Need for change in diamondback moth management
- Grower Stories
01 May, 2020
- Grower Stories
01 May, 2020
Faced with their highest ever infestation of diamondback moth larvae in brassicas at the start of the 2019/20 season, Lockyer Valley grower Paul Windolf tried a new approach to controlling one of their most damaging pests.
The family owned and run vegetable business, based in Tenthill, Lockyer Valley, produces winter vegetables, potatoes and summer pumpkins.
With an attitude of ‘if what you're currently doing is not working, maybe it's time to change’, Paul hosted trials on Windolf Farms this year focussed on beneficial insects and softer chemistry to control diamondback moth, with promising results
It’s an approach championed by Dr Paul Horne from IPM Technologies, who ran a workshop organised by Bayer at Windolf Farms on the subject in January this year.
“Traditionally, control of damaging pests in many crops has relied on the use of pesticides alone, including products that kill naturally occurring beneficial species, such as insect predators and parasites,” Dr Horne explains.
“Therefore, there is a total reliance on insecticides and when that approach fails due to the pest developing resistance, then there is a crisis.
“Brassica growers in Australia now have either reached that point in parts of Queensland, or are about to face that crisis, in most mainland production regions.”
Dr Horne says a change of approach is required where beneficial species can assist with control, including many naturally occurring species and also by releasing diadegma wasps, which are also produced commercially.
“This involves a change in the types of insecticides used for all pests, not just for diamondback moths,” he explains.
Diadegma wasps have been trialled at Windolf Farms as an additional control tool in a five-hectare block of broccoli. The wasps parasitise diamondback moth larvae, providing an effective control strategy in combination with softer chemical options.
“Our approach was to do two releases of wasps, at week two and week four, in conjunction with several soft chemical sprays,” Paul Windolf says.
“It hasn't been difficult. We just have to be more aware of our spray applications, because you put the wrong chemical out, you can do more damage than good in the crop.
“We've harvested the broccoli and we've had quite a good result. Pack-outs are good and no evidence of live diamondback moth larvae.”
To help the beneficial wasps, the Windolfs have planted alyssum around the broccoli fields, which acts as a nectar source and a place for them to take shelter. Mr Windolf says the strategy has been effective, as his crop checker is generally able to find diadegma around the planted flowers.
Introducing diadegma into the suite of diamondback moth management tools has also prompted the increased use of ‘soft’ insecticide chemistry.
“We’ve been using products such as Movento®, an insecticide from Bayer, and Bt’s, which has been an important strategy as these chemicals are safe for most beneficial insects,” Mr Windolf explains.
“Despite the start of this season producing the highest pressure of diamondback moth we've ever had, we still had a great result with this system. It's very pleasing to see the end product, it's very clean.”
Movento® is a Registered Trademark of the Bayer Group