Pest Management in Vegetable & Forage Brassicas – Early June 2020

First-generation cabbage root fly egg-laying and the onset of egg hatch is now well underway and will have been exacerbated by warm sunny weather, so any uncovered crops will be at risk.

We are at around the peak of egg-laying just now, and at our monitored crops about two-thirds of the eggs laid have hatched, so time is running out to apply allowable control options to uncovered crops.

If flea beetle damage is occurring to emerging crops, then a pyrethroid insecticide treatment can be used. If it rains this will keep the beetles off plants as they prefer drier conditions.

Diamondback moths and silver Y moths have been found in traps in some monitored crops. Growers should check crops for eggs and young caterpillars and apply control measures where necessary.  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.  Check product labels for specific crop approvals and also check for crop-specific EAMU’s for all insecticides.

Site specific advice can be sought from your local agricultural advisor or agronomist.