Early infestations of several aphid species have been reported; continued monitoring and correct identification are important for their management.
Where have they been reported?
Six different species of aphids, including green peach aphids (Myzus persicae), cowpea aphids (Aphis craccivora), bluegreen aphids (Acyrthosiphon kondoi), cabbage aphids (Brevicoryne brassicae), turnip aphids (Lipaphis erysimi) and potato aphids (Macrosiphum euphorbiae) have been recorded feeding on pulse and canola crops across the Victorian Wimmera and Mallee in the last fortnight.
Many of these aphids have been found in higher number on the edges of the crop, indicating a recent colonisation, with lower numbers towards the crop centre that may have been recent arrivals or present in the crop over winter.
This is the second successive season in which we have received samples containing what were thought to have been green peach aphids but upon closer identification were actually potato aphids. The two species look very similar to the naked eye, though potato aphids have a much narrower body compared with green peach aphids, with a sword-shaped tail projecting from their abdomen (see photo). These potato aphids were found within the new flower buds in a paddock of vetch near Manangatang, in the Victorian Mallee.
About pulse and canola aphids
For comprehensive information on aphids that affect pulse and canola crops, including their occurrence, lifecycle, behaviour and management strategies, go to cabbage aphid, green peach aphid, turnip aphid, cowpea aphid or bluegreen aphid within the new PestNote series.
Regular monitoring for aphids, especially in vulnerable crops, is essential during spring.
Aphid distribution may be patchy, so monitoring should include at least five representative sampling points throughout the paddock, with at least 20 plants at each point.
Aphid numbers can build up quickly during spring, but it is important to consider factors such as crop stage, soil moisture, forecasted weather conditions and beneficial insect activity before control measures are taken.
Correct identification of aphids is essential, though often difficult. This is particularly the case if you considering chemical sprays. Some species, such as green peach aphids, have developed resistance to a range of insecticides that means chemical control is difficult.
Sources of field reports
Alana Govender and Garry McDonald – cesar
Andrew McMahen – Agronomist, Landmark (Victorian Mallee)
John Stuchberry – Consultant, JSA Independent (Victorian Wimmera)