Preventing a spring flush of aphids in vegetable crops
Aphids cause damage in many vegetable crops. While different species of aphid are active at different times of the year, warmer temperatures in spring are a catalyst for many species to accelerate their reproduction.
The various aphid species differ in characteristics such as appendage and body colour, and wing vein size, but most are small 1.5 to 3 mm, bulbous insects with thin legs. They can be winged or non-winged as adults. Winged species readily infest other host plants while non-winged aphids and nymphs are usually found in high numbers feeding on plants. Aphids can reproduce quickly. Some reproduce by telescoping generations with females carrying developing daughters who also carry their own developing daughters to be born live, not laid as eggs.
The sap feeding nature of aphids causes stunted plants, leaf curling and some discolouration. While high numbers of aphids cause yield losses, their biggest impact on plants is how they spread viruses such as mosaic virus in lettuce and brassicas, and potato virus Y and potato leaf roll virus.
To control aphids in lettuce and brassica crops, one option is to treat seedling transplants in cell trays with Durivo®. Pirimor® 50 and Chess® WG are registered for aphid control in potatoes, lettuce and brassicas. Transform® has registration for controlling aphids across many crops, including a range of vegetables, cereals and forage brassica crops. Potato specific options include Benevia®, Mainman® or Movento® 150 OD. Note that these three options also control tomato potato psyllid and work in integrated pest management programmes.
Aphids are a food source for predatory beneficial insects such as hoverflies, ladybirds and brown lacewing. Parasitic wasps also offer biological control by laying their eggs inside an aphid. The resulting larvae feed inside the aphid until they emerge as an adult, causing the parasitised aphids to take on mummified appearance.
For more information on controlling aphids in vegetable crops, speak to your local Fruitfed Supplies Technical Horticultural Representative.
