Warm weather raises BYDV threat to high

Recent mild weather is resulting in reports of large flights of aphids which are rapidly colonising newly emerging winter cereals and infecting them with the yield robbing Barley Yellow Dwarf Virus (BYDV), says agronomist Elle Pace, agronomist in Sussex.

The latest monitoring by AHDB and Rothamsted reports aphid activity is rising, particularly the numbers of bird cherry-oat aphids. In early October numbers rose by 35% to above the 10 year mean, at all but two sites in the UK.

Subsequently there have been reports of a major aphid flight along the south coast, meaning that cereal crops are at high risk.

Elle recommends that crops sown in high risk areas, should use Deter or Redigo Deter for early drilled crops. “This will provide about 6-8 weeks protection when the crop is at its most vulnerable during emergence and establishment.”

“Where seed has not been protected to use an aphicide spray, and don’t delay treatment when warnings are issued.”

“The minute the crop pokes through the ground it is at risk, and as the current threat is so high the advice would be to spray an aphicide onto the crop around the 1 leaf stage, don’t wait for 2 leaves – this should provide about 7 days repellant activity  – that’s providing the aphids show no sign of resistance.”

Generally, after the first application of a pyrethroid then the T-sum calculations begin, or if you have neonicotinoid dressed seed then the calculations begin at the end of the protective period of the insecticide seed dressing, she says.

“However in light of the current high threat, the follow-up spray may be required sooner than 170 days degrees if high flights continue.”

“If unsure about risk levels the AHDB Aphid News alert is really useful and worth signing up to. “

(https://cereals.ahdb.org.uk/monitoring/aphid-news.aspx)

 

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About The Author

John Swire - Deputy editor of Agronomist and Arable Farmer as well as responsibility for the Agronomist and Arable Farmer and Farm Business websites. After 17 years milking cows on the family farm John started writing about agriculture in 1998 and has since written for a variety of publications and has developed a wide circle of contacts within the industry. When not working John is a season ticket holder at Stoke City and also of late has become a fitness freak, listing cycling, swimming and walking as his exercises of choice.