Control of woolly aphid with soil-root drenches and foliar insecticides

2015–16 | Angus Crawford, APAL, and Petar Bursac, Fruit Growers Victoria | Future Orchards® trial report

Woolly apple aphid is challenging because colonies can occur both above ground and on roots, where foliar sprays cannot reach them. This Future Orchards® demonstration trial compares insecticide strategies based on foliar treatment, soil-root drenches and a combined approach.

The report records strong canopy control from systemic foliar treatments and shows why root-zone management may still be required where underground colonies are established. It also notes practical factors affecting soil drenches, including soil moisture, weed-free application zones and the need for active roots to take up product. In the trial, foliar applications achieved very high canopy control, while control at the trunk base was less complete; root-drench treatments likewise did not provide complete stand-alone control at every part of the tree.

The trial supports an integrated approach to woolly aphid management: identify infested trees, protect biological control where possible, and select treatment methods according to where colonies are located. Current labels and resistance-management guidance should always determine present-day product use.