Take-all Control in Winter Wheat: II Agronomy (HGCA Topic Sheet No.50)

Take-all Control in Winter Wheat: II Agronomy

TS No.50
Summer
2001



Action:

  • Consult the NIAB Cereals variety handbook to choose varieties as second (or third) wheats.
  • Sow first wheats first, followed by long-term wheats likely to be in take-all decline. Sow second to fourth wheats last, ideally in mid-October, whether a seed treatment is used or not.
  • Treat earlier-sown higher-risk wheats with Latitude (silthiofam),Jockey (fluquinconazole + prochloraz) or possibly with Baytan (fuberidazole + triadimenol).
  • When using a take-all product, match seed rate to sowing date and seedbed conditions as you would with a standard seed treatment.
  • Apply a large-enough first spring N dose (1/4 to 1/3 of total), whether a standard or take-all seed treatment is used.

Variety and sowing date

Although some varieties are more tolerant of take-all than others, variety choice is less critical when using a seed treatment. Seed treatment will reduce differences in variety performance.

Where take-all risk is high, delayed drilling helps to reduce risk. However, any potential benefit is limited because yields typically decline when crops are sown too late. The optimum drilling period for second and third wheats is usually around mid-October.

ADAS trials have shown that treatment with silthiofam increased yields by a similar amount across a wide range of sowing dates. However, it is important to note that the optimum sowing period remained the same (Figure 1). The seed treatment can offer some sowing date flexibility.Treated crops sown up to two weeks before the optimum timing yielded the same as untreated crops sown at the optimum timing.

Seed rate

ARC trials used 200, 300 and 400 seeds/m2 both with and without seed treatment. Take-all incidence in spring tended to be higher at high seed rates, and margin over input costs higher at lower seed rates. Seed rate did not have an effect on yield and seed treatment did not alter this (Figure 2).

Fuberidazole + triadimenol treatment reduced take-all by somewhat less than did silthiofam in April and June disease assessments. Yield responses, albeit less consistent, were sometimes similar in crops sown in September, but not in October to those from silthiofam. As this  seed treatment is half the cost of silthiofam its use may be attractive in earlier-sown crops.

Nitrogen rate and timing

Crops infected with take-all cannot take up N efficiently. The standard recommendation for wheat crops at risk of take-all has been to apply N earlier than for first wheats to allow the crop to take up the N whilst the root system is less damaged. Where silthiofam was used in ARC trials optimum output was still achieved by applying higher rates of N and a larger proportion early in the spring (Figure 3).

Summary

The launch of two new take-all seed treatments gives farmers the potential for more profit from second and subsequent wheat crops. Most HGCA-funded work to date, as reported in this Topic Sheet, has been on silthiofam only. Direct comparison between the efficacy of the two new take-all seed treatments is therefore not possible. In some trials an older seed treatment, not specifically developed for take-all, was used.

However, it is clear that complete control cannot be achieved simply through the use of a seed treatment. This Topic Sheet builds on no. 49 to cover effects of several agronomic factors which,employed in combination with seed treatment, can help to ensure the best possible control of take-all.

Further information:

John Spink, ADAS
Tel: 01432 820444

Projects 1301, 2443

Stuart Knight, ARC
Tel: 01767 627510

Project Report 255


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The Home-Grown Cereals Authority (HGCA) has provided funding for this project but has not conducted the research or written this report.While the authors have worked on the best information available to them, neither the HGCA nor the authors shall in any event be liable for any loss, damage or injury howsoever suffered directly or indirectly in relation to the report or the research on which it is based.

Reference herein to trade names and proprietary products without stating that they are protected does not imply they may be regarded as unprotected and thus free for general use. No endorsement of named products is intended, nor is any criticism implied of other alternative, but unnamed products.

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