistance to rusts There are two types of resistance: all stage resistance and adult plant resistance. Plant breeders may use one or both of these genetic resistances when developing a variety. All stage resistance: This resistance is mostly “race” specific, meaning that it is effective against some pathotypes (races) of rust but not against others. Typically, when all stage genes are first deployed, they are completely effective. Through mutation of the rust pathogen, these resistances can be overcome, which causes previously resistant varieties to become susceptible.

STEM

STRIPE

LEAF

MR-MS

Adult plant resistance (APR): APR genes are partial resistance genes that work by slowing down the rate of epidemic development, rather than stopping the disease progress completely. They are often referred to as slowrusting or minor resistance genes. Most Australian wheat varieties carry one or more APR genes against stripe rust. In general, the resistance increases with the plant age and as the temperature rises. Therefore, in varieties that have APR as their only source of resistance, it is worthwhile protecting the earlier growth stages of the crop with seed or fertiliser treatments and/or in-crop fungicide application(s).

Rusts generally require living host tissue to survive. They can only persist from one season to the next on a living host, the â&#x20AC;&#x153;green bridgeâ&#x20AC;?.

now? k u o y Did crop, anaged

Rust does not survive on seed, stubble or soil. Elimination of the green bridge is therefore an essential element of rust management. The green bridge is rust-susceptible weeds and crop volunteers that grow/survive in paddocks, along fence lines or roadsides or around sheds and silos during summer/autumn. The more susceptible volunteer wheat plants there are growing during summer and autumn, the greater the risk of a rust epidemic. Late summer rain and early autumn rain will increase the green bridge risk. The green bridge risk is also higher when there are more weeds during summer/autumn surviving to the start of the new growing season. High levels of rust on the green bridge increases the probability of rust pathogens mutating which in turn places pressure on the genetic resistance of that variety.

Control of the green bridge

In the four to six weeks before seeding, there should be no green bridge in or around paddocks to be sown. It is critical that all volunteer host plants are removed either by cultivation, heavy grazing and/ or herbicides in the four week period leading up to sowing. One well infected plant can generate enough spores to initiate a serious rust outbreak in a nearby crop. It is also important to control host weeds during the growing season to prevent seed set that could contribute to green bridge development in the next fallow period. Effective control of the green bridge requires a community approach rather than an individual effort. Windborne spores can travel long distances so farmers need to work collaboratively to ensure regional control of the green bridge.

m ed A poorly ith uncontroll w d e ers in combin volunte e g id d up r green b tumn, can buil ing u a r/ creas summe vels, in of le m lu cu at high ino ust risk and th r r . r u u o o y ighb your ne

Green bridge control

How to manage the green bridge

Rust Monitoring

Are you monitoring crops at every growth stage? INSPECTION POINTS

It is critical to monitor all crops for the presence of rust, particularly during warm spring conditions. This can be done by either visually assessing the thicker patches in a crop or by walking in a W shape through the paddock to ensure inspection is representative of the whole paddock. Visually inspect ﬁve plants at 10 different locations. Inspect the lower parts of the plant, the stem and the leaves for symptoms. Monitor susceptible crops at seven to 10 day intervals from early stem elongation or from flag leaf emergence if seeding fungicide treatments have been used. If a fungicide has been applied, monitoring must start in the week before the protection period is expected to end.

heck Crop Cocations • 10 l lants • 5 p eful check • car

Most varieties will require continual monitoring, even if there has been a seed treatment or in-furrow fungicide used at sowing. Growers cannot afford to miss the early detection of a rust outbreak as epidemics can be explosive in susceptible varieties.

Early detection allows early preventative management.

This graph is a comparison of a stripe rust incursion on a VS variety and R variety assessed at weekly intervals. In two weeks, 55% of the VS variety’s leaf area was affected.

100 90 STRIPE RUST SEVERITY (%LEAF AREA AFFECTED)

Monitor your crop to detect infection at the earliest stage possible

Do you know just how costly a two week gap in monitoring your susceptible variety could be? +7 days = 55%

80 70 60 50

+7 days = 8%

40 30

+7 days = 0%

20 10 0 1-OCT

8-OCT

15-OCT

22-OCT

29-OCT

DATE Mace (SVS)

Livingston (R)

Stripe Rust Severity in 2013 (Joshua Fanning DEDJTR Victoria 2014)

Understanding when you need a fungicide

Upfront disease control

Foliar fungicides

Upfront fungicide treatments on seed or in-furrow and fertiliser applications can provide protection for the emerging crop, particularly relevant for MS to S and varieties which rely solely on adult plant resistance (APR).

Foliar fungicides applied at the start of stem elongation through to flag leaf emergence (growth stages GS30-39) are important to protect key leaves.

For stripe rust, treatments will delay the epidemic for varieties which have poor rust resistance. It is likely that in-crop fungicide will still need to be applied to protect the upper leaves of the canopy. Given the mostly later onset of leaf rust, the active ingredients in upfront treatments may have limited effect on leaf rust relative to stripe rust. Currently there are no upfront treatments registered for stem rust. It is important to note regional differences:

The requirement for in-crop fungicide sprays will depend on the carryover of rust inoculum on the green bridge, the timing of the epidemic in relation to the growth stage, and the level of resistance in the variety.

Be aware: > Fungicides are generally less effective at controlling stripe rust and stem rust when head infection occurs. > Fungicides are less effective on stem rust especially in thick canopies where fungicides may not reach all parts of the stems. > Fungicides may not always be available due to heavy demand or because weather conditions prevent application at an appropriate time. > It is important that growers do not simply rely on chemical management as this increases the risk of fungicide resistance in the pathogen.

> Upfront treatments can be a cost effective option for shorter season scenarios where there is early infection.

Chemical Support

Fungicide application. Timing is everything.

The actual economic response to fungicide application that occurs in the ďŹ eld will depend on many factors, including: > the timing of the rust outbreak in the crop, > seasonal conditions, and > the pathotypes of rust occurring in a region. After a fungicide application, crops should continue to be monitored as fungicides provide only two to four weeks protection. The GRDC Fact Sheets, Cereal Fungicides and Fungicide Timing, are particularly useful in explaining the most effective disease management strategies using fungicides.

> For longer season scenarios with higher rainfall, upfront treatments generally do not deliver full protection to the three upper-most leaves of the canopy (flag, flag-1 and flag-2) but still provide early season protection.

est andlian v r : a N h O I CAUT sure all pre the Austra en to rowers tions adhere nly registered ing g t a h t Use o includ pplica ntial It is esseest chemical ae of Practice.mmendationsust observe rv m co Cod post-haain Industry ve all label reiods. Growers considering Gr nd obser ding per ly whenwering to r l a a l o s u h t c h i c t t produ ates and wi Limits par ps in the flo . label r mum Residue cation to cro in the season Maxi gicide appli stages late fun grain fill

Foliar fungicides represent the last line of defence after other measures such as variety selection and seed treatments. Controlling and limiting damage from rusts with fungicides needs to be tailored to the variety resistance status, growth stage, the rust pathotype and seasonal conditions.

Found rust? How to prepare samples for dispatch

Rust is a social disease – it has no boundaries.

The Australian Cereal Rust Survey is funded through grower levies via the Grains Research and Development Corporation (GRDC). There is no cost to you for submitting a sample for analysis but the benefits are great.

It only takes one person in the district growing S or VS varieties with no control for a rust outbreak to occur.

The better the sample you collect and the more information you provide on the dispatch form will assist in understanding pathotypes and geographic distribution of rust in a particular season. Play your part in national rust management and assist the Australian grain industry by sending good samples.

Here’s how to collect a good sample*: > Ensure active rust infection. It is important that the sample material is actively producing spores. When you wipe over a leaf or stem with a tissue or white cloth, you should see yellow, brown or black dust-like smearing. If you are going to apply an in-crop fungicide, collect a sample first! Rust can spread rapidly from one farm to another and over hundreds of kilometres, via wind or on clothing and machinery. Actions by one person can have an effect on others, making rust a ‘social’ or ‘public risk’ disease. Regardless of the controls used, maximum benefits occur if all farmers adopt effective farm management strategies.

> As soon as you return from your trip (or preferably prior to returning), all clothing should be thoroughly laundered in hot, soapy water and footwear thoroughly cleaned.

Biosecurity – come clean, go clean.

Likewise if you have visitors from overseas or interstate it is best to minimise their contact with any growing crops unless you ensure appropriate precautions are taken. If they are going into a crop production area, ensure their clothes and footwear are clean and offer to provide them with clean clothing and footwear.

Good hygiene can stop the spread of spores hitching a ride on clothing, shoes or machinery into other regions. > If you are visiting crops outside your region (especially if traveling from the east coast to Western Australia), or returning from an overseas field trip, your potential to introduce an exotic pathotype or species needs to be taken seriously.

> When you return to Australia, make sure you let customs know you have been on a farm during your trip.

> Collect a sufficient sample. For leaf and stripe rust, this is 10cm of leaf completely covered by rust pustules. For stem rust, this is 10cm of 100% infected flag leaf sheath or 5 x 10cm peduncles with 100% infection. Collect enough leaf or stem material to meet the required sample size, for example, 10 leaves each with 10% stripe rust infection. > Collect material while the leaves and stems are dry. > Record the GPS location of the sample, preferably with latitude and longitude in decimal degrees. A bad sample, which has an insufficient sample size, low infection levels or is stale, is more likely to have lower spore germination and will potentially fail testing. Samples from early in the season are also critical as they could allow the early detection of a new pathotype.

Sending your sample and keeping it fresh: > Fold leaves infected with rust in half from top to bottom so the rust is on the inside. > Place straight stems and/or folded leaves into paper envelopes - do not use plastic wrapping or plastic lined packages. > If you are sending multiple types of rust samples at once, place each in a separate paper envelope. > Complete a dispatch form for each sample with geo-referencing for mapping and epidemiological modelling. > For further details visit http://sydney.edu.au/ agriculture/plant_breeding_institute/cereal_rust/ reports_forms.shtml#df > Contact the Plant Breeding Institute and they will send some Reply Paid envelopes to send your samples in. Alternatively, you can use the address below and follow the above guidelines to send a sample.

: PLES TO M A S D SEN ney y of Syd

it Univers al Rust Survey ere C n a li 76 Austra aid 880 Reply P 567 2 W n NS Narella

*Information sourced from: Plant Breeding Institute Cereal Rust Report, volume 11, issue 3, 10 September 2013, http://sydney. edu.au/agriculture/documents/pbi/cereal_rust_report_2013_ vol_11_3.pdf

Post your samples to the Australian Cereal Rust Survey as soon as possible. A sample that has been sitting on the dashboard of your vehicle for a week is likely to be dead!

Communication and biosecurity

Talk to your neighbour

Case Studies

Ug99? f WHATinI1S999, a new peaothnoetyopfethoe

If the Ug99 stem rust arrived in Australia tomorrow, a number of the country’s wheat varieties would be susceptible and have no effective resistance to this debilitating disease. Thankfully, scientists like Dr Ian Dundas from the University of Adelaide’s cereal cytogenetics laboratory are working on preventing this occurring by finding new rust resistance genes to be bred into modern wheat varieties. For several years, he has been investigating wild wheat relatives from around the world to find suitable resistance “We cannot afford genes to stem, leaf and to be complacent stripe rust in the hopes of as rust can mutate successfully transferring and evolve and that resistance into Australian and international can affect any of wheat varieties. the existing wheat

varieties...”

“When we share a resistance gene with plant breeders, we request that they don’t use any one gene on its own, but rather in combination with another effective stem-rust resistant gene to extend the durability of the resistance effort.” Dr Dundas explains that the most practical, costeffective and environmentally friendly way of protecting wheat crops from the rust diseases is through the use of resistant varieties. “We cannot afford to be complacent as rust can mutate and evolve and can affect any of the existing wheat varieties,” he said. “Many growers rely on fungicide for rust control and spray as a matter of course however fungicides will not always be an option. Plant diseases are best controlled preventatively. High yielding and rust resistance must be characteristics developed together in a wheat variety.”

To date, his team has already sent at least nine Ug99-effective rust resistance genes from his Adelaide base to wheat breeders in 14 countries, including Pakistan, Kenya, South Africa, Iran and India, for incorporation into locally adapted breeding lines.

In addition, Dr Dundas explains the importance of global food security and Australia’s role in ensuring the security of food to the poorest nations.

“The best place to find effective resistance genes is in the wild related species which are usually found in Middle Eastern countries,” he said.

“The Ug99 rust spread rapidly. Rust spores are carried in the wind and on clothing so travellers to Africa could potentially bring the disease back into Australia.

“Because grassy relatives of wheat have been growing out in the tough wild environment, only the hardiest and most disease resistant plants survive, however they also possess a lot of weedy characteristics such as low yield and poor quality which make them unsuitable for commercial production. The aim is to incorporate a segment of the alien chromosome into a modern wheat chromosome and to then refine the genes down to only include those incorporating the rust resistance.

PHOTOS: DR IAN DUNDAS

Researcher: Wild wheats being tamed to provide rust resistance

, a, Africa overcam enes In Ugand t appeared that st resistance g otype s ru th a ru m p m te is s te h s ely used uction. T , Ug99 most wid orld wheat prod g99. Since then ng ri w U u o e in b (Sr31) n the nicknam da into neigh t as n was give oved out of Uga a and as far eas rust has m s of east Afric frica. Like all g countrie own to South A and is developin d d d te n le a ta b u n a ap Ira sm (races) c ns, it ha pathoge ew pathotypes er important n th to in oming o of overc istance genes. res

“It is our global responsibility to provide the rust resistance genes to any country which requests them, ultimately it is in Australia’s interest to prevent these rust diseases entering the country,” he said.

“This is an international problem with an international response. Our stem rust resistant lines are being shared with international researchers with the goal of protecting the food supply of the world’s poorest people. “Rust is always going to be present and is continually evolving, so the wheat varieties grown need to evolve also to continue to offer resistance.”

The aegilops peregrinum plant – one of the wild wheat varieties Dr Ian Dundas (right) is using in his research.

impact e h t n e e s d n erseas a aims to make v o d e ll e v a r t rch ing “My tip: Havad on farmers, my reseave adequate genetic rust has h an wheat varieties ha t underpin my work sure Australie varieties growers seleche industry good.” resistance. Tdh to work together for t – we nee

Case Studies

Seeing a header turn red from stem rust dust has left a lasting impression on 81-year-old Wolseley farmer Max Brown. He can easily recall the sight of headers changing colours during the 1973 and 1974 stem rust epidemics, which caused an estimated $300 million damage1 across South Australia and Victoria. This is equivalent to $2.65 billion in today’s terms2. “We had a great looking crop and there was just nothing left when we reaped it,” he said.

“We listen to our agronomist and keep in close contact with him and know what’s going on...”

“We would have been expecting 20 bags (4 tonnes/hectare) and in the end, it went just 4 bags (0.8 tonnes/ hectare). In that year, we had a total crop of 61 tonnes. The previous year was 200 tonnes. It just demolished the crops. And it was common, everybody was experiencing the same thing.”

Max and his son Steve farm two properties near Wolseley in the State’s upper south-east, grazing sheep and cropping. On their home block of 555 hectares, they grow Mace wheat, barley, canola and beans.

PHOTO: ALISTAIR LAWSON

Grower: Max and Steve Brown – remembering the bad old days The 1974 stem rust epidemic is not the only one Mr Brown’s sharp mind can recall. While at school in 1947, he remembers helping his father during the holiday period. “The crops looked good until about six weeks before harvest. We had a big rain in October and that was the end of it. I remember we had a harvester where you could hear the grain rattling around as it came in. That year, it was silent. There was just no grain there.” Son Steve explains they don’t need to do any summer spraying as the sheep graze, hence reducing any risk of a green bridge carrying rust inoculum from one season to the next. They do, however, treat the seed and put out a treatment with the fertiliser to manage rust (predominantly stripe rust as they grow Mace which is S-VS), and follow up with two sprays during the growing season. “These days, it’s a given that you’re going to spray,” Steve said. “Years ago, we used to monitor and look for stripe rust hot spots, but these days we spray reasonably early to minimise the chance of any stripe rust developing. “Our first spray in usually around July or August, of a tebuconazole spray. We then use a second spray treatment around September/October. “We listen to our agronomist and keep in close contact with him and know what’s going on.”

Max & Steve Brown

Industry biosecurity plan for the grains industry: Australia’s Preparedness for Ug99, Prof. Robert F Park and Plant Health Australia, October 2009, accessed online http://www.planthealthaustralia.com.au/wp-content/uploads/2013/03/Wheat-stem-rust-Ug99-Business Continuity-Plan.pdf

The Reserve Bank of Australia’s Inflation Calculator calculates the change in cost of purchasing a representative ‘basket of goods and services’ over a period of time. http://www.rba.gov.au/calculator/annualDecimal.html

we take a so o d n ca st ru e g a m the da “0ur tip: We’ve see.nWe seek the help of an agronomist and proactive approach program in our management plan.” include a spray 25

Case Studies

Having seen how devastating a stripe rust outbreak can be, John Minogue takes variety selection very seriously. The susceptibility rating to rusts is the first thing he looks at when choosing which wheat to grow on his 2000 hectare property at Barmedman, between West Wyalong and Temora in New South Wales.

“Since we have changed varieties and since we have implemented a fungicide control program, we haven’t seen rust for three or four years...”

“In the early 2000s, we had a year where stripe rust devastated huge amounts of crops,” he said. “We had to spray and if you couldn’t get onto your land, you had to get a plane. If you couldn’t get a plane in time, the stripe rust just took over. It was widespread in the region and yields were very low as a result.”

Since then, John has changed varieties to get as much stripe rust resistance as possible. He plants EGA Wedgetail (MS) and Wylah (MS) for grazing sheep and cattle and is changing over from Spitfire (MR) to Suntop (MR-MS) and EGA Gregory (MR) for commercial cropping. John also has an active management strategy in place to prevent rust outbreaks. “Because of the resistance ratings in Suntop and EGA Gregory and because the resistance they have is adult plant resistance, we treat the seed with triadimenol to give it seedling protection until the adult plant resistance kicks in,” John said.

devastating w o h st ju g in w o n K : “My tip d in me not e lt su re s a h e b n ca rust grow I s ie t e ri a v e h t g in g only chan mend to m co re I s ie t e ri a v e h t but also selection ty e ri a v y m w o n k I . clients e industry.” ir t n e e h t n o s ct a p im

“We generally find we don’t have to apply any other treatments in-crop, but every time we’re in the crop, we’re checking for diseases, so we’re monitoring at least fortnightly during the growing season. “With the grazing varieties, we treat the seed with a fluquinconazole based product to provide early protection and when we remove the livestock after grazing, we top this up with an in-crop fungicide spray.” As an agronomist, John is also regularly monitoring crops for a group of clients within a 150 km radius. They provide him feedback on the development of any disease. “Since we have changed varieties and since we have implemented a fungicide control program, we haven’t seen rust for three or four years,” he said. “There’s been a huge change in varieties and it’s helping to control the green bridge too. Resistant crops have resistance volunteers so we don’t tend to have the inoculum loads that we have had in the past. “Last year, we had a very early start to the season and not everyone had controlled the green bridge so we expected to see a lot of rust, but thankfully we didn’t. I think farmers are more aware of how important variety selection is and managing their crops to keep the risk of rust down.”

John Minogue

PHOTO: REBECCA BARR

Grower: John Minogue - how to manage rust effectively

Glossary Adult plant resistance

Some varieties are susceptible to early disease as seedlings and then develop resistance as the plant matures. Depending on the variety, the resistance can be first detected at different growth stages or under different environmental conditions. Generally, the resistance increases with plant age and as the temperature rises. The resistance is controlled by minor genes that work in a number of different ways but the effect is to slow down the rate of disease development.

Epidemic

This term describes the increase and spread of a disease through a crop, district or region.

Exotic

This is used to describe a pathogen isolate (in this case rust) that has been introduced into Australia from somewhere overseas.

Germplasm

Germplasm in this context refers to the plant material that is used by plant breeders – it includes the plants used as parents for crossing, breeding lines under development, and established varieties.

Green bridge

The term ‘green bridge’ describes the weeds and crop volunteers that establish during the noncropping phase that help pests and diseases cross from one cropping season into the next. This mass of vegetation grows in paddocks, roadsides and non-crop land after summer rain or under irrigation. The green bridge is particularly important for diseases like rust or pests that cannot survive through the summer without a green host.

Incursion

The appearance of a new pathogen or pest in Australia, which has come from somewhere else.

Inoculum

A pathogen, a disease causing organism, that can cause infection when transferred through inoculation.

Inoculation

The process of applying a pest or pathogen onto healthy plants to generate disease.

Long season wheat

Wheat varieties are generally classified as either spring wheats, or long season (winter) wheats. The latter require a period of cold temperature at crucial growth stages to induce flowering - because of this, they are often sown earlier than spring wheats, and remain in the ground longer (hence “long season”). Wheats that are sown earlier in the season are potentially a concern in providing a green ramp – rust inoculum can move from the green bridge onto the green ramp, and from there into spring wheat crops.

Mutation

A change in the DNA of a plant, pest or pathogen that changes its genetic composition. Mutations occur in all organisms and are a random process. In rust, the most well-known case of mutation is where a pathotype mutates and acquires the ability to overcome a resistance gene in a variety, rendering it more susceptible. In the case of rust, it is generally a change in the expression of virulence that allows it to overcome resistance in a plant. It could also be a change that increases fitness or environmental adaptation in the rust pathogen.

Pathogen

A pathogen is a disease-causing organism (life form).

Pathology

The area of science that deals with studying and managing diseases.

Pathotype

A particular variant of a pathogen.

Pustule

The part of the rust pathogen that emerges through the leaf or stem of the plant. It is visible as a mass of fungal spores that are released and spread the disease to other plants.

Spores/ urediniospores

Rust produces spores in pustules that vary in shape, size and colour depending on the type of rust – leaf, stem or stripe. The urediniospores (aka urediospores) move readily on the wind and are responsible for rust transmission between plants, within fields and across large regions.

Teliospores

In high disease pressure and as crops begin to turn, darker coloured spores become evident as teliospores (aka teleutospores) are produced. The teliospores are resting spores, which do not have any function in wheat rust and oat rust pathogens in Australia.

Ug99

In Uganda, Africa, in 1999, a new pathotype of stem rust appeared that overcame one of the most widely used stem rust resistance genes (Sr31) in world wheat production. This pathotype was given the nickname Ug99. Since then, Ug99 has moved out of Uganda into neighbouring countries of east Africa and as far east as Iran and down to South Africa. Like all rust pathogens, it has mutated and is developing into new pathotypes (races) capable of overcoming other important resistance genes.

Virulence

Virulence is the ability of a pathotype of rust to overcome the resistance effects of a gene in the host. For example, the resistance gene Lr24 was effective in Australia in providing protection in wheat to leaf rust from 1983 until 2000. In 2000, a new pathotype with virulence for this gene was detected, and many cultivars with this resistance gene were rendered susceptible.

Contacts ACRCP Consultative Committee Chairman:

New South Wales Contacts:

Dr Dan Mullan Wheat Breeder InterGrain, Bibra Lake WA. Phone: 08 9419 8021 Email: dmullan@intergrain.com

Dr Andrew Milgate ACRCP Consultative Committee Secretary Research Scientist – Plant Pathology NSW Department of Primary Industries, Wagga Wagga Phone: 02 6938 1990 Email: andrew.milgate@dpi.nsw.gov.au

Australian Cereal Rust Survey Contacts: Professor Robert Park Director, Australian Cereal Rust Control Program Judith and David Coffey Chair in Sustainable Agriculture Plant Breeding Institute | Faculty of Agriculture and Environment The University of Sydney Phone: 02 9351 8806 Email: robert.park@sydney.edu.au Dr Will Cuddy NSW Department of Primary Industries Elizabeth Macarthur Agricultural Institute, Menangle And Plant Breeding Institute, the University of Sydney, Cobbitty Phone: 02 9351 8871 Email: will.cuddy@dpi.nsw.gov.au Web: www.dpi.nsw.gov.au/biosecurity

Victorian Contact: Dr Grant Hollaway Senior Plant Pathologist - Cereals Department of Economic Development, Jobs, Transport and Resources, Horsham Phone: (03) 5362 2111 Email: grant.hollaway@ecodev.vic.gov.au Web: www.agriculture.vic.gov.au

South Australian Contact: Dr Hugh Wallwork Principal Scientist, Cereal Pathology Plant Research Centre, Urrbrae, SA Phone: 08 8303 9382 Email: hugh.wallwork@sa.gov.au

Dr Steven Simpfendorfer Senior Research Scientist NSW Department of Primary Industries, Tamworth Phone: 0439 581 672 Email: steven.simpfendorfer@dpi.nsw.gov.au

Western Australian Contact: Mr Geoff Thomas Plant Pathologist Department of Agriculture and Food, Western Australia South Perth Phone: 08 9368 3262 Email: geoff.j.thomas@agric.wa.gov.au

Queensland Contact: Mr Greg Platz Principal Pathologist Agri-Science Queensland Department of Agriculture and Fisheries, Warwick, QLD Phone: 07 4660 3633 Email: greg.platz@daf.qld.gov.au Professor Stephen Neate Professor, Crop Pathology Centre for Crop Health University of Southern QLD Toowoomba, QLD Phone: 07 4631 1240 Email: stephen.neate@usq.edu.au

GRDC Contact: Dr Ken Young General Manager Crop Protection Grains Research and Development Corporation (GRDC) PO Box 5367, Kingston, ACT, 2604 Australia Phone: 02 6166 4500 Email: ken.young@grdc.com.au

Useful links

Plant Health Australia - Factsheets www.planthealthaustralia.com.au/nationalprograms/grains-farm-biosecurity-program/grainspest-fact-sheets/

Rust Bust www.rustbust.com.au

> Barley Stripe Rust > Wheat stem rust, pathotype Ug99

GRDC Factsheets

Plant Health Australia - Grains Farm Biosecurity Program

www.grdc.com.au/Resources/Factsheets > > > > >

Cereal Fungicides Fungicide Timing Adult Plant Resistance Green Bridge Stem rust of wheat

www.planthealthaustralia.com.au/nationalprograms/grains-farm-biosecurity-program/

University of Sydney â&#x20AC;&#x201C; Australian Cereal Rust Control Program

National Variety Trials

www.sydney.edu.au/agriculture/plant_breeding_ institute/cereal_rust/

www.nvtonline.com.au

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