Chemical Management

There are several insecticides registered against green peach aphids. However many populations of green peach aphids have developed resistance to multiple classes of insecticide.

Currently, the green peach aphid has high-level, target site resistance to synthetic pyrethroids and carbamates, making field rates of these chemicals totally ineffective against resistant populations.

There is also widespread, low-level metabolic resistance to organophosphates and neonicotinoids. Metabolic resistance means that resistant populations are able to detoxify chemicals faster than susceptible insects, so whilst control failures might not always be seen, their use is still inherently risky.

Some aphid populations have documented sensitivity shifts to sulfoxaflor. It remains an effective insecticide, however requires strategic application to prevent further sensitivity shifts.

There is currently no known resistance to flonicamid or afidopyropen, which have a unique chemical mode of action that makes them useful for pesticide rotation strategies.

Growers are urged to reduce the risk of further insecticide resistance by: Rotating insecticide classes; Avoiding the use of ‘insurance’ sprays; Applying insecticides only after carefully monitoring and correctly identifying pest species.

A border spray in autumn/early winter, when aphids begin to move into crops, may provide sufficient control without the need to spray the entire paddock.

Biological Management

There are many effective natural enemies of aphids. Hoverfly larvae, lacewings, ladybird beetles and damsel bugs are known generalist predators that can suppress aphid populations.

Aphid parasitiod wasps are specialist beneficial enemies that are active all year round, with a single wasp controlling >300 aphids. Parasitoids lay eggs inside bodies of aphids that develop and kill their host. Evidence of parasitism is seen as bronze-coloured enlarged aphid ‘mummies’. If mummified aphids make up 10% of the total aphid population within a paddock, it is likely that the majority of remaining aphids have also been parasitised. This is an indication that the population is likely to crash within 2 weeks. Aphid parasitoids that target green peach aphid include Aphidius colemani and Diaeretiella rapae, and are available to purchase for release.

Naturally occurring aphid fungal diseases (Pandora neoaphidis and Conidiobolyus obscurus) can also affect aphid populations.

Cultural Management

Control summer and autumn weeds that act as alternative hosts between growing seasons, particularly wild radish, wild turnip, capeweed and volunteer lupins. Weeds of the brassicae and asteraceae family may also act as hosts for turnip yellows virus and should be removed. Weedy green bridges should be removed at least 10 days prior to sowing.

Conduct regular monitoring for green peach aphids during the risk season between April and June, when the autumn aphid migration occurs and there are ideal temperatures for aphid survival and reproduction.

Sow into standing stubble to reduce bare ground, as the contrast between soil and leafy plants acts as a visual cue for aphids when migrating into crops.