Seven key steps to supercharging second wheat

Take just seven key steps and a second wheat crop could give returns to rival that of a good first wheat crop, according to recent figures from Masstock.

Research carried out by the firm for its Best of British Wheat campaign suggests these seven steps can increase second wheat yields by up to 3.5t/ha and profits by £372/ha, says technical director Clare Bend. “These figures have each been individually achieved in trials and this graphic demonstrates how much, in theory, each step could contribute.”

• Decision 1 – Choose the right variety

Growers should refer to the HGCA Recommended List and choose a variety that performs well in the second wheat position

Actual yield when grown as a second wheat and the yield penalty when grown in the second wheat position should both be considered

These criteria put Ketchum, Cocoon, JB Diego, Duxford, Grafton, Battalion, Gladiator and Humber in the top spot

• Decision 2 – Drilling date and seed rate

Do not drill too early and never drill prior to October unless seed is dressed

The higher the seed-rate the more take-all white heads you get because plants are closer together and take-all can move between plants more easily

However, yields do suffer if seed-rates fall too low and growers should discuss suitable rates with their agronomists

Masstock trials with seed rates of 200 seeds/sq m and 350 seeds/sq m showed significantly higher take-all infection at the higher rate

• Decision 3 – Use a suitable seed dressing

Seed dressings are crucial for preventing take-all infection, but growers need to assess disease risk before choosing a product

Some of the risk elements to consider are cropping history, soil type and pH, drilling date and varietal tolerance to take-all

If take-all risk is high and there is minimal risk from rusts and septoria growers should use a single-purpose dressing with Latitude (silthiofam)

Where take-all risk is medium, but rust and septoria risk is high, a HR fluquinconazole seed dressing such as Jockey is most appropriate

If take-all risk is low and rust and septoria risk is high it is best to opt for a LR fluquinconazole product such as Epona

For low take-all rust and septoria risk, a single purpose dressing such as Redigo Deter (clothianidin + prothioconazole) should suffice

• Decision 4 – Apply nitrogen early

Continuous supply of nitrogen helps crops overcome take-all infection and second wheat crops should receive 40% of their total nitrogen dose in February or early March. However, field drainage risk, crop growth stage and rooting also need to be considered

Autumn applications can also be beneficial, but growers need to be prepared to justify this to the Environment Agency

Due to their lower nitrogen use efficiency, more nitrogen is required per tonne of yield compared with a first wheat

Ammonium sulphate is the best nitrogen source for reducing risk of take-all infection and is a useful option in high-risk situations. Evidence suggests nitrogen in the ammonium form causes reduced pH in the rhizosphere, which reduces disease severity and improves manganese availability

• Decision 5 – Achieve good P&K index

Growers should achieve a phosphate index of 2 before the first wheat crop is established. Phosphate-deficient soils favour the take-all fungus and if wheat is grown after a break crop in a phosphate deficient soil, inocculum builds up quickly

Foliar phosphate applications such as Nutriphite PGA will aid root development and reduce the effects of the disease

• Decision 6 – Foliar nutrition

Foliar manganese and copper treatments are key tools for reducing the take-all threat. Manganese is particularly important as it delays disease development, restricts the size of root lesions and boosts root development

Experiments have shown that the take-all fungus catalyses the oxidation plant-available nitrogen to the unavailable form meaning soils with acceptable manganese levels may still need to be treated

Manganese seed dressings and soil-applied treatments can significantly reduce take all, and foliar treatments are useful for keeping the crop healthy

Copper helps improve plants’ natural immunity to the take-all fungus

• Decision 7 – T1 fungicide

Strobilurin fungicides can help reduce yield losses from take-all infection if robust doses are used. The fungicide attacks the fungus directly through the soil, so it is best to apply to moist soils before rainfall. Masstock trials suggest yield benefits of 0.2-0.4t/ha where a strobilurin is added at T1

New SDHI chemistry has also given positive results in the firm’s second wheat trials by improving drought tolerance and extending the persistence of green leaf

Bixafen was the most consistent active ingredient with T1 applications significantly improving tiller retention. This action is particularly valuable where water and/or nutrient uptake is compromised by drought or take-all infection.

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