Growers urged not to skip pulse sprays in muggy weather

22 May 1998




Growers urged not to skip pulse sprays in muggy weather

By Andrew Blake

MUGGY weather makes it inappropriate to ease up on pulse spraying, warns Anthony Biddle of the Processors & Growers Research Organisation.

Moist soils, warm, humid weather and plenty of disease inoculum put unsprayed crops at particular risk, he says. Signs are that pests, especially aphids, are also thriving.

Most winter beans have been sprayed with fungicide in the past couple of weeks, says Dr Biddle. "But with disease pressure as it is in most crops a second spray is more or less essential to keep on top of chocolate spot and ascochyta."

Infection is currently mostly low down on plants. But growers should not delay too long because crops are growing fast, he advises. "It will soon be their last chance to get on."

Use of a triazole mixture, giving protection against rust, could be a worthwhile alternative to mbc/ chlorothalonil at this stage, he suggests.

Downy mildew is widespread in spring beans, encouraged by Aprils high humidity legacy. "Susceptible varieties like Victor really need watching." Folio (chlorothalonil + metalaxyl) is the sole appropriate product, he says. "If 25% or more of the plants have mildew on the top three sets of leaves, dont be tempted to cut rates."

Warm weather means bruchid beetles are already showing up in winter crops. That serves as a warning that for premium export quality spring types a deltame-thrin-based spray may also be needed before the first pods are visible and again 10 days later, says Dr Biddle.

Bacterial blight in winter peas, brought on by Easter frosts, has subsided, he reports. "But there is quite a lot of mycosphaerella in the bottom of crops. Once the crop goes down and we get a wet spell it could romp all over the top." A protectant spray before that happens is good advice, he says. The extra early arrival of aphids in winter peas suggests some may have over-wintered. "If you are going through with a fungicide and you can find the proven threshold of one aphid on five plants you should think about using Aphox."

PULSE SPRAYS

&#8226 Plenty of disease inoculum.

&#8226 Unusually early pest activity.

&#8226 Two sprays on winter beans?

&#8226 Downy mildew on spring types.

Pulse spraying, against weeds, diseases and pests could be especially well rewarded this season. Here an anti-wild oat treatment goes onto Progreta peas at Clint Street Farm, High Halstow, Kent. Meanwhile, (left) Philip and Conrad (right) Underwood are pleased with the cleanliness of 22ha of Rafale winter peas at Field Farm Cropwell Butler, Notts after a recent applicaion of Ronilan (vinclozolin), Roger (dimethoate) and manganese.


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