UC’s David Haviland talks about progress in disrupting mating navel orangeworms.
For decades scientists have been trying to produce products to emulate navel orangeworm pheromones, disrupting the pest’s mating habits. There are a handful of products on the market.
What’s the next step? Identifying how, why, and where these products work, University of California entomologist David Haviland told a crowd of pistachio growers in Visalia this week.
While Haviland didn’t have pistachio-specific data to share (that’s coming in a future study, hopefully) he had plenty of information to share from studies of almond orchards.
Haviland and his team tested four different mating disruption products using 40 acre plots. The mating disruption products were tested alongside a spraying program, not by themselves.
The average damage reduction at harvest was 46%.
“All four of these production areas basically reduced damage by about half,” Haviland said. “It’s on par with what we hear in industry, coffee shop, and these data support it.”
The products tested were:
- Puffer NOW (Suterra)
- Semios NOW (Semios)
- Isomate NOW (Pacific Biocontrol)
- Cidetrak NOW Meso (Trécé, not yet registered)
Next Haviland’s team ran economic calculations on whether mating disruption programs were worthwhile, considering yield per variety, pollinizer costs, and a sliding scale for low nonpareil damage based on Blue Diamond’s Crop Quality Schedule.
The economic gains for using mating disruption ranged between $106 and $125 per acre.
Haviland acknowledged that’s awfully close to the average costs of between $110 and $120.
But that’s not the end of the story.
Haviland and his colleague Jhalendra Rijal found that in some of the plots, navel orangeworm damage reduction was significant, cut by half or more, with crop value increases, while in triangle-shaped plots, there was no change in damage, and the program didn’t pay for itself.
Table based on presentation slides from Haviland presented in Visalia.
“I’m not cherry picking data here, we had two sites where this didn’t work,” Haviland said. “(In these cases) it doesn’t pencil out.”
The triangle shaped plots were less successful, Haviland said, because wind and geography causes the mating disruption product to blow directionally.
A large square plot can contain enough product, even with blowing, to deliver the hoped-for disruption of navel orangeworm mating.
An irregular-shaped plot such as a triangle or skinny rectangle could see benefits be blown out of the orchard where the product is deployed. Less core area is covered.
For smaller fields and triangles, Haviland advised, growers should try to work with neighbors—grab lunch with them, talk NOW, and work out a mating disruption program together.
For growers with larger plots, Haviland said mating disruption is an effective technique for dealing with navel orangeworm, when used in combination with a spraying program.
Even for smaller and more irregularly shaped plots where the economics are breakeven, Haviland said it’s still worth a grower’s time.
“If it costs the same as what you get back, is it worth it? I hear yes,” Haviland said. “From the hullers, I get hell yesses….There are a lot of reasons to use mating disruption that aren’t just the strict, dollar to dollar return.”
The reason for huller enthusiasm is that mating disruption helps cut aflatoxin levels.
Another benefit is that mating disruption means reduced risk of navel orangeworm resistance to a limited toolbox of insecticides.
One caution Haviland had for the growers: mating disruption can’t replace spraying or orchard sanitation.
“You should really be adding it to your program, not cutting back sprays to make up the cost,” Haviland said. “Don’t use mating disruption as an excuse to skimp on the last two weeks of sanitation. It can help, but it’s not going to save you.”