02/09/2024

SOME new insecticide tools put to good use in recent years have helped to arrest concerning insect resistance levels for brassica and lettuce growers in south-eastern Australia, however Nutrien Agronomist Sigurd Howard says growers should remain conscious of what can happen if products are not used carefully in the future.

Sigurd has been providing agronomy support to growers through south east Victoria, as well as in the Werribee and Greater Melbourne regions, during two stints with Nutrien over about 15 years.

In addition to iceberg lettuce, the main brassica crops grown through the areas include cauliflower, broccoli and cabbage and the key insects to combat are particularly diamondback moth (DBM), as well as cabbage white butterfly and heliothis.

Sigurd said previous overuse of Group 28 chemistry generated increased resistance to this class of insecticides.

He said the release of Plemax insecticide put one of the most effective tools against the resistance in growers’ hands and its rotation with a number of other alternative options now available had proved powerful.

Developed by ADAMA Australia, Plemax introduced a new insecticide mode of action, novaluron (Group 15), in combination with the trusted strength of indoxacarb (Group 22A), for use in brassica as well as leafy and fruiting vegetable crops.

Indoxacarb has been a proven knockdown insecticide and its unique combination with novaluron, a slower mode of action insect growth regulator (IGR), has improved treatment efficacy. Both also have similar residual activity and rainfastness, further increasing the likelihood of target pests ingesting the active ingredients.

“The novaluron really brings uniqueness to it and we know the indoxacarb helps,” Sigurd said.

“It’s had a great fit in programs because it mixes up the (chemistry) groups. It completely steps away from what we have been doing and has helped to better control insect pest populations and produce a better end product with less physical damage.”

He said in rotation with spinosad insecticide, several biological products and, more recently, isocycloseram insecticide, Plemax had certainly become the proverbial “another tool in the shed” for growers.

The ideal time to apply Plemax, particularly in cabbage and cauliflower, is at the early wrapper leaf stage, ensuring the insecticide can get down into the plants before they closed.

“This is the most effective time to use it, with other options also available to be applied later. We aim for early control and to stop the egg laying inside the cabbage and lettuce, and to target the caterpillars at an early stage,” Sigurd said.

He said with the insect resistance levels and general control now improved, it was important to continue using latest products carefully, and particularly considering the recent expiry of some insecticide patents.

“Rotation, rotation is what it is all about. If you are spraying every 10-14 days, you could be doing up to eight sprays. We don’t want to be doing any more than two sprays of an insecticide product in a crop.”

“For the longevity of control, we are also looking forward to more new products coming along that we can rely on,” Sigurd said.

For further information on Plemax insecticide, growers and advisers can contact their local ADAMA Australia representative or visit https://www.adama.com/australia/en/crop-protection/insecticide/plemax  

*DISCLAIMER:

The information provided in this article is intended as a guide only. Information contained in this article has been provided by the manufacturer/ You should not rely on the information in this article, and it should not be considered advice. You should seek professional advice regarding relevant factors specific to your situation. This article does not take into account variable conditions that may impact performance. Always read and follow label directions before