Green peach aphids

With only a few reports of green peach aphids in canola, and no virus symptoms, the season appears to be getting off to a good start

 

Where have they been reported?

A small number of canola crops at the cotyledon-1st true leaf stage in Victoria’s Northern Country have been found with green peach aphids. In one paddock west of Echuca, there were large numbers of aphid nymphs on leaves and cotyledons. The aphids occurred at densities of 4-5 per leaf and were spread across the paddock. The aphids seemed to have survived a seed treatment indicating potential issues with resistance.

About this pest

The green peach aphid (Myzus persicae) is a pest of many crops but primarily attacks canola, lupins and other pulse crops. They are most common in autumn and seldom cause economic losses to crops through direct feeding. However, it is an important vector of several plant diseases including beet western yellows virus (BWYV). For detailed information on this pest, including their occurrence, lifecycle, behaviour, damage symptoms and management strategies, go to the new PestNote on green peach aphid.

Our advice

When virus risk is considered low, monitoring to assess the risk of direct feeding damage should begin in late winter and continue through early spring. Aphids will generally move into paddocks from host weeds or volunteer plants located on roadsides, paddock edges or neighbouring paddocks. Damage often appears initially on crop edges, which should be monitored. Inspect the underside of plant leaves. Aphid distribution may be patchy, therefore monitor at least five representative sampling points across the paddock. Inspect at least 20 plants at each sampling point.

If chemical control is required, be aware of the species present and keep in mind that green peach aphid populations have widespread resistance to several insecticides, including synthetic pyrethroids, organophosphates and carbamates (e.g. pirimicarb). It is important to rotate insecticide classes to help prevent resistance from developing further. Growers are encouraged to follow the new resistance management strategy for green peach aphids and keep an eye out for any control difficulties that arise when applying chemicals as per label instructions.

Below Dr Paul Umina (cesar) discusses the management of green peach aphid and BWYV in detail with GRDC in February 2015.

 

Source of field reports of green peach aphids

Duncan Thomas – Agronomist, Landmark (Victorian Northern Country)