Research Continued from Page 13
pepper weevils, Kund said. Weather definitelyaffectspest pressure, Kund said. “Thisyear, forwhatever reason, I’veseen a lot of spider mites out in my field,” he said. “It’s hot and it’s dry, and spidermites like those conditions.” With the fluctuation of insect pressure year to year, growers have to adjust their programs accordingly, Kund said. It’s important for pest control advisors and growers to get into the field and identi- fy potential problems early, he added. Trapping can help with early identifica- tion of pests. Kund has used some pheromone traps for pepper weevil as more of an identifi- cation tool. “It kind of gives you a good idea of what’s going on in the field,” he said, “and it tells growers when they start to see pepper weevil that they need to treat now.” There are pheromone traps andmating disruptionpheromones for the lepidopter- ans. Placed in the field, pheromone traps confuse the males so they can’t find the females tomate. “That really disrupts the whole repro- duction process,” Kund said. (Kathy Coatne y i s a repor t e r in Bend, Oregon. She may be contacted at kacoatney@gmail.com.)
populations, Kund added. “Youcanactuallyget secondarypest in- festations,” he said. For instance, spraying pyrethroids weekly andnot rotatingwithother chemi- cals could result inahuge leafminer prob- lemat the end of the year. “I’ve seen fieldswhere the leafminer lar- vae are literally falling off of the leaves of a plant,” Kund said. That creates a disastrous situation for growers, he said,which iswhyan IPMpro- gram is so important. That was the approach fosteredby John Trumble: helping growers profit while us- ing safer pest control products in rotation withvariedchemical applications toguard against resistance building. Kund’s program tests a newproduct for a year. Then it is evaluated on howwell it worked. If it is effective for a particular in- sect complex, it will be incorporated into an IPM program and rotated with other chemicals, Kund said. Another portion of the program in- cludes an organic rotation in which researchers use only registered prod- ucts from the Organic Materials Review Institute,Kundexplained. Thesearemuch softer products and they may need to be useda littlemore often, depending on the pest pressure, he added.
Pepper weevils, such as the one above, pose a major threat to peppers. Researchers say they need to be treated early or their larvae will penetrate peppers, causing significant internal damage.
Pepper weevils, for example, can do a lot of damage, so it’s important to treat them early because they’re so invasive and the larvae do so much damage to the inside of the fruit. “That’s one where conventional mate- rials are kindof important touse earlyon,” Kund said. Organic growers could use a pyrethrin for pepper weevils, not to be confused with a pyrethroid. Pyrethroids are a syn- thetic material, whereas pyrethrins are taken from a plant extract. Pyrethrins are safe, but still have some neurotoxin ac- tivity that may provide some control for
There are also what Kund calls in-be- tween products that are biorational—a softer product. “Biorational compounds have to be rotated with something else,” he said, adding that many chemical companies are realizing their products are not stand- alone remedies. “The biorational compounds aremore effective when they’re used early,” he said. “That’s really important. If you wait until the problem is out of control, then it’s too late.” He said more conventional products will have to be used to control the pest.
Pests Continued from Page 9
Sacramento Valley locations weekly to help growers anticipate pest popu- lation increases. “It’s been a very good year for army- worms,” he said. Growers also have had more success controlling rice blast this year, apparently inpart becausemoregrowers areplanting themedium-grainvarietyM-210, which is resistant to the disease. Espino said resistant varieties and ni- trogen management are important in controlling riceblast, a fungal disease that survives on rice straw.When severe, it can kill young rice plants. Aggregate sheath spot and stem rot are twoother diseases that areusuallypresent at some level inmost rice fields. “Alot of thishas todowiththebuildupof inoculum,becausewehaven’tburned(rice straw) inquite a fewyears,” Espino said. The first step inmanaging thesediseases is to reduce the carry-over inoculumby re- movingordestroyingcropresidueor—inthe caseofstemrot—byusingresistantvarieties. Stem rot can be made worse in fields with stands that are too densely planted. Fungicides canbeeffectiveagainst both of thesediseases. But carefulmonitoring is needed to get there in time and be confi- dent theapplicationwill beworth thecost, Espino said. ( Bo b J o hn s o n i s a r e p o r t e r i n Sacramento. He may be contacted at bjohn11135@gmail.com.)
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14 Ag Alert September 15, 2021
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