Published on 26/01/2022
Both the grey cabbage and green peach aphid literally love brassicas to death, sucking their plant sap, transmitting viruses and leaving feeding wounds that are an open invitation to disease.
They may be tiny, but they’re prolific – a single adult produces about 25 nymphs which in summer can mature to a reproductive state in as little as seven days. And that means they can build to damaging numbers surprisingly quickly, causing significant loss of dry matter which will be needed later when grass is not enough.
The good news is that a team of other insects like to eat aphids, including brown lacewings, ladybirds, hoverflies, parasitic wasps and predatory mites. These beneficial insects are your farmers’ first line of defence against aphids in brassica crops, but some insecticides kill them as well as the aphids.
Integrated pest management (IPM) wasn’t such a widespread control technique when Transform with Isoclast was first registered for aphids in forage brassicas in 2017. Now, however, there is much more awareness of IPM and the value of beneficials, and that in turn means when aphid populations do blow up, more farmers are looking for selective rather than broad spectrum control.
Glen Surgenor, New Zealand marketing manager for Corteva Agriscience, says this time of the season is when Transform comes into its own for forage brassicas.
Transform features a novel active called Isoclast (Group 4C), which acts systemically for fast knockdown and residual control of aphids. Unlike other common insecticide groups, it is selective to key beneficial insects which naturally help control aphids. But it also has some other notable technical benefits that make it a good fit.
Key points of difference include Transform’s ability to provide longer residual control than some of the alternatives, he says. “Under UV light it doesn’t volatalise and disappear. It is systemic, moving through the plant and protecting new growth, and it also creates a reservoir in the leaf which resists wash-off, so farmers end up with up to three weeks control.”
Aphids sprayed with Transform stop feeding within 20 minutes, Surgenor says, which is a valuable attribute, given their tendency to act as vectors for disease. “This helps stop the spread of virus.”
Isoclast has no cross resistance with other insecticides, making Transform an ideal rotation partner for resistance management strategies involving aphicides with other modes of action.
End users have welcomed its strong environmental and toxicology profile, because it provides a high level of safety for both ground and aerial based applicators.
To expand the pest spectrum and provide exceptional control across all the main pests of forage brassica crops, Transform can be easily tank mixed and applied with Sparta. In addition to aphids which Transform controls, Sparta adds diamond back moth, white butterfly, loopers, leafminer and springtails.
Transform is also compatible with commonly used forage brassica herbicides including Korvetto, Milestone, T-MAX, Radiate and Versatill PowerFlo along with Uptake™ spraying oil.
Thorough coverage of forage brassica leaves is essential, especially as the crop matures. For ground applications, farmers should use at least 250 litres of water per ha, and for aerial, 50-100 L per ha.
Ultimately, however, farmers (and retailers) should always try and be proactive with pest management, Surgenor says. “The more aware you are about the presence of different insects, and the difference between beneficials and others, the better. Close, regular crop monitoring is always the first step to growing healthy, high yielding brassicas.”
For more detail contact your Corteva Agriscience territory sales manager.