Navel Orangeworm Sprays Tough to Target
By Patrick Cavanaugh, Farm News Director
Naval orangeworm is the number one pest in almonds and pistachios, and there’s a lot of research going on to find ways to manage this pest. One important strategy is timely sprays, but Joel Siegel, a research entomologist with USDA Ag Research Service in Parlier, CA, said that it’s tough to get that spray on target.
“Spraying for naval orangeworm is learning to live with loss. Many years ago, my professor told me to assume that 90 percent of what you put out never goes where you want it to go. I didn’t know that he was being an optimist when he told me that,” he said.
To confirm this, Siegel set up a controlled experiment sponsored by DuPont. “Using the best setup of spray rigs at two miles per hour, we’re basically getting 10 percent of what we calculated in the tank was actually getting on the nut,” he said. “Then if you add the difficulty of saying, you want to get it in the suture on an early split almond, you’re probably getting about two percent of what’s in your tank actually on that suture zone, so you’re dealing with a 98 percent loss.”
Siegel said the spray is getting in the tree, but not on the nut or the suture of the nut. “I’m talking about just getting on target. It’s getting on the leaves, it’s getting on the bark, it might be getting on the ground.”
Siegel noted that it’s actually better to spray at night, when the naval orange worm adults are flying. “That way, some of the drift can actually contact the adults. The other advantage of night spraying is that the humidity is higher, so you’re not getting that loss of having the droplets evaporate.”