With the continuing wet, warm and humid conditions, this season will be a particularly high pressure year for a number of diseases in brassicas, according to John McCulloch of specialist agronomist County Crops.
There are also concerns about controlling these diseases adequately, but without increasing resistance risk.
Advising growers in the North West, McCulloch said that he has seen more Sclerotinia this year than ever before. “I have seen a lot of it in the usual crops such as lettuce, celery, carrots and oilseed rape and also in some more unusual crops such as calabrese.
“These high levels can be put down to this year’s terrible weather and high rainfall, which have encouraged Sclerotinia as well as other wet weather diseases including ring spot (Mycosphaerella brassicola), white blister (Albugo candida) and Botrytis.”
McCulloch advises his growers to adopt an appropriate fungicide programme, but with fungicide resistance and crop safety being top of the agenda. “We need to produce high-quality vegetable brassicas with good visual appeal and this means no blemishes caused by disease,” he said.
McCulloch advises starting the programme early with a fungicide such as Signum. It can be mixed with a triazole as part of a resistance strategy and then followed by other fungicides with different modes of action. It also is a benign product when it comes to crop safety.
“You want to avoid any treatment that could dewax the crop.” he said. “County Crops has nine weather stations that help flag up when disease prevention measures are needed and make sure that we use fungicides only when necessary.”
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