Fruits & Vegetables A SPECIAL GROWERS’ REPORT OF AG ALERT ® CALIFORNIA
New tools take aim at controlling strawberry pests By Bob Johnson Strawberry growers in the Central Coast are headed toward a zero-tolerance policy on lygus bugs, the most destructive insect pest in the crop. When the bugs feed on the seeds, they cause misshapen fruit that is unfit for market. Even slight damage can lead to hidden but substantial yield loss. The yield difference came because berries grew larger when lygus bugs were better controlled and the insects’ feeding was reduced. The berries in experimental plots aver- aged 22 grams, while those in nearby untreated plots averaged 16 grams. Research conducted by the University of California tested new insecticides for controlling lygus bugs, a top pest for strawberries. Additional research also explored whether beneficial insects, fungi and bacteria can help manage spotted wing drosophila, which has developed resistance to widely used insecticides.
“When seeds are missing, the fruits are smaller,” Bolda said. “The near total elimination of lygus makes the fruit larger. There was a 40% difference in yield between the material that controlled lygus and the untreated control.” Researchers also monitored beneficial insect populations as part of the trials. “After the spray, there were significantly fewer spiders and minute pirate bugs,” Bolda said. “After the spray, there is an impact, but the population recovers.” Bolda said some currently widely used materials for treating lygus bugs, including Malathion and Mustang Maxx, demonstrated detrimental impacts on beneficial insects in trials. He said new materials expected to be registered soon aim to protect beneficials while providing control of lygus bugs throughout the strawberry growing season. Avaunt eVo, an insect-control product used on a variety of specialty crops, should be registered by the end of the year, he noted. Also in the registration process is the insecticide Sefina. In addition, Syngenta is evaluating another new lygus material as part of the registration process for its
“When lygus feed, they are destroying the embryo,” said Mark Bolda, University of California Cooperative Extension farm advisor based in Watsonville. “As slight as the damage may be, it can still cause a significant loss in yield.” Bolda conducted research trials in 2021 and 2022 on new materials for controlling lygus bugs in strawberries. He discussed the findings at the 2024 Strawberry Production Research Meeting in Watsonville. The event also provided research insights on using beneficial insects to target another strawberry pest, spotted wing drosophila. The field trials on lygus bug remedies, which Bolda conducted in partnership with the crop-protection company Syngenta, revealed the effectiveness of an experimental insec- ticide in curbing yield losses. Strawberries treated with ISM-555, which contains a new insecticide, Plinazolin, yielded an average of 2,679 boxes an acre. Plots treated with the pyrethroid Mustang Maxx yielded 1,874 boxes an acre. Untreated plots produced 1,685 boxes an acre, according to trial results.
See PESTS, Page 7
6 Ag Alert April 17, 2024
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