California Pest Management Under Constant Challenge
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When it comes to agriculture and pest management challenges in California, Jim Farrar is the man to go to for answers. As the University of California, Davis director of the state's Integrated Pest Management efforts, he knows what the myriad pests and insects are and how they're being managed.
"How effectively we're fighting that battle is a tough question to answer," he admits. "Campus-based researchers and cooperative extension specialists in the field are always looking for what we can find solutions to. The biggest concern in pest management is keeping up with problems that change along with changes in climate, regulations, and production practices.
Limited pest management solutions
"As we learn more about risks associated with pesticides, the regulatory environment changes and all that means we need to keep developing new tactics and new programs to manage pests. One of our biggest challenges is just trying to keep up with those changes."
Farrar gives his IPM group a passing grade for its efforts involving the multi-billion-dollar ag industry, although he laments a lack of people and dollars to come up with new ways to do battle.
"Scientific illiteracy scares me because it impacts so many things we do. We come up with so many ways to manage pests that are not understood or acceptable by the public and that limits our ability to respond because response is who we are and what we do. We're a science-based organization trying to address problems with evidence."
Because much of California involves the growing of specialty crops, it has its own separate pesticide registration protocol. "So many pesticide tools come on the market, but California typically lacks the ability to use some of these new technologies because of our independent registration process," admits Fresno County Farm Bureau CEO Ryan Andersen.
"The number of acres involved in many of these crops is minor, so manufacturers often don't chase those markets until the issue becomes problematic. And the state is constantly trying to eliminate some of the former tools we had at our disposal without necessarily having new tools to take their place.
"Pest management is a massive issue because we have some significant bugs we have to deal with like ACP (Asian Citrus Psyllid) in the citrus industry, sharpshooters in the grape trade, and navel orangeworm in the almond group. These industries are collectively trying to figure out how to work collaboratively instead of approaching pest management single-handedly. We're hopeful we can continue to have the available crop tools to go after these critters on a more holistic, rather than an individualized, approach."
Challenge: vine mealybug
A perfect example is that of the vine mealybug, first introduced into the Coachella Valley in the early 1990s and quickly spreading to distant grape-growing regions from the San Joaquin Valley through Monterey. Mealybug infestations can severely impact both quality and yield because wounds inflicted during feeding can cause contamination, sooty mold, and fruit-rotting pathogens.
For more than two decades, David Haviland has been boots-on-the-ground-bug-expert in Kern (Kings and Tulare) County, as a University of California Cooperative Extension entomologist responsible for over 100 commodities worth about $18 billion a year. Notes Haviland: "At a statewide level, vine mealybug has become the single most important and impactful insect within the grape industry.
There are multiple species of mealybugs in the state, but the big concern is the vine mealybug, he explains. The pest has spread beyond the Coachella Valley on equipment and planting materials. "It may not be in all vineyards, but it's in at least one vineyard in every part of the state, and in some places like Kern County, it's ubiquitous," he adds.
The big issue here is fruit contamination, especially with table grape growers who have a low tolerance for the pest. For wine grape growers, particularly those in the North Coast, vine mealybug vectors the grapevine leaf roll virus that impacts fruit quality. And for organic growers limited to just biocontrol and mating disruption, there is a significant loss every year.
"At a statewide level, vine mealybug has become the single most important and impactful insect within the grape industry."
"I'm not aware of a single case of total eradication, so we've moved on to managing the problem, says Haviland. “In the past, there were times where mealybugs were completely out of control, causing devastating impacts, and we don't really see that anymore, just isolated cases where the virus is significant. Still, we're far from being in the clear on this one."
New mealybug control available
One of the latest responses is Sequoia® CA insecticide from Corteva Agriscience. "It's labeled for mealybug control in grapes, and grower response throughout the state has been very positive, as more effective mealybug tools are needed" said Jeffrey Pacheco, marketing development specialist, Corteva Agriscience.
"This is newly registered in California as a selective insecticide which should fit well in an IPM program. There are other products that have been used for a decade or so that are not performing as they used to as the mealybug pressure has become worse and more widespread. We're losing tools to control and manage this pest, and this is a unique mode of action — subgroup 4C (sulfoximine) — that growers can utilize in rotational programs to manage mealybugs throughout the season."
UCCE's Haviland sums up statewide pest and insect management efforts as an ongoing and ever-changing battle where there have been wins in some cases and in others, not so much.
"We're losing tools to control and manage this pest, and this is a unique mode of action that growers can utilize in rotational programs to manage mealybugs throughout the season."
"When it comes to long-term sustainable management, every pest shows up somewhere in that process as we figure out what they are, what they're doing, and try to come up with responses to their arrival."
This article developed by Farm Progress exclusively for Corteva Agriscience.
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