East: Mild winter results in high burden of crop disease

A borrowed motto for 2016: “When the going gets tough the tough get going!”

Over winter we have heard and spoken about all that is gloomy in agronomy; low crop prices, lost actives, pesticide resistance, building disease and pest pressure, not to mention those expletive inducing buffer zones! So another “winter” has passed (I didn’t need my thermals!) and now is time for field walking, to complete nitrogen and sulphur plans and to firm up the spring spray strategies.

At the time of writing fields are wet and the mild winter has left a legacy of susceptible crops burdened with high levels of disease. However, as conditions become drier, crops will soon perk up and respond to increasing day length. Robust pre-emergence herbicide programmes have worked relatively well, but any unchecked grassweeds have continued to grow in mild conditions and may be difficult to control with spring contact sprays.

Growers will be eager to start to chip away at the heavy spring workload once field conditions improve. Remember that good seed-beds are often more important than calendar date, so it may be several days or even weeks before some fields are dry enough for action. Nitrogen and sulphur plans are in place and winter rapeseed, later-drilled wheat (mid-October onwards) and winter barleys will receive their first fertiliser dose later in February when crops are ready to utilise these nutrients.

There are a few outstanding spray jobs to be completed as soon as field conditions allow. Early November was exceptionally mild and with this in mind, check all cereal crops were protected against barley yellow dwarf virus infection (by seed treatment and or foliar sprays) into mid-November. Although aphid migration had ceased by December, it was also exceptionally mild, allowing any established colonies in crops to develop (albeit in small numbers). As a precaution it could be worth controlling any overwintered populations in these crops before colonies expand and spread the virus in early spring.

Manganese symptoms are also showing affected crops should be treated with robust doses when conditions allow.

On rapeseed the label “cut off” date for Kerb (propyzamide) is the end of January and for Crawler (carbetamide) it is the end of February.

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