A team of ISU researchers is investigating ways to reduce the amount of pesticides applied to apples. These crunchy red and green fruits are one of the most pesticide-intensive crops grown in the United States. In order to produce a marketable fruit, growers are forced to spray their crop with pesticides multiple times throughout the growing season, said Mark Gleason, professor of plant pathology.”Apples are sprayed periodically from late April through October. They receive more pesticides than any other crop in the U.S.,” he said.A $306,000 U.S. Department of Agriculture grant awarded in July 2000 is assisting ISU researchers in developing a system to reduce the amount of pesticides applied to apple orchards. The grant is also being used by scientists in Missouri, Illinois, Wisconsin and North Carolina. Gleason said the grant is one of several given to the research of alternative methods of pest management in orchards. The project is funded through the next three years. Gleason said researchers are currently preparing for the 2001 growing season.”Without Dr. Gleason’s work in integrated pest management, growers would only have traditional pest control methods,” said Gail Nonnecke, professor of horticulture. Scientists are working specifically with codling moth and sooty blotch/flyspeck disease. Nonnecke said other than the prevalent apple scab disease, sooty blotch/flyspeck disease and codling moth are very significant problems for apple growers. Gleason said sooty blotch/flyspeck disease causes blemishes on the exterior of the apple, but doesn’t affect the taste. Codling moth, an insect pest, is more serious with the ability to destroy a crop.These two pest-related problems greatly reduce the value of apples. Gleason said apples with sooty blotch/flyspeck disease couldn’t be marketed as fresh apples; therefore they often are sold as cider apples. Cider apples have one-third the value of fresh apples. Recent Environmental Protection Agency regulations and the development of the Food Quality Protection Act in 1996 have limited the use of pesticides by fruit growers, Gleason said.”The Food Quality Protection Act focused on people, looking at their life exposure to pesticides,” he said. “It works to limit the amount of total risks [to pesticides].” To control sooty blotch/flyspeck disease, Gleason and the team of ISU researchers are working to develop a disease-warning system, a method of reducing pesticide application through close monitoring of crop conditions.”The disease-warning system is a way to figure out when disease outbreak is high,” he said. He said the disease-warning system takes into account weather conditions and ecology of the pest when formulating a recommendation about applying pesticides. “We only want to apply pesticides when the risk is high,” Gleason said. He also said reduced pesticide application results in valuable savings to growers.”A 50-acre orchard can save $1,000 each time they don’t spray for sooty blotch/flyspeck disease,” Gleason said. He said the cost of installing a disease-warning system is relatively low in terms of the projected savings. Scientists are developing ways of reducing codling moth problems through an approach called mating disruption. This process involves the development of a synthetic sex pheromone, a communication hormone to attract the male codling moth to the female. Gleason said the pheromone would be distributed throughout the orchard, confusing the male and preventing him from locating the female. This will result in the numbers of codling moth pests diminishing due to the lack of fertilization and offspring. “We’re planning field experiments at the horticulture farm. We’ll be looking at codling moth and various versions of the disease-warning system,” he said.