NovaChem > Industry News > 2023 > Help at hand for FAW surveillance this season

Help at hand for FAW surveillance this season

Published on 21/11/2023

If you don’t know, it’s time to find out!
Why? Because the better you understand the FAW lifecycle in
your region, the more accurately you will be able to predict when larvae might be appearing in crops.
Nicole Morris, technical specialist for Cor
teva Agriscience, says because the pest is so new, there’s still a lot for growers to learn about the process of capturing and utilising population data to refine their control programmes.

She’s spent winter and early spring working
with Corteva’s distribution partners and other industry groups to help prepare for what will be New Zealand’s second maize growing season since FAW was confirmed to be established and spreading here last autumn.

Two topics have been high on the list of pri
orities – understanding the FAW lifecycle, including correct larvae identification; and knowing the economic threshold for crop damage.

Both feature prominently in the FAW Field
Guide Corteva has just published for agronomists and reseller reps to carry with them on farm visits this spring.

With three other caterpillar species present
in NZ maize crops, being able to differentiate FAW larvae from others is a critical first step towards better management, Morris says. 
Likewise understanding the behaviour of different larval stages is a must for effective control where required.
It all comes down to frequent crop scout
ing, so growers can make an informed decision about when to treat with Sparta (Group 5 insecticide), and apply it when larvae are still small.

“The ideal size for Sparta application is
when larvae are between the first and third instar – this is the most economic time to treat. Between the fourth and sixth (final) instar, they become larger, eat more, cause more damage, and move down into the whorl, where they become what we call entrenched and can avoid the insecticide.”

However, deciding to spray is not as simple
as finding larvae in the crop. Several other factors must be considered, including the number of injured plants, and the severity of that damage.

This is where the Davis scale helps quantify
what’s going on. Ranging from 0 (no visible damage) to nine (whorl and furl leaves almost totally destroyed), it provides a visual prompt to assess different levels of crop injury.

Every stage is illustrated with photos in Cor
teva’s FAW Field Guide.

The handy new resource also includes ad
vice on making best, and most sustainable, use of Sparta, which is still the only insecticide specifically registered in NZ for control of FAW in maize and sweetcorn.

Resistance management is of key impor
tance, Morris says.

“There are no known cases globally of re
sistance to Sparta, and we want to keep it that way.”

Repeated exposure of multiple pest genera
tions to the same mode of action can result in selection pressure for resistance, and FAW is no exception.

In maize, Sparta should not be applied
more than twice per crop, and an effective insecticide with a different MOA should be used between Sparta treatments.

Morris says feedback from growers who
used Sparta last season has been highly positive.

“Thorough spray coverage is essential for
successful control growers should read the label, and use the correct rates of Sparta and water for either ground or aerial applications.”

For further detail, including help with identi
fying FAW larvae, contact your local Corteva territory manager.

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