Good Fruit Grower

April 15th

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Pheromones explored for psylla R Male psylla are attracted to pheromone lures. by Geraldine Warner educing pear psylla popula- tions in the spring is the key to keeping the pest in check later in the season, entomologists say, and a recently discovered pear psylla pheromone might play a role. Currently, pear growers apply pesti- cides with oil in the delayed dormant sea- son to target winterform adults as they return to orchards after spending the win- ter on other hosts. Growers also coat the trees with Surround (kaolin clay), which is somewhat repellent to the psylla and deters females from laying eggs. However, both oil and Surround need to be applied multiple times to be effective. Dr. Dave Horton, entomologist with the U.S. Department of Agriculture in Yakima, believes that it might be possible to use the pear psylla pheromone to dis- rupt mating and delay egg laying by win- terform females after they return to the orchard, as a supplement to the standard controls, although he cautions that this is all very hypothetical at the moment. He is exploring in the laboratory whether satu- ration of airspace with pheromone could affect the ability of males to rapidly find females and thus delay mating. Delays in egg laying lead to more synchrony in egg hatch, which in turn simplifies control of the developing summerform generation, Horton said. Horton and colleague Dr. Christelle Guédot began testing the pheromone in the field three years ago. The research shows that there's a period in January and February when the females are not producing the pheromone during which males are attracted to traps with pheromone lures. Once the winterform females begin producing the pheromone in March, the traps with lures become less effective in attracting males. Horton is try- ing to improve the lure by testing different dosages of the pheromone and different types of traps. Horton and Guédot have also studied Syngenta Inspire the summerform pear psylla and found that the competitive effects of females are less. From June through August, traps with lures consistently attract more male psylla, regardless of the psylla density. Horton said he will explore this further by tests of different pheromone dosages and will explore whether saturation with the pheromone could affect the ability of the males to find females and thus delay mating and egg laying. Unlike the pheromones of some other insects, the psylla pheromone appears only to work at close range, he said. The pheromone was isolated from the cuticle of the female insect and is not known at this time to be something she emits. Horton said that a scientist in Japan When it comes to fungicides, one star seems to stand out. The powerful broad-spectrum disease control of Inspire Super® fungicide stands out above all others. By combining a best-in-class triazole with a second highly effective fungicide, growers of pome fruit, almonds, grapes and many vegetables can depend on its superior performance. Proven across the world, it stops disease in its tracks. For power and reliability, there's no better choice than "top of the class" Inspire Super. has discovered a simple procedure to syn- thesize the pheromone, so if it does have commercial potential for controlling pear psylla, the new procedure might help keep costs down. "I would suggest that if we could find a practical purpose for this, the best oppor- tunity might be in disrupting winterform females as they're returning to the orchard," he said. "The females are not yet mated at that time of year. Growers want to push that egg laying back as far as pos- sible, and if we can saturate the orchard with enough pheromone, there might be a way of slowing mating in late winter and spring as they're returning to the orchard." Repellent Horton is also testing a psyllid repel- ©2012 Syngenta. Important: Always read and follow all bag tag and label instructions before buying or using Syngenta products. The instructions contain important conditions of sale, including limitations of warranty and remedy. All crop protection products and seed treatments may not be registered for sale or use in all states. Please check with your state or local extension service before buying or using these products. Inspire Super® , the Alliance frame, the Purpose icon and the Syngenta logo are trademarks of a Syngenta Group Company. Syngenta Customer Center: 1-866-SYNGENT(A) (796-4368). www.FarmAssist.com MW 10CC2006-Super-NB2 04/12 lent that was discovered by scientists exploring why citrus trees planted near guava trees had fewer citrus psyllids. The compound dimethyl disulphide (DMSD) identified in volatiles emitted by the guava trees was found in laboratory tests to be highly repellent to citrus psyllid. Recent trials have shown that the potato psyllid is also repelled by the compound. ISCA Technologies has manufactured a wax-based formulation called SPLAT to release DMDS. In tests in citrus, psyllids left plots that were treated with the repel- lent within three days. Horton said the DMDS disappeared within 28 days as it volatilized, but in pears, an application would only need to cover the period in 14 APRIL 15, 2012 GOOD FRUIT GROWER www.goodfruit.com

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