Aphids

The winged form of the cabbage mealy aphid (Brevicoryne brassicae) usually lands on the crop in early June and small colonies of young aphids are visible in early summer. Aphid numbers build up over the summer months and once well established can be difficult to control. Unfortunately options for good control are limited.

Triazamate (Aztec) is a systemic insecticide with approval for use on cabbage (excluding savoys) and sprouts. Growers who used it last year reported good results and this would be the number one choice where it can be used.

Lambda-cyhalothrin + pirimicarb (Dovetail) has contact, fumigant and translaminar activity. It also has insect repelling and anti feeding activity.

Pirimicarb (eg Aphox, Pirimicarb, Phantom) has contact, fumigant and translaminar activity and should be applied as soon as aphids first seen. It works best in warm conditions. It will not kill aphid predators so allowing these to build up within the crop.

Pirimicarb + deltamethrin (Evidence, Patriot) will have longer persistency than pirimicarb on its own.

Cabbage white butterflies (Pieris rapae, Pieris brassica) will soon be laying eggs in brassica crops. Caterpillars will hatch from eggs in 6-10 days (depending on weather) and start feeding on the leaves of the crop. They are relatively easily controlled as their feeding habit leaves them exposed and susceptible to contact pesticides. The most popular option is cypermethrin (various formulations including Toppel 10).

The diamond back moth (Plutella xylostella) lays its eggs in small clumps on the underside of leaves. The small caterpillars feed on the underside of the leaves leaving the upper surface intact. Although small these caterpillars can do a lot of damage if numbers build up. As they are on the underside of the leaf they are protected and therefore are harder to kill than other caterpillars.

Alpha-cypermethrin (Contest, Fastac) is probably the best choice of chemical. However its persistence is short so at least two treatments will be necessary.

Diflubenzuron (Dimilin Flo) primarily affects the young caterpillar, preventing it moulting and proceeding to the adult stage.

Lambda-cyhalothrin (Hallmark with Zeon Technology) will give some control but again more than one treatment will be necessary.