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Grower survey examines navel orangeworm strategy

USDA ARS TNFP1021-ARS-now.jpg
A navel orangeworm larva. This pest is the number-one insect enemy of almonds.
UC disseminated the questions in late summer and are now tabulating the results.

Knowledge is a two-way street — questions asked, questions answered, and all participants walk away better informed.

That’s the purpose of the 2021 Navel Orangeworm Program Survey to growers, disseminated in late summer and now being tabulated for publication. Phoebe Gordon, UC Cooperative Extension in Madera and Merced Counties and entomology specialist at Riverside, Houston Wilson, are project coordinators.

“This is kind of a needs assessment-type survey where we gathered information on what growers were doing as well as any barriers to using the four standard NOW tools [sanitation, pesticides, sprays, and mating disruption],” said Gordon.  “This is grower-given information versus the usual management implications.”

Response was positive.  “We went to seven different grower gatherings and way more than 50% of attendees voluntarily participated,” said Gordon, noting the exchange of data wasn’t one-sided: “I learned some stuff as an extension person, so the exchange of information was a two-way street.”

Although the accumulated data is still being sorted and tabulated, orchard sanitation appears to be ranking at the top of the items of concern.  “We thought the biggest turn-off issue would be the cost of sanitation, but the most important barrier to getting trees sanitized is turning out to be the ability to get into the orchard itself," Gordon said.

“Initial input started coming in by early 2020, about the time the COVID pandemic stopped us from attending some meetings in the southern San Joaquin Valley, so it may be a bit more skewed towards higher rainfall areas and may require some more research, but certain cover crops apparently allow for better access.  Heavier shakers had trouble navigating unstable soil, so orchard access was one expressed issue.”

Most sanitized annually

Initial tabulations showed that 70% of respondents sanitized every year despite the difficulties encountered and the most recent costs of about $200 an acre using one’s own equipment (or greater if custom harvesters are employed).

So once all the numbers have been crunched and the document prepared, who benefits from the results?

“This is a needs-assessment-type-thing rather than a toolbox for growers to use,” Gordon said.  “We’ll take the results and work them into our extension educational programs to more specifically address contemporary needs of growers.  There are generalized things that growers need to hear, but there are also things we advisors need to know, like if growers are struggling with specific problems.  This survey will give us a broad-brush overview of those problems.”

Referring to the sanitation issue, one of the questions asked of growers involved the effectiveness of sanitation protocol and whether or not sanitation should be implemented, or if they lacked efficacy versus effort.  Less than 10% of the respondents said they didn’t think the efforts could be called effective.

“So if I’m giving an extension talk, I’m not going to go out and tell folks this is why they need to do it because clearly everyone says they know they need to sanitize.  Instead, I’ll discuss the benefits of cover cropping and getting into the orchard during the winter.  That’s the whole reason for the survey, to see what actual grower needs are.”

Current information is invaluable in formulating current plans to solve current problems, but will support be there to implement today’s changing data?  “I certainly hope so,” she said.  “I know ag engineers are working on some of the concerns and what might be needed to improve things.”

The California Department of Food and Agriculture (Plant Health & Pest Prevention Services) is hoping the survey results will help in the development of new tools to detect and control NOW in tree nut crops including sterile insect technique (SIT), an environmentally friendly method of pest control involving the sterilization of a target pest.

CDFA reports current control methods can cost more than $400 per acre, “yet can still result in unacceptable levels of damage.”

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