Issue link: http://read.dmtmag.com/i/466321
36 MARCH 1, 2015 GOOD FRUIT GROWER www.goodfruit.com E ntomologists John Wise and Matt Grieshop are in hearty agreement on one thing: There's got to be a better way of managing pests than hauling heavy sprayers carrying hundreds of gallons of tank mix up and down orchard alleys several times each growing season, blasting away. "Studies have shown that from 29 to 56 percent of what we spray is actually deposited on the tree," Michigan State University entomologist Wise said during a presentation to fruit growers during the Great Lakes Fruit, Vegetable, and Farm Market Expo in Grand Rapids in December. That's kind of an insult to growers' pocketbooks as well as to the environment, when so much expensive pesticide winds up on the ground or drifts away from the target. "Conventional airblast sprayers are ineffi cient deliv- ery systems," he said. Wise and Grieshop did a tag team presentation, each talking about his own research to develop new ways for growers to control pests in the future. Wise is taking some pointers from the shade tree and ornamental industry, where trunk injection is a pre- ferred method for protecting trees in public areas like parks. Trunk injection is used when a tree owner is trying to save high-value trees from attack by invasive species like Japanese beetles, emerald ash borer, the elm bark beetle that carries Dutch elm disease, or from diseases like sudden oak death, oak wilt, apple scab, and Phytophthora root rots. Pesticide injected into a tree's trunk moves through its vascular system, providing protection, using greatly reduced rates of active ingredient and no exposure to the environment. Grieshop, who heads the organic pest management program at Michigan State University, is working on a number of non-airblast-sprayer techniques, including permanent orchard irrigation-like installations known as the Solid Set Canopy Delivery System. Grieshop and his colleagues have also developed an attract-and-kill lure for Oriental fruit moth and codling moth and are working on Japanese beetles and lea- frollers. Insects are attracted by pheromones and then killed by insecticide as they contact the device trying to get to the pheromone. Grieshop also works with waxes and other kinds of baits and with mating disruption. As Wise looks at history, spray equipment, spray materials, and orchards evolved in harmony for about 50 years until near the end of the 20th century. "It was an amazing century," he said. "The discovery of synthetic nerve-active materials had a huge impact on agriculture." Since they were relatively inexpensive and broad spec- trum, and there was minimal concern about environ- mental impact, airblast sprayers provided good coverage. In recent years, with the use of smaller trees, sprayer noz- zles and fans have been redesigned to be more effi cient. But as the 21st century approached, the playing fi eld changed. The Endangered Species Protection Act, the Clean Water Act, and, especially, the Food Quality Protection Act resulted in many good pesticides being challenged, Wise said. The new measure wasn't whether products were effective, but whether they were safe for workers and nontarget benefi cial insects, such as honeybees. New products that replaced old ones like Guthion (azinphos-methyl) work differently, Wise said. While Guthion killed eggs, larvae, and adults on contact, the newer products often have no contact activity and must be ingested, or work in more subtle ways by interrupting key insect processes like molting, deterring egg laying, repelling without killing, or discouraging feeding. Some work by inducing resistance in the host plant. Fermentation-created biopesticides, like Bt (Bacillus thuringiensis) and spinosyns and others, are exciting, Wise said. "Many of them are really good," he added. Some of the botanical e x t r a c t s — p y r e t h r i n s , sabadilla, and neem—are being used effectively, he said. While human medi- cine has been developing patches to replace nee- dles, and row crop farm- ers have been using seed treatments that provide protection while reducing rates of active ingredient by 90 percent, the orchard industries have been refi ning the airblast sprayer but making no quantum leaps. "What about us?" Wise asks. Trunk injection Wise uses tools already developed by the shade tree industry to inject fungicides or insecticides into the tree's xylem nutrient delivery system. The modern orchard design—many smaller trees—makes the treatment process less easy than it would have been years ago. Treatment is labor intensive. He began testing the concept in 2010, just to see if it might work, but he has worked with just a few of the many pesticides. He fi nds the method does well at pro- tecting trees from insects that attack foliage. Insecticides seem to move better inside the tree than fungicides, but he reports "promising" results against apple scab. One treatment can be effective for an entire year and sometimes even into the second year. 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