GREEN peach aphid resistance to insecticides has escalated across Australia, with many canola growers failing to gain effective control over this serious pest last season.
This has major implications for both broadacre and horticulture crops.
A Grains Research and Development Corporation (GRDC) funded survey in 2013 found that green peach aphid had developed resistance to more insecticides than any other insect pest – documenting widespread resistance to synthetic pyrethroids, carbamates and organophosphates.
GRDC is urging growers in all Australian mainland cropping regions to rotate chemical groups and to take advantage of biological controls to extend the useful life of available products – and to avoid a future of inadequate and failing control over this serious sap-sucking and virus-carrying pest.
Technical consultant to Crop Care Glen Tucker said it wasn’t only grain, canola and pulse-crop growers’ use of insecticides that was contributing to the problem.
“Earlier CSIRO research in Victoria, New South Wales and Queensland grain crops found much higher green peach aphid resistance to insecticides in areas where vegetables were widely grown,” Mr Tucker said.
“In the same study, CSIRO also reported low-level resistance to imidacloprid in New Zealand potato crops.
“The 2013 GRDC survey then found evidence of potential imidicaloprid resistance in some Australian cropping areas. This is of great concern.”
He said any vegetable, fruit and nut growers around Australia having problems controlling aphids this season were likely to be facing similar resistance to a number of the currently-used insecticide groups.
“It is imperative that all growers put in place a resistance-management strategy this season, including monitoring, chemical-group rotation and avoiding the use of cheap, broad-spectrum ‘insurance’ sprays,” he said.
Mr Tucker said a new, systemic horticultural insecticide Endgame 500WG – from a different chemical group (Group 9B) to those showing aphid resistance – had been registered by Crop Care late last year.
“Endgame provides vegetable and fruit growers with a timely alternative for effective control and resistance management of green peach and other aphid species in brassica, potato and stonefruit crops,” he said.
Current permits also allow its use against aphids and whitefly on a wide range of other crops including cucurbits, broccoli, sweet corn, eggplant, almonds, lettuce, chicory, endive, radicchio, snow peas, sugar snap peas and cut flowers; plus cucumbers, capsicum, eggplant, lettuce and tomatoes grown in protected situations.
“Endgame contains pymetrozine – an insecticide that has not been widely used, so is less likely to encounter resistant aphid populations, at least in the short term,” Mr Tucker said.
“Targeting only plant-sucking insects, it is also considered IPM-friendly, allowing beneficial predators and parasitoids to help suppress aphid numbers.”
He said growers would see a different response to treatment with Endgame.
“It’s a systemic anti-feedant, stopping insects feeding within 15 minutes. Aphids may remain on treated plants for a few days, but are incapable of further feeding and will ultimately starve to death.”
“So it is very important to treat the crop at the first sign of aphid infestation and before there is significant feeding damage.
“In potatoes and brassicas it is also very important to achieve good coverage, and to use a suitable wetting agent to maximise Endgame entry into the leaves.
“It is recommended Endgame be applied as a spray in a minimum of 100 to 800L of water per hectare (depending on the size and stage of the crop) via hollow cone nozzles and droppers. The product is rainfast within two hours.”
For aphid-resistance management and to extend the effective life of this novel control, Mr Tucker said growers should apply a maximum of two sprays of Endgame (or other Group 9B insecticides) per crop, and not as consecutive sprays.
“It is imperative that growers and consultants adhere to the resistance management strategies recommended by CropLife Australia for green peach aphid and melon aphid control, to preserve the usefulness of aphicides.”
