Transform™ is a new insecticide that has recently been registered for woolly apple aphid (WAA) in Australia. It has a new mode of action and belongs to a newly created chemical class.
It only has a 7 day withholding period, which may be of benefit to control any late season woolly aphid flares, that may occur as harvest approaches.
Growing problem
WAA appears to be increasing across Australia. Once the pest is established in an orchard it is rarely eradicated, and becomes an annual management issue to keep it under control.
Changes in orchard rootstocks (M9 and M26) and microclimate (protective canopies) have resulted in more favourable conditions for WAA to prosper.
Nursery trees have been known to carry the pest on the roots, so treating young trees with an insecticide prior to planting should be employed to minimise any risk of transporting WAA from the nursery to the orchard.
Extreme heat during the season and/or toxic broad spectrum insecticides (e.g. Lorsban) can also upset biological predators such as Aphelinus mali, and earwigs.
Issues resulting from infestation
The three main issues associated with woolly aphid infestations are:
- The secretion of honeydew which falls onto fruit. Sooty mould can develop on the honeydew reducing the marketability of fruit
- Orchard workers can complain about the effects of the aphid
- Severe aphid infestations can kill shoots and reduce the viability of buds for following seasons.
Control options for apples
It’s been a few years since we had a new insecticide registered to control woolly aphid, dimple bug, and mealybug in pome fruit.
I expect Transform will be welcomed by many orchardists, since we only have limited options available for those practicing IPM.
Transform is reported to have minimal impact on beneficial insects and predatory mites, so it should be a good option for growers looking to control WAA without upsetting local beneficial insect populations.
For more information and a table of products, see Tree Fruit November 2013
