Advances in IPM through extension research programs have led to better insect pest control and more uniform fruit for consumers.
PHOTOS BY SALLY COLBY
Research in tree fruit production has provided growers with benefits from new cultivars and highly efficient growing systems to labor and energy savings. Much of the work has been done through the combined efforts of growers working with cooperative extensions. However, cuts in funding from many state programs threaten to limit or eliminate ongoing research.
Dr. Larry Hull, Penn State University entomologist, describes the development of integrated pest management (IPM) and the challenges he and other researchers have faced over the years. Hull, who has spent more than 35 years working with deciduous fruit, says that although IPM for tree fruits has improved greatly, one of the biggest challenges for growers is insect pests.
“You know the big ones – codling moth, oriental fruit moth, leaf roller species, plum curculio, aphids,” he said. “We’ve seen outbreaks of the woolly apple aphid, European apple sawfly, leafhoppers, leaf miners, spider mites and scale. And I see apple maggot as a potential pest issue in the near future.”
Hull says that IPM for tree fruits has developed greatly over the past 35 years. “We’ve looked at the complexity of the agro-ecosystem, pest biology and behavior. We’ve looked at all the natural enemies we could find and learned how to use them. We’ve developed economic thresholds and injury levels, looked at cultural controls and studied insecticides and try to use them in an ecologically friendly manner that doesn’t kill all the predators. We’ve also used pheromone mating disruption in many orchards.” However, new insect pests and the loss of labeled products mean there’s more work to do.
Hull says that determining criteria for inclusion of new chemicals or biologicals in an IPM program keeps entomologists busy. “We look at the effectiveness against various stages of pests, determine the minimum dosages for keeping pests below specific economic injury levels and determine phytotoxic effects to fruit or foliage. We also have to figure out if natural enemies will survive at pest-effective dosages, and the level of impact on the food sources of natural enemies.”
One IPM development Hull worked on is alternate row middle spraying (ARM), a practice that began in the late 1950s when New York growers used the technique to control early season apple scab. “It gained more popularity as tree density increased and we planted smaller and smaller trees,” said Hull. “There’s better use of time and equipment and reduction in environmental pollution.” ARM also increases the survivability of predators and natural enemies because many products can be used at reduced rates. Hull says that the primary reason for ARM failure is lack of adequate coverage on the inside of the tree and on the opposite side of the tree.
Despite IPM improvements, Hull says that the 1970s saw a serious pest challenge with the tufted apple bud moth (TABM). “We looked at mating disruption, ground cover management and growth regulators to control TABM and conserve our IPM,” said Hull. “Can insecticide resistance management for TABM coexist with integrated mite management in orchards? Yes, to varying degrees, but success depended on the likelihood that new chemistries would be developed.”
Insects that change their habits present another IPM challenge. “We’re seeing a change in codling moth emergence over the last 15 to 20 years,” said Hull. “They seem to fly much longer for each generation.” He added that an ongoing challenge for entomologists is looking at every product that growers can legally apply and determining the optimum ways to use each product. “What’s the minimum dose we can use? Are there any phytotoxic effects? What is the survival of natural enemies?”
Although growers are often a step ahead of pest damage, emerging pests and pests that travel to new territory present problems. The brown marmorated stinkbug (BMSB) has become the number one issue throughout the Northeast in 2011, and its range is spreading. Hull predicts that in 2013-2015, pest threats will include San Jose scale, European apple sawfly, red-banded leaf roller, plant bugs and apple maggot. He says that there will be increased movement of exotic pests, including spotted wing drosophila and light brown apple moth (LBAM). “We have threats heading in our direction that we have to be prepared for. But for this year, and for the next several years, the brown marmorated stinkbug is going to be one of the biggest problems.”
Advanced pest management will involve more complex selective programs along with more behavioral-based management and less insecticide-based management. “We’re doing close monitoring and development of a lure and trap for the BMSB and pheromone mating disruption for the dogwood borer,” he said. “There are more mating disruption dispenser methods coming, sprayer application mapping and some automated sprayer discharge controls.”
Hull says that future technology currently under development includes automated electronic pheromone traps, robo-scouting for insects and injury, sprayer sensing of tree canopy density and variable rate and volume of pesticide application, and pesticide mixing on sprayer.
One of the biggest issues for growers is the fallout resulting from faculty and funding cuts at land grant universities. Hull is hopeful that the role of cooperative extension will be maintained, but he predicts that the role of the private sector will expand, and growers will be relying more and more on the Internet for delivery of pest management information. “From what we know, and if we aren’t careful, we could very easily flush IPM.”
The author is a new contributor and freelance writer who farms and raises Great Pyrenees in south-central Pennsylvania. Comment or question? Visit www.farmingforumsite.com and join in the discussions.