August aphid and whitefly update
Peach-potato aphid activity in Lincolnshire escalated through June and peaked early in July with the RIS Kirton trap catching 1,186 in the week 4th to 10th July. The usual mid-season crash followed and numbers in vegetable brassica crops are currently very low according to UAP agronomist Dan Hayes.
This year he again found whitefly coming into Lincolnshire crops about a month earlier than usual, in late May to early June. Movento (spirotetramat) treatments were deployed to prevent populations building up and also to control the increasing number of winged aphids migrating into crops at that time.
These did a very thorough job of controlling both sucking pests he reports. “It’s important to get the first Movento spray on at the early signs of whitefly, to target the larvae, as it takes a little time for its two-way systemicity to take effect. Within two to three weeks from application it breaks their life cycle and leaves a very clean crop.”
These initial treatments were followed with Biscaya (thiacloprid) or Plenum (pymetrozine) during June or July to control subsequent whitefly ingress and continued aphid migration.
With longer season crops, particularly Brussels sprouts, Dan is now watching and waiting to see what develops. “Crops are looking good but, aphids and whitefly can build up again any time from late August into September, depending on conditions and predator numbers. Close monitoring of crops is key to keeping a handle on the situation.”
Should aphids or whitefly require control from here on, timing of the second Movento application will be critical he emphasises. “The aim is to maximise protection of button quality through to harvest so you don’t want to use it too early. But it also has to go on while plants are still actively growing so the vascular system can transport it to target these hidden pests.
Last year, when sprout crops were under sustained and heavy whitefly pressure right through the growing season, Dan found the strategy of two well-timed Movento sprays, with Biscaya and Plenum sprays sandwiched in between them, delivered excellent results.
“Marketable yield was vastly improved, button quality was saved from contamination and they were bigger too. It also dramatically improved harvesting conditions for the pickers who didn’t have to contend with the usual clouds of whitefly coming off crops.”
