Researchers are working to learn more about potential alternative nematode control options that can be used in California carrot production. A screening trial was conducted in 2021 at the University of California Cooperative Extension Research Farm in Shafter. Kern County Vegetable Crops Advisor, Jaspreet Sidhu noted that root-knot nematodes present a significant challenge for carrot growers. Nematodes can cause substantial damage to roots, resulting in lower marketable yields.
“So far, we do not have any resistant varieties of carrots with resistance to root-knot nematodes. The management has relied on preplant fumigation in California,” said Sidhu. “But with the increased environmental regulations by the Department of Pesticide Regulation there are some challenges in managing root-knot nematodes in carrots.”
The new regulations for fumigants will significantly limit nematode treatments, leaving growers with limited management options. Sidhu said that any alternative nematode control options will need to be effective, economically viable, and environmentally safe. Some materials evaluated as part of the trial showed promise. “There is good potential in reducing root-knot nematodes with some products such as Nimitz. Then there is a developmental product coming from another company, and Velum was also promising in our trials,” Sidhu explained.
Detailed results from the screening trial are available through the Kern County Vegetable Crops newsletter. The three products Sidhu highlighted show potential for being viable options, but further evaluation will be needed to better understand their efficacy. Researchers will continue generating data that can help to support registration of non-fumigant nematicides for carrots.
“Hopefully we will have some of the products registered for the carrot industry soon here in California. We might be closer to getting a couple of them registered in the next year or so,” said Sidhu. “We will also keep screening other additional products so that we have a few more products to rely on in case we see resistance, or we see other issues coming up with the other products.”
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