As hull split approached in June, University of California IPM advisor Kris Tollerup is warning growers this month of potential navel orangeworm presence above and beyond 2017.
“How high is the navel orangeworm pressure this year?” Tollerup asked a roomful of almond growers in Selma. “Very high, right?”
“Up north, I hear people are capturing tons of moths...and tons of females,” Tollerup said. “I don’t want to be the bearer of bad news but we’re very likely to have another rough year this year,” Tollerup said.
Blue Diamond officials said the same.
“2018 is up here,” said Ben Goudie, membership development manager for Blue Diamond, pointing to the ceiling.
“What are your PCA’s telling you about navel orangeworm in your traps this year?” asked Goudie.
“It’s high,” a grower confirmed.
Sanitation issues are a big part of the equation for a second year in a row, Tollerup said.
“Mating disruption is probably the way we’re going to have to go, even though it’s no silver bullet,” Tollerup said.
He said its very important to establish a biofix, which UCANR defines as “an identifiable point in the life cycle of the pest at which you can begin degree-day accumulation or take a management action.”
Peterson traps do a good job of catching female moths, Tollerup said.
Tollerup also recommended the UC’s degree days models to estimate navel orangeworm activity: “This is extremely helpful for timing applications,” he told growers.
Goudie told growers that if the weather holds on its current course, Blue Diamond’s estimate is that July 8 or July 9 will mark the beginning of hull split in many parts of the state, depending on varieties.
“To me, every orchard is going to need a hull split spray (for navel orangeworm),” Tollerup said. “If you’re going to do a two-spray program, you want to go early, after the beginning of hull split.”
One important consideration for growers is that hull split begins at the top of the tree first, said Mel Machado, director of member relations for Blue Diamond.
“Maybe an aerial is the first spray,” he said.
Machado said that might help with navel orangeworm damage after a challenging 2017 in which he saw growers who usually have two percent damage levels shoot up to the eight to 12 percent range.
Ants shouldn’t be ignored, Tollerup said, pointing out that it’s currently “prime time for ant control.”
“Navel orangeworm and ants are different problems, but if you’re on the bubble, ants can put you over the edge in rejects and damage,” said Goudie.
Aerial sprays and a two-spray approach at hull split may help growers, but at the end of the day, Machado said he reminds growers of the age-old truth of navel orangeworm.
“What’s the primary method of controlling navel orangeworm?” Machado asked.
“Sanitation,” a grower said.
“And the second?”
“Sanitation.”
“And the third?”
“Sanitation!”
It was the only time all day, and maybe all season, that growers got a chuckle out of navel orangeworm.
Now, with hull split approaching, the fight is on.
Here are some links to previous navel orangeworm posts for tree nut growers:
- Navel orangeworm mating disruption basics for pistachio growers: The how, the why, and the where
- Evolving pest: UC addresses navel orangeworm's growing threat