Cling peach growers use new methods
A two-year demonstration project showed canning peach growers that using reduced-risk pest management methods against oriental fruit moth, peach twig borer, and obliquebanded leafroller can achieve the control they need while reducing impact on the environment.
Project leaders recruited San Joaquin Valley growers who were willing to use newer, more environmentally friendly ways to manage important pests in their cling peach orchards. IPM methods—including mating disruption and reduced-risk insecticides as needed plus augmentation of oriental fruit moth parasites—successfully prevented these three pests from causing damage in the demonstration orchards.
The reduced-risk methods were compared to growers’ commonly used program where they sprayed pyrethroid insecticides for the same pests. Regulators have targeted organophosphate and pyrethroid insecticides for elimination or severe reduction because of their harmful effects on water quality and nontarget organisms.
The project also demonstrated a way to augment biological control of peach pests to further reduce pesticide use. Researchers released the parasitoid Macrocentrus ancylivorus and planted commercial sunflowers in or near the orchards to help breed sunflower moths that can provide a bridge for parasitoid survival from one season to the next. Macrocentrus parasitized sunflower moth at rates ranging from 4 to 10%, supporting long-term establishment of Macrocentrus in the orchards.
The project leaders—UC Cooperative Extension Specialist Marshall Johnson, UC IPM Advisor Walt Bentley, UCCE Farm Advisors Roger Duncan and Maxwell Norton, and Research Associates Andrew Molinar and Hannah Nadel—recruited canning peach growers who were willing to try reducing their use of organophosphates and pyrethroids.
In 2009 and 2010, project leaders and UCCE farm advisors taught growers and their pest control advisers to integrate reduced-risk insecticides such as diflubenzuron (Dimilin), methoxyfenozide (Intrepid), spinetorum (Delegate), and spinosad (Entrust) in combination with mating disruption, a technique that uses a female sex pheromone to confuse male moths and prevent or delay mating. These products are either nontoxic or only mildly toxic to the oriental fruit moth parasite Macrocentrus ancylivorus.
Four of the six cooperating growers never had used mating disruption or a newly available mating disruption device, but in the trials all of them had success using it on at least 10 acres, with one adopting the technique over his entire cling peach acreage. Local UCCE farm advisors supported growers’ efforts with one-on-one training sessions and frequent advice.
A particularly noteworthy success was achieved by Ceres growers Scott and Sid Long, who adopted mating disruption over their entire 130 acres of canning peach varieties. In 2008, the Longs’ trees suffered severe oriental fruit moth damage, even after up to five treatments with phosmet and esfenvalerate, organophosphate and pyrethroid insecticides. Duncan worked closely with these growers and their pest control adviser, and using only mating disruption, the growers recorded no damage in 2009 and 2010.
"Our cooperation with Roger Duncan, Walt and Marshall Johnson resulted in eliminating a severe Oriental fruit moth fruit infestation problem experienced the year prior to the project. We instituted a mating disruption program and incorporated a single reduced risk spray, " Scott Long said. "This eliminated the need for multiple organophosphate and pyrethroid sprays used previously. We have continued this reduced program for the second year with no arthropod problems developing."
In three locations, the project team tried adding biological control to the mating disruption program. Growers released the parasitoid Macrocentrus ancylivorus that can kill pest larvae. Macrocentrus can survive over the winter after parasitizing sunflower moth larvae, so the cooperators also planted sunflowers in or near the orchards to help breed sunflower moths. The parasite does not overwinter on oriental fruit moth.
Researchers believe the mating disruption program controlled the peach pests so well it explained why they could not find pest larvae to see how well the Macrocentrus worked. Researchers did find Macrocentrus in sunflower moth larvae in infested sunflower heads next to the orchards, showing that the parasitoid had become established. Commercial sunflowers host Macrocentrus in much higher numbers than wild sunflowers do, but Bentley anticipates that the releases will perform similarly in wild sunflowers, which also could be important in establishing these biological control agents.
Although the effectiveness of both Macrocentrus releases and using sunflowers to enhance the numbers in the demonstration orchards was not conclusive, a survey showed that 80 to 90% of the people who attended in-field workshops in Stanislaus and Merced counties would consider using the technique.
A California Department of Pesticide Regulation Pest Management Alliance grant funded the Canning Peach Pest Management Alliance for the northern San Joaquin Valley. The alliance included the project team leaders, six growers, and five pest control advisors. Dan Bean, manager of the Colorado Department of Agriculture, Division of Biological Control in Palisade, Colo., supplied the Macrocentrus parasitoids, and industry partners Del Monte Inc. and Pacific Biocontrol Corp. also collaborated on the project.
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