Almond and pistachio growers have long used pheromone traps to get a handle on navel orangeworm populations in making treatment decisions.
However, the reliability of these traps declines once the crop reaches the point where the nuts are more attractive to the females than the bait used to lure them to the egg traps. Also, the eggs are so small, it’s difficult and time-consuming to get an accurate count.
This year, for the first time, growers have an alternative — traps that attract males. Called Biolure from Suterra, they feature a long-acting pheromone that can be used to track NOW flights even after hull split or after harvest.
This new tool retains its efficacy for up to six weeks under normal conditions in almond orchards and can be used to monitor male NOW populations for as little as $1 per acre per season in typical trap densities found in California nut orchards, Suterra reports.
Paramount Farms’ research entomologist Brad Higbee has been testing different pheromone lures for eight years and conducted large scale tests of the Suterra product in 2012. USDA research entomologist Joel Siegel, based at the San Joaquin Valley Agricultural Sciences Center, Parlier, Calif., is currently testing them, too. He and other researchers have found the numbers of males recovered to be much larger than the number of females recovered in sticky traps that use ground nuts as an attractant.
“So far, the male traps are working wonderfully,” he says. “They pull in males from a much farther distance than the almond bait traps do in attracting females.”
The appropriate number of male traps to put out in an orchard depends on the purpose of trapping, Siegel notes. Using them to determine biofix probably calls for a different density of traps than using them to evaluate the effectiveness of a spray treatment or mating disruption.
“You almost need a seminar or half a day of discussion to learn how to relate the results of the male traps with egg traps and female capture,” Siegel says. “Growers will have to experiment with this new tool it to see how it fits into their own management program.”
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