After recent rain, growers are being advised to ensure sugar beet crops are as free from disease as possible and also to consider applying foliar nutrients. This will help recover some of the yield potential likely to have been lost following weeks of hot, dry weather.
Dr Simon Bowen, knowledge exchange and crop progression lead at BBRO, says there was a lot more cercospora seen in sugar beet crops last year compared with previous years. “This could act as a potential reservoir of the disease. It likes humidity and heat. We have had some early reports of it and some confirmed.”
However, before rushing to apply fungicide, it is important not to confuse it with general stress symptoms, says Dr Bowen. “Look for discrete lesions and necrotic areas on leaves. A lot of stress symptoms are at the leaf margins whereas cercospora has regular circular lesions within the leaf. The fungus can develop within 5-10 days of the leaf being infected and lesions are initially pale then turning brown.
“Treat as soon as you see symptoms. Also look out for rust and powdery mildew developing. When it has been very dry and hot there has not been much disease but moisture and humidity triggers sporulation.”
Checking different varieties and different fields for disease is important, particularly with cercospora where there is limited knowledge of which varieties are most susceptible, says Dr Bowen. “Don’t assume because you haven’t seen it in one field it isn’t in another.”
Keeping canopies clean will be important in enabling sugar beet to compensate for some of the yield potential lost because of the dry weather, he says. “On lighter land, crops that went in relatively early fared not too badly. For those that went in later, particularly on lighter land, canopies failed to develop well in the hot weather.
“Those drilled early on more bodied soils have managed to survive reasonably well – canopies were not too compromised. With rain now there is a good chance these crops will pick up and be able to produce yield.”
As well as looking out for disease, applying foliar nutrition may also help crops to recover, says Dr Bowen. “Where crops are growing again, quickly, a well-timed application of trace elements can pick up canopies.”
Yields could be down 10-20 per cent on some drier soils, estimates Dr Bowen.