Monday, June 24, 2019

Emergency authorisation granted for sugar beet aphicide

June 3, 2019 by  
Filed under Crops

120-day emergency authorisation has been granted for the use of Biscaya (thiacloprid) to prevent virus yellows infection by controlling peach–potato aphids in sugar beet.

The emergency authorisation was applied for by British Sugar and the NFU. It permits up to two treatments of Biscaya per crop at a maximum individual dose of 0.4 litres/ha until 15 August. Treatments should be driven by the presence of aphids in crops and treatment thresholds.

The extent of the yellow water-pan trap network – set up to monitor aphid numbers – has been doubled this year to provide growers with advance warning of any potential problem in sugar beet crops, says BBRO head of science Mark Stevens.

“There are 60 evenly distributed throughout the four factory areas and catches will feed into an interactive map where sugar beet growers can view their three closest water pans simply by entering the farm post code.”

Crops should be monitored as soon as the network shows that winged aphids are being caught in the locality, says Dr Stevens.

Based on an assessment of 10 plants per field, the treatment threshold up to 12 true leaves is an average of one green wingless aphid per four plants. The threshold rises to one aphid per plant from 12 to 16 leaves, as mature plant resistance comes in.

Swift action

Assessments should be recorded in accordance with integrated pest management (IPM) guidelines.

Previously seed treatments were at work when winged aphids entered crops. But foliar spraying means there is often a time lag between threshold identification and product application. Growers should move quickly to control aphids when the threshold is reached.

“If you’re two days short of a herbicide timing, don’t wait for the opportunity to tank-mix. Get the insecticide on immediately. We don’t want secondary spread of virus within the crop, especially at early growth stages when virus yellows’ impact on yield is at its greatest.”

Resistance management is important too, adds Dr Stevens. “The emergency authorisation states that Biscaya should be used in alternation with insecticides of a different mode of action. Ideally we would want no insecticide applications but we may need three.”

To comply with the emergency authorisation and IRAC resistance management guidelines, Biscaya should be used first. If further applications are needed, Dr Stevens says growers should follow with Teppeki (flonicamid) then switch back to Biscaya.

In addition to yellow water-pan catches, the BBRO interactive map will show the results of BBRO testing for the yellowing viruses carried by these aphids.

The map is at www.bbro.co.uk/on-farm/aphid-survey-map/

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