West: Wet weather complicates management decisions

Winter wheat crops are now moving rapidly to flag leaf emergence. Most crops have the tip of leaf 1 visible (GS 37) and a minority in low lying sheltered areas are at GS 39, flag leaf fully unfurled. Septoria is widespread in the base of the crop. At the moment yield forming leaves are clear of disease, however, where leaf 3 spray timings were compromised it is likely that this leaf is now infected and will form a bridge to infect leaf 2.

Flag leaves sprays must be sufficiently strong enough to protect leaf 1 and clean up leaf 2. In the current conditions this only means one thing, a strong dose of SDHI and triazole with chlorothalonil where the selected SHDI allows.

On farms where silage making is delayed by the weather there is bound to be a compromise between grass harvesting and wheat spraying. The wet conditions have delayed maize drilling which further complicates matters. In these situations I will be looking to use high doses of strongly curative fungicides based on fluxapyroxad. The mild, wet weather has also led to an upsurge in growth, with wheat plants showing some massive leaves and high above ground biomass. There is a much greater need for late season plant growth regulators (PGRs) this year.

Weeds have flourished in the rain and dissolving clods on heavier land have spawned a flush of polygnums that will need to be taken care of when the flag leaf spray is applied. Be careful with your use of sulfonylurea herbicides because in some cases all legally available applications have been utilised. Easel is an MCPA formulation which can be used in wheat up to GS39 and can be extremely useful. Soil temperatures in Somerset are almost 1C higher than normal, which is no doubt spurring the weeds on as much as the crops.

Oilseed rape is approaching the end of flowering and sclerotinia has been a major concern. Where the first spray has been on for three weeks and flowering is likely to continue for a further two weeks, a second treatment will be applied. If it continues wet then we will have to start thinking about alternaria treatments. Slug populations at the base of rape crops are extraordinarily high and we hope for some dry, settled weather to thin them out.

Winter beans are starting to flower and first fungicides based on cyproconazole plus chlorothalonil are now being applied. Charlock and volunteer oilseed rape have been problematic, but a well-timed bentazone treatment has generally sorted things out. With good seed-beds and adequate moisture, pre-emergence treatments in spring beans are working well. Despite the wetness, sitona weevil has been very active, sometimes necessitating two pyrethoid treatments.

Spring barley is doing its usual sprint through the growth stages and will be soon be ready for a broad-leaved weed spray and fungicide. Volunteer spring barley is plastered in rhynchosporium, but the drilled crop is currently clear. Grassweeds were targeted by pre-emergence treatments including Avadex (tri-allate) in the worst situations, followed by a post-emergence pinoxaden spray.

Spring oats are thriving in the wet and look to be beating spring barley in the race through the growth stages. We like to treat broad-leaved weeds early in this crop to avoid over stressful later mixes with fungicides and PGRs.

NOVEMBER
3

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