Crops are now generally past the risk of pollen beetle damage.
With crops now mostly flowering in earnest and petals beginning to fall in advanced crops, the general picture is that this year’s winter OSR is now safely past the risk of pollen beetle damage. From her experience of tracking pollen beetle migration through recent springs Rothamsted researcher Dr Sam Cook highlights a recurring pattern.
“This year crops have again won the race against pollen beetle, by reaching flowering before beetle numbers have built up to be a cause for concern. For the last four seasons we have observed this pattern with crops reaching this point in the middle of April when there is still further migration to come.”
The Bayer pollen beetle predictor ‘percent migration’ map is now showing migration mostly done across the south east of England with the remainder of the country largely ranging from two thirds to three quarters complete. Three weather stations are showing migration complete; Amersham, Harlow and Welwyn Garden City.
Dr Cook adds that backward crops she has been monitoring at Rothamsted sites near Welwyn, came close to thresholds in the first week of April but narrowly avoided the need for treatment by reaching flowering just in time.
As usual migration in Scotland has been later than in England and the ‘percent migration’ map is now showing from 19% at Huntly to 41% in the Borders at Berwick and Coldstream. However, Bayer’s Neil Thomson confirms that crops north of the border have generally reached 10% flowering and are past the damage susceptible stage.
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