Synthetic pheromones foil pea midge attacks
Synthetic pheromones foil pea midge attacks
By Andrew Swallow
ADVANCE warning of pea midge attack looks set to save vining growers unnecessary sprays and severe yield losses, says the Pulse Growers Research Organisation.
Currently growers follow a programme of routine spraying in midge prone areas for fear of yield losses as high as 70%.
But the identification and synthetic production of midge pheromones means effective trapping is now possible, claims PGROs Anthony Biddle. That will allow growers to wait until the pest is observed before applying an insecticide spray.
"It will give growers a couple of days warning of attack."
Attracted midges
Trials with the pheromone in the East Riding, Yorks, attracted midges immediately earlier this month, in what is currently the most midge prone region in the country. Now commercial traps and thresholds for applications need to be developed, says Dr Biddle.
Midges emerge from over-wintered pupae in the soil in fields which grew peas, vining or combining, in the previous season. Hence, this would be the best place for traps, he says.
"They emerge and mate in the same morning. Then the female flies off to settle in a susceptible crop and lay eggs just a day later. It is a very tight window to control them before they lay."
Crops are only susceptible at the bud stage, as eggs are laid on the flower buds. The larvae then bore into the bud, making it sterile. In addition to direct feeding damage, the plant reacts to the attack, shortening the internodes resulting in a cabbage or nettle-like head to the plant. "It can be absolutely disastrous," he notes.
The pheromone breakthrough in pea midge control is the culmination of fifteen years work by the PGRO and the Swedish University of Agriculture, near Malmo. *