California pest control advisors (PCAs) and growers have a well-stocked arsenal when it comes to miticide choices. Ironically, this season the mites sensed it and decided there was no point in even showing up.
“It’s been pretty light this year, although we’re starting to see some pressure,” says Thad Stephen, independent PCA who consults in the Willows/Maxwell area of California. “It’s most noticeable in young almonds. The more mature orchards are not as susceptible, and the weather this season has been near ideal so the trees are not under as much stress as they’ve been the last couple of years.”
One miticide application has pretty much held any pressure that existed all season, according to Stephen. “I put out Zeal on cotton, almonds and walnuts and it’s worked extremely well,” he says. “It’s nice to have so many options now. With Zeal, Oberon, Envidor, Onager and Agri-Mek and some of the others, we have a lot of options for a good rotational program. We’re starting to see resistance in some of the older products such as Comite and Omite. Now that we have alternatives, we can minimize that issue.”
Another luxury of having so many alternatives is the ability to pick and choose a miticide that fits a particular window. David Haviland, University of California Cooperative Extension Kern County farm advisor, has worked extensively with miticides to evaluate how to best utilize them in a given time frame.
“I sincerely hope the days of just spraying something because there might be a problem are over,” he says. “We’ve got enough materials now that we can be a lot more judicial in what we use and when we use it.”
With multiple new miticides registered in California in trees, vines and row crops over the past couple of years, PCAs and growers can be choosy, according to Haviland. Early and mid-season choices should focus on the goal of preserving beneficials and predatory mites as well as knocking down initial populations, he says.
If handled judiciously during the early part of the season, mid to late-season miticide options can continue to keep populations suppressed with minimal intervention. Agri-Mek is often the product of choice during the early part of the season as a preventative in tree crops, as is Zephyr in cotton, especially since they are relatively easy on beneficials. However, resistance concerns in some areas — particularly the San Joaquin Valley — are prompting PCAs to consider other choices.
Additionally, preventative measures are just dollars down the drain if nothing shows up. If mites don’t materialize early in the season, which was mostly the case this year, some of the newer chemistries can be utilized later as mites begin to build to a threshold.
“Three new growth regulators, Zeal, Envidor and Onager have an excellent fit during the middle portions of the season in almonds and other tree crops,” Haviland says. “The same is true for Zeal and Oberon in mid to late season cotton, even by air. “These are not so much knock-down products to use to put out a mite fire, but fit best during that middle part of the season when mites are just beginning to build, and there is still enough season left where a decent residual control is still needed. It is best when used with low threshold numbers of mites, but can still be effective later than that in some cases.”
Many of the newer chemistries require time to work which tends to make growers nervous. “A product like Zeal doesn’t knock down a mite population instantly,” Stephen says. “You can spray it at low thresholds and you may see a little webbing later on, but the eggs are pretty much destroyed. You have to be more patient with these new materials, but they are very effective.”
Scouting has become more important in mite management as a result. “Products such as Envidor and Zeal are best when mite populations are low and building,” Haviland says. “Because they don’t have quick knock-down, it’s important to apply these types of products at the appropriate threshold timing. They will still work under heavy mite infestations, but not as effectively as if they are applied at early threshold levels. If mite populations are a little higher, or show up close to harvest where pre-harvest intervals become limiting, newer contact miticides such as Fujimite, Acramite, Desperado and Kanemite are added options to the old standbys."
With a literal buffet of effective miticides to choose from, PCAs and growers are in a premier position to manage mites more effectively than ever before. As evidenced this season, a good mite management strategy doesn’t necessarily mean throwing the book at them before a problem materializes. Growers who watched and waited kept a few more dollars in the bank.