New technology reduces cost to disrupt pest's mating
By LISA LIEBERMAN
For the Capital Press
Growers are using several tools in concert with mating disruption to win the battle against the navel orange worm.
The worm has been a problem in California almond and pistachio groves. It is an especially tough pest to kill because it produces several generations a year. That makes it difficult for orchardists to determine the best time to spray pesticides.
Paramount Farms in Bakersfield has drastically reduced damage with mating disruption.
It isn't a "magic bullet," according to Brad Higbee, a former USDA research entomologist. Other practices such as removing mummies from the fields and closely monitoring fields can make a big difference, he said.
"Mating disruption will hold things down for you and give you more of an open window to decide when to spray and when not to," Higbee said.
Traditionally, the navel orange worm damaged an average of 2 to 4 percent of almond and pistachio crops at Paramount. But over the past few years Paramount has reduced damage to as little as half a percent.
Higbee heads the navel orange worm research program at Paramount. Higbee, known for his work with mating disruption pheromones on the coddling moth in apple and pear orchards in Washington state, uses "puffer" pheromone dispensers at Paramount.
While mating disruption technology has been around a long time, the puffers are relatively new. They work like deodorant dispensers in public restrooms. They puff out pheromones at fixed time intervals.
Mating disruption works by releasing synthetic sex pheromones in the field, attracting male moths seeking fertile females. The males become disoriented and can't find female moths to mate with.
This means the moths don't reproduce, and eventually the moth population diminishes.
Most pheromone-based mating disruption devices are enclosed in plastic or synthetic polymers that are diffused over three to six months. Generally, growers hang 400 devices per acre at a cost of $125.
The advantage of the puffers is that growers only need to hang one or two per acre, which in turn reduces labor costs. After an initial investment, they cost about $5 per acre to maintain.
The disadvantage, though, is that if something goes wrong with the puffers, no backups compensate for them.
"The puffers are relatively new technology, and the concern is that if you have one per acre, there could be gaps in coverage with the pheromones and the moths could end up mating," said Jay Brunner, a research scientist at Washington State University.
Over the past several years, engineers have made significant improvements in puffer designs, Higbee said.
"In the past, we used to have problems with 15 to 20 percent of the units. Now we're down to the 1 to 3 percent range. They've become very reliable," Higbee said.
Bigbee began his work with puffers at Paramount in 2002 and got them registered for commercial use in 2007.
Originally, Paramount began working with the puffers on small test plots.
In 2007, at one of the sites, Paramount averaged 10 percent damage using three insecticide sprays a year. Over the past three years, damage has been half a percent with only one spray, Higbee said.
On small plots, Higbee was able to get the same results with puffers as he did with insecticides -- about a 50 to 60 percent reduction in worm populations.
"When we started using it on bigger acreages, we found it getting even more effective," Higbee said.
Higbee found that putting puffers about 150 feet apart, starting from within 75 feet of the edge of the orchard, works well.
There are a few drawbacks to mating disruption, though. Even though it prevents females from getting mates, there's no way to prevent mated females from other fields from flying into the fields.
"You have to look at what other kinds of pressures are around you," and spray accordingly, Higbee said.