In the heart of brassica growing country in the Werribee region of Victoria, diamondback (DBM) moth is a pest you simply cannot take your eye off.
The Zanghi family, who grow cauliflower, cabbage and broccoli over a 40-hectare property in the region’s south, said they have to keep on top of DBM continuously.
“There are other grubs that we have to take care of as well, but DBM is the main target,” says Andrew Zanghi.
“There’s always going to be (insecticide) resistance developing and a different chemical that we need to put into the rotation for DBM.”
Daniel Polson, southern market development manager – horticulture with Adama Australia, said some of the Helicoverpa species as well as DBM presented challenges in the region.
Mr Polson said these insect species have short life cycles, with populations increasing as the season warms, and they can rapidly develop a tolerance or even resistance to existing chemistry.
“This becomes a major problem, as the early life stages of the moth is a caterpillar that grows in size through four stages. Early instars tunnel inside the leaf and, as they develop, they will then feed on the underside of leaves, contaminate cauliflower curds and broccoli florets and damage the heads of cabbage and Brussel sprouts.
“Female moths can lay more than 150 eggs and there can be six to seven generations per year, which will overlap through the warmer parts of the season.”
He said there was strong pressure on growers to control the pests because market tolerance for feeding damage was very low and they had to deliver produce to a high standard. It must meet all fresh quality assurance controls, accreditations and compliances, including insecticide maximum residue limits.
At the Zanghi’s property, crop cycles can range from 12 weeks in the summer through to 18 weeks over winter.
Mr Zanghi said they applied insecticides about every 10 days leading into summer, whereas winter applications can be every two to three weeks.
“Depending on weather conditions and pest pressure, we start applying insecticides about two weeks after plantings to combat DBM.”
With an interest in new insecticide developments, Mr Zanghi earlier took advantage of an opportunity with his local supplier, EE Muir & Sons, to trial Plemax insecticide against DBM in his cauliflower crops and then in broccoli the following season.
Plemax has introduced a new mode of action, novaluron (Group 15), in combination with the trusted strength of indoxacarb (Group 22A) for tackling chewing pests in brassica as well as leafy and fruiting vegetable crops.
Mr Polson said indoxacarb already is a widely used knockdown insecticide and its unique combination with novaluron, a slower mode of action insect growth regulator (IGR), has improved treatment efficacy and reduced the risk of resistance developing.
Both also have similar residual activity and rainfastness, further increasing the likelihood of target pests ingesting the active ingredients.
DBM was the main focus of the company’s recent trials with Plemax in the Werribee region, coordinated to help agronomists and growers understand how best to use the insecticide in their spray programs.
Mr Zanghi said he was impressed with the results of the trials on his family’s property.
“There was a lot of pressure in the trials and Plemax really did outweigh everything else that was applied. There were a range of treatments against DBM and Plemax performed the best out of all of them,” he said.
“It provided good protection and the result was a clean crop and good yields.
“It also handled really well, went out through the boom well and there was no effect on the crop.”
Mr Zanghi said introducing Plemax into their pest control program was a good step to help extend the life of other insecticides they used as well.
“From now experiencing it in the trials, in our crops and in our spray program, we will definitely keep using it.”
Mr Polson said the indoxacarb in Plemax acted quickly to stop pests feeding and causing damage, while the residual properties of novaluron acted on eggs and instars hatching after spraying, so early season applications were ideal.
“With the novaluron sitting on the leaf, as they feed it stops them from metamorphosising into the next larva stage.”
He said Plemax now allowed growers extra options to rotate insecticides, to improve the effectiveness and longevity of existing products used in their programs, and to prevent insect populations from developing resistance on their properties.
“Growers can combine Plemax in programs with other chemicals to achieve long-lasting control throughout the season. Crop safety and compatibility was an important part of its testing and there were no problems with its compatibility with other insecticides and fungicides or its phytotoxicity with the crops on label.”
Mr Polson said grower uptake of Plemax was steadily increasing year-on-year.
“They are recognising the benefits of its dual mode of action, its role in maintaining the efficacy of their existing insecticides, and its ability to improve yields and achieve a much higher quality standard of produce,” he said.
