Vegetable and Forage Brassicas – Late August 2020

Pests

Cabbage root fly egg laying is still underway but has dropped off as the tail end of the 2^nd generation drags out due to the wet weather. Cyantraniliprole can still be applied as a drench treatment to crops in the field such as brussels sprout, cabbage, cauliflower, broccoli, turnip and swede but time for effective control is just about running out. Note that no more than two applications of a Cyantraniliprole product should be applied to a crop in any season and avoid spraying within 5 m of the field boundary to reduce effects on non-target insects. Spinosad can be applied as a foliar drench spray but check the label for approved crops. Some forage brassicas such as kale can receive a spinosad treatment as an Extension of Authorisation for Minor Use (EAMU – 20150102).

Diamondback moth are still being caught in our pheromone traps indicating that 2^nd generation of moths are still laying eggs. Look for caterpillars or eggs on crops and consider an insecticide treatment where found. Note that diamondback moth are capable of laying eggs through some types of mesh or if mesh is damaged or stretched (as can cabbage root fly). Diamondback moth caterpillars may well be resistant to pyrethroid insecticides, so growers may need to use spinosad, indoxacarb, cyantraniliprole or Bacillus thuringiensis as an alternative. Check product labels for specific crop approvals and also check for crop specific EAMU’s for these and other insecticides such as chlorantraniliprole.