Cotton

New resistance management plan for Bollgard III

Liz Wells, September 1, 2016

THE COTTON industry’s Transgenic and Insect Management Strategies (TIMS) Committee has developed a new Resistance Management Plan (RMP) that growers planting the new Bollgard III varieties must adhere to.

Compared to the RMP for Bollgard II, the Bollgard III RMP includes a wider planting window, reduced refuge area requirements and changes to the pupae busting conditions.

CottonInfo technical specialist, Sally Ceeney, said the overall aim was to produce a balanced RMP that was scientifically robust, practical and achievable for the grower:

Sally Ceeney

Sally Ceeney

Planting windows:

The aim of the planting window is to reduce the length of time the pests are exposed to the toxins.

We know that in the southern regions that climate is the biggest driver of planting time and the season length.

The planting window still plays a role in the warmer regions (northern) where the season length can be potentially longer.

The biggest risk in terms of planting length occurred at the end of the season with late crops and regrowth, rather than at the start of the season.

So what we have ended up with is a wider planting window with some more flexibility built in around that.

Now that we have a wider planting window, the RMP has a stronger focus on reducing end of season risk, ensuring crops are destroyed in a timely manner and we don’t have regrowth occurring.

Pupae busting:

While pupae busting can be a highly effective tool, there is no point pupae busting fields if there are no pupae in the soil to kill.

We wanted to make sure growers only had to pupae bust in high risk fields.

So the dates around pupae busting have changed. There is no longer a requirement to pupae bust early fields where you are defoliating before March 31.

It is based on the first average date in most regions where the likelihood of pupae entering diapause is 50 percent.

The rules have also changed around what areas of the field to target. Growers are now being asked to target the hills rather than the furrows where there is more likely to be diapausing pupae.

So while we might have fewer fields each season that are being pupae busted, those that are being pupae busted are much more highly targeted.

Refuges:

Growers are required to plant pigeon pea or unsprayed, conventional cotton as a refuge for Helicoverpa.

Under Bollgard III, the refuge requirements for pigeon pea and unsprayed cotton have been halved: 2.5pc for pigeon pea and 5pc for unsprayed cotton.

This reduction represents the industry’s confidence in the three-gene technology, it is not a reflection of a reduced importance of refuges.

 

RELATED ARTICLE: New generation Bollgard III to blitz cotton plantings

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