AUTUMN WEED CONTROL

Grass Weed Identification

Canary Grass

There are two significant types of canary grass in Ireland, the most common of which is lesser canary grass. The other, less common species is known as awned canary grass. Lesser canary grass is extremely competitive and produces a huge number of seed per head, making seed return an issue. Ripe seeds are dark in colour and quite small (~2mm).

Lesser canary grass inflorescence. This weed grows out over the crop canopy when fully mature. Resistance to certain ACCase inhibiting herbicides is suspected, but not yet confirmed in Ireland. Lesser canary grass can quickly become a serious issue on the farm if not controlled correctly. Serious yield losses can occur if the population grows unabated. Stale seed beds have limited effectiveness for this weed as it is naturally spring germinating. Remember that for weeds with large seed return like canary grass and black grass, you need 98% control to keep the population at the same level.

Significant population of lesser canary grass growing in a field of spring wheat.

Wild Oats

Wild oats are one of the most common grass weeds in Ireland, causing significant yield losses each year when uncontrolled. Long term studies suggest that wild oats can remain viable in the soil for more than 20 years, so control in the field is essential. Like canary grass, certain populations of wild oats are thought to be herbicide resistant in Ireland, but this has not been confirmed. Irish certified seed has ZERO tolerance for wild oats. Wild oats in Ireland are typically divided into common wild oats (Avena fatua) and the less common winter wild oats (Avena ludoviciana). In the UK, herbicide resistance is more common in the winter wild oat. The two varieties can be identified from one another by looking at the awns on the seeds in the spikelets. In the case of the common wild oat, the three seeds in the spikelet have awns, whereas in the winter variety, the 3rd seed in the spikelet will lack an awn. Furthermore when the seeds ripen, common wild oat seeds will part after shedding whereas winter wild oat seeds tend to stick together (this observation only applies to shed seed as unripe seeds will tend to stick together in both cases).

Left-Common wild oat, note the awn on the 3rd seed in the spikelet. Right- Winter wild oat, 3rd seed has no awn and there may be a small 4th seed emerging, as per the picture. When identifying wild oats at the vegetative stage in an emerging cereal crop. Look for two features: The wild oat has no auricle whereas wheat and barley developed auricles. Also, wild oat leaves tend to twist anti-clockwise when viewed from above, with barley and wheat leaves twisting clockwise. Bear in mind that identification at the vegetative stage is not extremely reliable.

Left to right- Wild oat, wheat and barley auricles. Note hairy auricles of wheat, and curled auricles of barley. Worth notingcommercial oats also have no auricles.

Grass Weed Identification

Black Grass

Black grass is the most commercially important grass weed in the UK and much of mainland Europe. This is due to the significant levels of herbicide resistance seen with this weed. There are a number of confirmed populations of this weed in Ireland that need to be monitored closely. Importing seed, machinery or bales from the UK carries with it significant risk of black grass infestation so extreme caution is advised with any of these practices. Like the bromes, black grass thrives in min-till and no-till operations, but populations can be reduced with smart ploughing rotations and spring cropping, allowing for the use of a stale seed bed approach. It is extremely important to note that if a grower has this weed, and a certain herbicide is not proving effective against it, do not use the same herbicide mode of action on the population again, as this effectively selects the most resistant individuals from the population. If a grower suspects herbicide resistance, send seed samples of the weed to be tested by Teagasc (for free). It is worth noting that many British population of black grass are resistant to multiple herbicides so care is advised when forming a management strategy for this weed. Black grass is easily identifiable, it has long, narrow inflorescences that can be green or plum coloured. It grows upright and can tower over the crop canopy.

Black grass growing in a pot in Teagasc Oak Park, zoomed in to show inflorescences. Plants produce a large number of seed heads each of which produce, on average, 100 seeds. This makes minimising seed return priority number one when controlling black grass. If you find populations of black grass in the field, spotspray with glyphosate as soon as possible before seeds ripens and become viable. Exercise extreme vigilance with fields containing black grass. Care must be taken to clean machinery after harvesting affected fields to minimise the spread of seed.

Management • Irish certified seed has ZERO tolerance for black grass. If importing seed from the UK, ask for a weed certificate. • Stale seed bed approach works well as black grass germinates in the autumn. • Later sowing date allows glyphosate application to cultivated stubble. • Spring cropping facilitates more than one stale seed bed. • Spot-spray small populations before they get a chance to produce viable seed. • Use a well-thought out plough rotation to minimise seed return (burying seed destroys 75% of seed per year), be careful not to plough up old seeds.

• Use competitive crop varieties and a smart rotation, allowing the use of different herbicide chemistries. Herbicide Resistance • 98% of UK black grass is resistant to at least one herbicide mode of action, and 46% have multiple resistance due to herbicide metabolism abilities (stats courtesy of Cook et al., 2014) • If resistance is suspected, send ripe seed samples to be tested in Oak Park. • Do not use the same herbicide mode of action on the population repeatedly. • Do not use reduced doses of herbicides as this contributes to the evolution of multiple herbicide resistance. • Exercise extreme care with machinery that has worked in a field containing black grass to avoid the spread of resistant seed. Protocol for reducing blackgrass seed infestation on farm • Desiccate crop before blackgrass produces seed in order to prevent seed return. Clean down tractor and sprayer before leaving the field. • Hand rogue plants • Harvest the crop last – to avoid contaminating other fields • Turn up fan on the combine as high as possible to blow out as much seed as possible. • Chop the straw; do not bale – to avoid contaminating balers and spreading seed in straw. • Clean down the combine thoroughly before leaving the field including concave, drums, rotors, straw walkers, grain return pans, intake, header, straw chopper, axels, all covers, all flat surfaces etc. Run the combine before leaving the field.

AUTUMN HERBICIDE OPTIONS WINTER WHEAT

PRODUCT

FIREBIRD / SHARP TURBO

(Pre-em option or early post-em option) Cleared up to GS 23

ACTIVE INGREDIENT RATE WEEDS CONTROLLED

400 g/l Flufenacet 200 g/l Diflufenican 0.3 L/ha AMG, Rough stalked MG, Cleavers, Common chickweed, Common speedwell, Ivy-leaved-speedwell, Cranesbill, Forget-me-not, Field pansy, Groundsel, Dead nettle, Mayweed, Shepard’s purse, Volunteer OSR

FIREBIRD MET (contact and residual) Pre and early post emergence option, cleared up to GS 25 or the end of November

FLIGHT (Pre-em option or early post-em option) Cleared up to GS 30

330 g/l PDM 7.5 g/l Picolinafen 3.0 - 4.0 L/ha AMG, Rough stalked MG, Common chickweed, Fumitory, Poppy, Corn marigold, Common speedwell, Ivy-leavedspeedwell, Knotgrass, Cranesbill, Field pansy, Dead nettle, Shepard’s purse, Volunteer OSR

240 g/l Flufenacet 90 g/l Diflufenican 70 g/l Metribuzin 0.5 -1.0 L/ha AMG, Italian Rye Grass, Common chickweed, Common speedwell, Charlock, Poppy, Cranesbill, Forget-me-not, Field pansy, Groundsel, Dead nettle, Mayweed, Shepard’s purse, Volunteer OSR

STOMP AQUA

(Pre-em option or early post-em option) Cleared up to GS 30 445 g/l PDM 2.5 L/ha Max dose is 2.9 L/ha AMG,Common chickweed, Poppy, Common speedwell, Ivy-leaved-speedwell, Field pansy, Dead nettle, Knotgrass, Corn marigold, Volunteer OSR

DEFY / ROXY

(Peri-em option or early post-em option) Cleared up to GS 21 800 g/l Prosulfocarb 2.0 L/ha AMG, Rough stalked MG, Cleavers, Common chickweed, Common speedwell, Ivy-leaved-speedwell, Field pansy (moderate), Dead nettle

DIFLANIL 500

(Post-em option but can also be mixed with Firebird pre-em) Cleared up to GS 31 500 g/l Diflufenican 0.25 L/ha Common chickweed, Common speedwell, Ivy-leavedspeedwell, Field pansy, Dead nettle, Groundsel, Vol OSR, Radish, Nipplewort

TOWER

(Pre-em option and early post-em option) For best results, Tower should be used pre-em. Cleared up to GS 30 250 g/l Chlortoluron 300 g/l PDM 40 g/l Diflufenican 2.0 L/ha AMG, Loose Silky Bent, Cleavers, Charlock, Common chickweed, Fumitory, Poppy, Common speedwell, Ivyleaved-speedwell, Cranesbill, Field pansy, Dead nettle, Shepard’s purse, Volunteer OSR, Runch, Mayweed, Forget-me-not

COMMENT

Firebird @ 0.3 L/ha delivers 120 g/ha Flufenacet + 60 g/ha Diflufenican. Two applications per crop permitted. For best results, product should be applied pre-em. A good option at pre-em where Bromes are becoming an issue. Should be used in conjunction with Alister Flex where Brome and Blackgrass is particularly bad. Can also be used in conjunction with DFF (0.1 - 0.2 L/ha) to improve control of Vol OSR and Chickweed. Poor on Wild Oats, Fumitory and Poppy. By using in an integrated approach with Alister Flex, good Wild Oat control will be achieved.

Firebird Met @ 1.0 L/ha delivers 240 g/ha Flufenacet + 90 g/ha Diflufenican + 70 g/ha Metribuzin. Post emergence up to GS 25 (early postem). Strong option on Bromes and Blackgrass. Early post emergence product which can be applied with the aphicide timing. Inclusion of Metribuzin to give increased contact activity on grass and BLW weeds. High rate of Flufenacet will improve residual control on grasses. Better on Cleavers, Fumitory and Poppy than Firebird . Will not control Wild Oats as a stand alone product.

Flight @ 4.0 L/ha delivers 1,320 g/ha PDM + 30 g/ha Picolinafen. By reducing the rate from 4.0 L/ha, control of certain weeds will be compromised. A good option where a farmer wants to go pre-em and Broadway Star is planned for use in the spring. A good option on farms where Poppy and Marigold is an issue. For best results on AMG, it is advisable to go pre-emergence, especially with IPU being no longer available. Use with DFF @ 0.1 - 0.2 L/ha if targeting Vol OSR. Flight is poor on Cleavers (pre-em), Groundsel and Mayweed. Contains PDM so will stain sprayers. This is an issue with some growers.

Stomp Aqua @ 2.5 L/ha delivers 1,112 g/ha PDM. Can be used as a method of controlling AMG in Winter Wheat if Broadway Star is planned as the main herbicide for the Spring. Can be used with DFF pre-em to increase control of Vol OSR or as a method of beefing up other products like Tower or Pontos. For best results, product should be applied pre-em. Will not control Wild Oats. Reasonable on Bromes and grass weeds when used as part of a stacked programme, e.g. with Broadway Star or Alister Flex in the spring. The same staining issues that exist with Flight, does not exist with Stomp Aqua due to a superior formulation.

Defy @ 2.0 L/ha delivers 1600 g/ha Prosulfocarb. Syngenta recommend to use product in conjunction with DFF @ 0.1 l/ha. DFF will greatly improve the performance on Vol OSR and Chickweed. Excellent product on Cleavers. For best results, use Defy at pre-em. Less scorch pressure attached to Wheat as there is to Barley. Do not use product peri-em. Defy needs to be used pre-em to control Groundsel. Poor control of Fumitory and Mayweed. Will not control Wild Oats.

Broad leaf weed control only. Will not control Grass weeds. Ideal tank mix partner with Defy. Mixture of Stride DFF + Diflanil 400 to an overall dose of 0.4 L/ha DFF will increase control of cleavers. Can be used pre-em with Firebird. At modest rates DFF is poor on Cleavers. Very poor on Fumitory and Poppy. Will not control Wild Oats.

Will not achieve any form of control of Wild Oats or Bromes on its own. Do not drop rate below 2.0 L/ha. Stomp Aqua can be included at pre-em to increase rate of PDM which will increase control of grass weeds if known grass weed pressures are high. In order to achieve maximum control of the weed spectrum, product should be used pre-em. By delaying application until early post-em, control of Fumitory and Poppy will reduce. A good early post-em option since the removal of IPU from the market place. Include DFF @ 0.1 - 0.2 L/ha at periem/early post-em to improve control of Charlock and Vol OSR. It Contains PDM but staining levels are at a much reduced rate compared to alternative PDM products like Flight. Poor on Groundsel. Can be used comfortably at post-em on Wheat and will achieve good control of AMG. One should consider mixing Thor with Tower to improve control of Vol Beans in the late autumn.

AUTUMN HERBICIDE OPTIONS WINTER WHEAT

PRODUCT

ALISTER FLEX (Post-em option for winter wheat only) Cleared up to GS 29

PACIFICA PLUS

(Post-em option for winter wheat only) Cleared from Feb 1st to GS 39 30 g/kg Mesosulfuron 10 g/kg Iodosulfuron 50 g/kg Amidosulfuron

500 g/ha (pack/5ha)

AMG, Rough stalked MG, Italian RG, Perennial RG, Wild Oats, Blackgrass, Sterile Brome, Great Brome, Rye Brome, Cleavers, Common Chickweed, Mayweed, Charlock, VolOSR

ACTIVE INGREDIENT RATE WEEDS CONTROLLED

120 g/l Diflufenican 9 g/l Mesosulfuron 7.5 g/l Iodosulfuron 1.0 L/ha AMG,Loose Silky Bent, Rough stalked MG, Fumitory, Poppy, Dead nettle, Groundsel, Mustard, Pansy White Runch/ Wild Radish, Forget-me-not, Common Chickweed,vol- OSR, Charlock, Shepherd's Purse, Speedwells, Mayweed

MONOLITH (Post-em option for winter wheat) Cleared from Feb 1st and GS 21 - 32

BROADWAY STAR

(Post-em option for winter wheat only) Cleared from GS 11 - 32 45 g/kg Mesosulfuron 67.5 g/kg Propoxy-carbazone

7.1 % Pyroxsulam 7.1 % Cloquintocet 1.4 % Florasulam 0.33 kg/ha Increased control over Blacklgrass compared to Pacifica or Alister.Will also control Wild Oats, Rye-Grasses, Sterile Brome, Rye Brome, Loose silky-bent, Common Chickweed and Mayweed

265 g/ha (pack/4ha)

Bromes, Wild Oats, Bindweed, Cleavers, Charlock, Speedwell, Chickweed, Marigold, Creeping Thistle, Pansy, Groundsel, Knotgrass, Mayweed, Poppy, Vol Beans, Vol OSR,

COMMENT

Excellent post-em option on Winter Wheat. This will be a very popular approach going forward this season. Alister Flex will also control Wild Oats. Very good product on Grass weeds and Bromes. Use early post-em in the autumn to achieve good Grass weed and Brome control. If targeting Blackgrass, Alister Flex should be used in sequence post-em following a pre-em application of either Firebird. New formulation of Alister Flex has a wider weed spectrum. Has a tendency to be poor on cleavers so follow up herbicide may be required.

Excellent post-em option on Winter Wheat. This will also be a very popular approach going forward this season. Pacifica will also control Wild Oats. Very good product on Grass weeds and Bromes. Excellent post-em option after March 1st in order to achieve excellent Grass Weed and Brome control. If targeting Blackgrass, Pacifica should be used in sequence post-em following a pre-em application of either Firebird or Vigon. Bio-Power should still be included to maintain product efficacy. Can be used as a mix with Cameo Max to broaden weed spectrum such as Fumitory, Vol Beans etc.

Predominantly a grassweed herbicide with a narrow range in terms of broad leaf weeds. Will control wild Oats. Can be used in sequence post-em following a pre-em application of Firebird. Monolith @ 0.33 kg/ha delivers 12 g/ha Meso + 22.5 g/ha Propoxy. Bio-Power should still be included to maintain product efficacy. Can be used as a mix with Zypar, Thor or Cameo Max to broaden weed spectrum such as Fumitory, Vol Beans etc. Do not mix with PGR's. Stronger option on Bromes and Blackgrass than either Pacifica Plus or Alister Flex.

Will not control AMG so autumn application of Defy or PDM will be required. Reducing dose rate will compromise weed spectrum greatly. Excellent product on Bromes and Grass Weeds. Wild control Wild Oats. Excellent spectrum on Broad leaf weeds. This will be a popular product for spring use on Winter Wheat. The addition of an adjuvant such as Torpedo is recommended to maintain product efficacy.

AUTUMN HERBICIDE OPTIONS IMAGE TO BE CHANGED

WINTER BARLEY

PRODUCT

FIREBIRD / SHARP TURBO (Pre-em option or early post-em option) Cleared up to GS 24

FIREBIRD MET (CONTACT AND RESIDUAL)

Pre and early post emergence option, cleared up to GS 25 or the end of November

ACTIVE INGREDIENT RATE WEEDS CONTROLLED

400 g/l Flufenacet 200 g/l Diflufenican 0.3 L/ha AMG, Rough stalked MG, Cleavers, Common chickweed, Common speedwell, Ivy-leaved-speedwell, Cranesbill, Forget-me-not, Field pansy, Groundsel, Dead nettle, Mayweed, Shepard’s purse, Volunteer OSR

240 g/l Flufenacet 90 g/l Diflufenican 70 g/l Metribuzin 0.5 -1.0 L/ha AMG, Italian Rye Grass, Common chickweed, Common speedwell, Charlock, Poppy, Cranesbill, Forget-me-not, Field pansy, Groundsel, Dead nettle, Mayweed, Shepard’s purse, Volunteer OSR

FLIGHT (Pre-em option or early post-em option) Cleared up to GS 30

330 g/l PDM 7.5 g/l Picolinafen 3.0 - 4.0 L/ha AMG, Rough stalked MG, Common chickweed, Fumitory, Poppy, Corn marigold, Common speedwell, Ivy-leavedspeedwell, Knotgrass, Cranesbill, Field pansy, Dead nettle, Shepard’s purse, Volunteer OSR

DEFY / ROXY

(Pre-em option or early post-em option) Cleared up to GS 21 800 g/l Prosulfocarb 2.0 L/ha AMG, Rough stalked MG, Cleavers, Common chickweed, Common speedwell, Ivy-leaved-speedwell, Field pansy (moderate), Dead nettle

DIFLANIL 500

(Post-em option but can also be mixed with Firebird pre-em) Cleared up to GS 31 500 g/l Diflufenican 0.25 L/ha Common chickweed, Common speedwell, Ivy-leavedspeedwell, Field pansy, Dead nettle, Groundsel, Vol OSR, Radish, Nipplewort

TOWER

(Pre-em option and early post-em option) For best results, Tower should be used pre-em. Cleared up to GS 30 250 g/l Chlortoluron 300 g/l PDM 40 g/l Diflufenican 2.0 L/ha AMG, Loose Silky Bent, Cleavers, Charlock, Common chickweed, Fumitory, Poppy, Common speedwell, Ivy-leaved-speedwell, Cranesbill, Field pansy, Dead nettle, Shepard’s purse, Volunteer OSR, Runch, Mayweed, Forget-me-not

COMMENT

Firebird @ 0.3 L/ha delivers 120 g/ha Flufenacet + 60 g/ha Diflufenican. Two applications per crop permitted. For best results, product should be applied pre-em. A good option at pre-em where Bromes are becoming an issue. Can also be used in conjunction with DFF (0.1 - 0.2 L/ha) to improve control of Vol OSR and Chickweed. Poor on Wild Oats, Fumitory and Poppy.

Firebird Met @ 1.0 L/ha delivers 240 g/ha Flufenacet + 90 g/ha Diflufenican + 70 g/ha Metribuzin. Post emergence up to GS 25 (early postem). Strong option on Bromes and Blackgrass. Early post emergence product which can be applied with the aphicide timing. Inclusion of Metribuzin to give increased contact activity on grass and BLW weeds. High rate of Flufenacet will improve residual control on grasses. Better on Cleavers, Fumitory and Poppy than Firebird. Will not control Wild Oats as a stand alone product.

Flight @ 4.0 L/ha delivers 1,320 g/ha PDM + 30 g/ha Picolinafen. By reducing the rate from 4.0 L/ha, control of certain weeds will be compromised. A good option where a farmer wants to go post-em. A good option on farms where Poppy and Marigold is an issue. For best results on AMG, it is advisable to go pre-emergence, especially with IPU being no longer available. Use with DFF @ 0.1 - 0.2 L/ha if targeting Vol OSR. Flight is poor on Cleavers (pre-em), Groundsel and Mayweed. Contains PDM so will stain sprayers. This is an issue with some growers.

Defy @ 2.0 L/ha delivers 1600 g/ha Prosulfocarb. Syngenta recommend to use product in conjunction with DFF @ 0.1 l/ha. DFF will greatly improve the performance on Vol OSR and Chickweed. Excellent product on Cleavers. For best results, use Defy at pre-em. Has a tendency to scorch Winter Barley when used post-em but crop will recover. Do not use product peri-em. Defy needs to be used pre-em to control Groundsel. Poor control of Fumitory and Mayweed. Will not control Wild Oats.

Broad leaf weed control only. Will not control Grass weeds. Ideal tank mix partner product. Mixture of Stride DFF + Diflanil 400 to an overall dose of 0.4 L/ha DFF will achieve good control of cleavers. Can be used pre-em with Firebird. Poor on Cleavers, Fumitory and Poppy. Will not control Wild Oats.

Will not achieve any form of control of Wild Oats or Bromes on its own. Do not drop rate below 2.0 L/ha. Stomp Aqua can be included at pre-em to increase rate of PDM to increase control of grass weeds if known presures are to be high. In order to achieve maximum control of the weed spectrum, product should be used pre - em. By delaying application until early post - em, control of Fumitory and Poppy will reduce. A good early post-em option since the removal of IPU from the market place. Include DFF @ 0.1 - 0.2 L/ha at peri- em to improve control of Charlock and Vol OSR. It Contains PDM but staining levels are at a much reduced rate compared to alternative PDM products like Flight. Poor on Groundsel. One should consider mixing Thor with Tower to improve control of Vol Beans in the late autumn.

WINTER OATS

PRODUCT ACTIVE INGREDIENT RATE WEEDS CONTROLLED

HURRICANE OR DIFLANIL 500

(Post-emergence option but can also be mixed with Firebird Pre-emergence) Cleared up to GS 31 500 g/l Diflufenican 0.25 L/ha Common chickweed, Common speedwell, Ivy-leavedspeedwell, Field pansey, Dead nettle, Groundsel, Vol OSR, Radish, Nipplewort

COMMENT

Broad leaf weed control only. Will not control Grassweeds. Good product on Winter Oats. Mixture of Stride DFF + Hurricane can bring overall dose to 0.4 L/ha DFF. This will help in the control of Cleavers. However, at low rates poor on Cleavers, Fumitory and Poppy.

Written by Barry Purcell

The Driving Force to Fulfilling Yield Potential

Soil health is one of the key components to successful crop production. The Irish farming community has placed a greater focus on the health of our soils in recent times, which is leading to a positive impact on the environmental and economic sustainability of farming systems. Crop rotations and cover cropping have become an integral component of management practices on tillage soils. This year we have seen the welcome addition of the straw chopping scheme, which again will improve the structure and functionality of our soils. The autumn is often a good time for reflection, to look back on the year gone by and assess the decisions made and their outcome on the final yield at harvest. It is a great opportunity to break the year down, analyse inputs applied and identify where improvements can be made. Continuous tillage soils have been degraded over the years, by harvesting high yields of grain and straw from them, however, in most cases, very little organic matter has been applied back into the soil. With some of the country’s best soils currently used in tillage practices, it is imperative that steps are taken to ensure these soils maintain their high fertility. Straw Chopping: This measure has seen large uptake in its pilot year, particularly with crops that have high a high carbon value such as oats and oilseed rape. This process returns some valuable P and K back into the soil, which will lessen the requirement for chemically applied nutrients in the following crop.

P and K values for a range of crop types based on crop yield (t/ha)

P and K off takes in cereal crops (kg/ha) per tonne of grain yield

CROP TYPE CROP YIELD (t/ha) P (kg/ha) K (kg/ha) SPRING BARLEY

7.5 3 50

WINTER BARLEY

10 4 51

WINTER WHEAT

10 4 56

WINTER OATS

WOSR

9.0

5.0 3.5

2.2 93

25

VALUE (€/ha)

45

50

50

75

25

t/ha ÷ 2.471 = t/ac; kg/ha x 0.8 = units/ac. Values rounded to the nearest €5/ha. P - €2.31/kg and K - €0.78/kg. Source Teagsc.

Adjusting P & K input: Harvest yields have been positive this season, which in turn leads to high nutrient offtake from the soil. This nutrient offtake, needs to be resupplied to the next growing crop to ensure another successful growing year.

CROP TYPE

WINTER WHEAT / BARLEY

SPRING WHEAT / BARLEY

OATS STRAW REMOVED

P

3.8

3.8

3.8

K

9.8

11.4

14.4

STRAW NOT REMOVED

P

3.4

3.4

3.4

K

4.7

4.7

4.7

Tackling Take-All

With the 2022 harvest wrapped up and we take a look back at the year gone by, there was a lot of success stories with high yields achieved across the country. Winter wheat and spring barley crops in general were excellent. However, winter barley showed huge variation in yield, which left many growers disappointed after all their hard work throughout the season. This poses the question as to why did winter barley disappoint while other cereal crops done very well. Take-all may be some of the reason for that yield variation.

What is Take-All

Take- all is a soil borne fungus (Gaeumannomyces tritici) that affects the roots of the growing cereal crop. Inoculum in the soil from the previous crop can infect newly sown autumn seedlings. There is two sources of infection to take-all: Primary infection: This occurs in the autumn when inoculum has built up in the soil. This affects newly sowing cereal seedlings. Secondary infection: This occurs in the spring/summer, especially in situations of high primary infection. Infected roots spread the disease to the developing crown roots. This is more prevalent in warm, moist soils. The pathogen is active when soil temperatures are above 10-12 degrees. As the growing season progresses, roots infected with take-all will start to shut down and this will affect the plants ability to absorb nutrients and moisture from the soil. When take-all is severe, the plants root system succumbs to the disease and this will result in the premature ripening of a crop. This results in whiteheads across a field, often in patches, with those ears having poor shrivelled grain and in some cases no grain at all.

Cultural control methods to prevent infection:

Rotational strategies

Rotation is the best way to reduce the risk of Take-All on your farm. The more diverse rotation the better with different break crops and a longer cycle between cereals. Break crops include OSR, oats, beans, peas, beet, shortterm ley, vegetable crop.

Cultivations

Fungal growth in the soil can be restricted in firm seedbeds. It is important to try and roll fields after sowing to try consolidate the seedbed. However, on heavy soils or soils sown prior to heavy rain, can lead to compaction. Compaction can restrict root growth and increase the severity of the disease on the plants root system. Ploughing will bury most of the inoculum, which will be in the top 100mm after harvest. This gives the plant time to establish with reduced levels of early infection. Minimum tillage can leave highly infected soil near the surface and in the root zone of the newly sown crop.

Volunteer cereals

Volunteer cereals and some grass weeds such as scutch/ couch grass and some bromes can carry the take-all infection from one crop to another. It is important to spray off fields with glyphosate to remove volunteer cereals and other weeds.

Drilling date

The level of take-all inoculum in the soil falls rapidly after harvest. Delaying the drilling date is a sensible approach to reducing the risk of infection. The weather conditions before, during and after sowing control the level of risk to the crop. As the pathogen is active when soil temperatures are above 10–12˚C, ideally delay sowing date until soil temperatures are below this. Sowing first cereals before second/third cereals will also help reduce the severity of the infection.

Seed rate

The seed rate and the quality of the seed is important to mitigate the risk of take-all infection. Using certified seed and reducing seed rate in vulnerable fields can reduce the take-all risk. The higher the seeding rate, the higher the root density which will lead to more primary and secondary infection.

Nitrogen application

Applying nitrogen earlier to second/third cereal crops can reduce the impact of take-all on that crop. As take-all affects roots it is important to apply nutrients to the crop before secondary infection takes place. Crop uptake of nutrients will be restricted and inefficient at a later stage.

Phosphorus

As phosphorus has an impact on root growth, rectifying phosphorus deficiencies will enable the crop to survive more efficiently in take-all risk slots.

Chemical control methods

Foliar fungicides have no control over Take-All leaving the only chemical control available to seed treatments. It is advised to use Latitude dressed seed where there is a potential Take-All risk.