Aphid Alert...Mild weather could see aphid risk to cereal crops
In the middle of November and aphids are still being found in cereal crops across the west and south of the country. Mainly Bird cherry-oat aphid, which is one of the main vectors of BYDV.
At Syngenta’s Innovation Centre in Shropshire, a Sencrop weather station has been set up, this gives real time data and has recorded average daily temperatures above 3oC from the date of crop emergence (5 October 2018) until now. There have been 25 days where the temperatures were above 3oC, this increases the aphid migration risk, especially in crops that have not had Deter seed treatment. Aphid traps were sampled on 9, 18, 24 & 30 October 2018 and each recorded fairly high numbers of aphids present.
Insecticide seed treatments will have activity for up to 8 weeks, a follow-up spray will then be required if populations remain high. HALLMARK ZEON is the most persistent pyrethroid available. Applying 50 mls/ha will reduce the need for several follow-up sprays and help reduce the risk of resistance build-up.
At the Shropshire Innovation Centre T-Sum 170 was used to help apply HALLMARK ZEON at the correct timing to provide the best protection against BYDV infection (see below). After an insecticide application T-Sum 170 will be reset to 0 and the tracking of cumulative temperatures above 3oC will begin again.
Areas in the north still need to vigilant as they have had high levels of aphids caught in the Rothamsted insect traps.