Strawberry growers are being advised to use autumn clean up sprays of Calypso to prevent aphid infestation next spring.
Growers have struggled over the last two years as standard aphicide programmes using chlorpyriphos and pirimicarb have been less effective, according to Bayer CropScience.
Professor Jerry Cross said resistance problems are arising” “The melon-cotton aphid is known to be resistant to OPs and carbamates but it now seems that susceptibility to them is changing in all species.”
He considers the most troublesome species are the potato aphid and the melon-cotton aphid; easier to control but also a problem are the shallot aphid and the strawberry aphid. The threat of resistance demonstrates the need for an alternative insecticide from a different chemical family to control all four species.
Jerry Cross’ team at East Malling Research are undertaking a wide ranging HortLink project (HL0191) looking at minimising residues from insecticides and fungicides in strawberries which has included controlling aphids using autumn spraying. The results from two years of on-farm trials using the neonicotinoid Calypso, which has a SOLA for outdoor and protected crops, are excellent.
Last year, a protected table-top crop of everbearer Elsinore at Arnold Farm, Langley, Kent was treated with single sprays of Calypso from the fourth week in September to the second week in November.
All timings greatly reduced potato aphid numbers when assessed in spring, from 400 aphids per 100 leaf sample down to less than 50 aphids. The second week in November was the most effective timing.
Cross added: “Using Calypso as a clean-up spray in autumn to prevent aphid infestation in the following spring is a good tactic. It can effectively control the two aphid species which overwinter in strawberries - the strawberry aphid and the potato aphid - and being from a different chemical group is likely to control strains resistant to OPs and carbamates.”
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