Pushback on disease affecting brassica crops
A team led by Punjab Agricultural University, India, with researchers from The University of Western Australia, reports a breakthrough in disease resistance in brassica crops.
Grant used DuPont Exirel to kill caterpillars and aphids and to also promote beneficial insects in the crop.
“We thought to give it a go because we’d done a trial [the previous year] and it seemed to work. If it leaves the ladybirds and stuff as well, they are killing things for free.”
The Taupo property is used to fatten young stock for quick turnover. Brassica crops are planted from November and fed June-September when grass growth is low.
Grant says a range of insects appeared in the crop and were particularly active when the brassicas were stressed. “As soon as it gets dry they are here in abundance and we seem to get every insect pest you can imagine – not just one or two.”
Retaining the beneficial insects in the crop seemed to help keep the pests at bay, a better option than using chemistry that took everything out.
“That was the old way of thinking - to go in there and blast everything so you have got nothing, but now things are starting to change,” Grant says. “We can’t just keep blitzing things because otherwise we will end up with nothing.”
He says in the past with multiple sprays of alternative chemistry the aphids, in particular, had caused major issues. “We had problems with aphids. No sooner had you killed those little buggers than they would be back again.”
Last season the brassica crops had a first spray four weeks after germination then a spray of Exirel insecticide four-five weeks later, the last insecticide spray for the year.
The brassica plugged the winter feed gap and were much cheaper than buying in feed.
