Issue link: http://read.dmtmag.com/i/54939
Growers fear loss of antibiotics Organic producers have few tools to control fireblight. by Richard Lehnert don't use synthetic substances and don't cure a problem until you know you have that problem. Control of fire- blight with antibiotics goes against those principles. Antibiotics are synthetic, and they work best when applied preventatively, not as a curative. During a session on organic apple production during T the Great Lakes Fruit, Vegetable, and Farm Market Expo in Grand Rapids, Michigan, last December, a roundtable discussion focused on fireblight control. Several partici- pants expressed frustration over the National Organic Standards Board's push for elimination of antibiotic use within a short time frame. Involved in the roundtable were Jim Koan, grower and owner of Al-Mar Orchards in Flushing, Michigan; Dr. David Granatstein, with the Washington State University Tree Fruit Research and Extension Center; Dr. George Sundin, Michigan State University plant pathologist; and Dr. Matt Grieshop, entomologist and head of the Organic Pest Management Laboratory at Michigan State University. he shape of organic apple production in the future could well hinge on decisions made in the next few years about the continued use of antibiotics for control of fireblight. Two key tenets of organic production are, Koan complained about the "activist members" of the NOSB, who "don't understand and don't have to live with the consequences of their decisions. "I'd be out of business without antibiotics for fireblight control," he said. Both tetracycline and streptomycin were subject to sunset provisions that are slated to become effective October 21 of this year and were subject for discussion and recommendations last year. Koan advocated reform of NOSB, which is made up 15 people appointed to represent various interests. Four of them are growers, while six represent consumer or environmental interests. Koan said the board needed a technical review committee to address technical issues. Granatstein agreed the board "reviews things they don't understand" and that it sometimes appears that the blind are leading the blind. Sundin said, "If you lose these antibiotics, you'll stay in business until the next epidemic hits." Last April, the Organic Tree Fruit Association, which speaks on behalf of eastern growers, took a position on the use of streptomycin in apple production. Strepto- mycin seems to work best in eastern and midwestern orchards, while western growers find tetracycline more effective. OFTA stated in a position paper that the best use of streptomycin is to apply it on the most susceptible blocks after a confirmed infection. Expo panel members said that is not an effective approach. Conventional growers apply antibiotics when environmental conditions are conducive to development of fireblight rather than seeking to cure it after infection has been confirmed. Everyone on the panel agreed that the goals of NOSB and of organic producers are laudatory: • Plant resistant varieties: Resistant varieties, how- ever, may not fill consumer demand. Red Delicious is the most fireblight-resistant variety, but it is the least wanted by organic consumers, Granatstein said. NOSB emphasises genetics. Resistant apple rootstocks would mitigate the damage caused by fireblight, since only the scion would be damaged and the rootstock could be topworked. But resistant rootstocks are not available in quantity and may not be for years. • Adopt alternative controls: "A lot of work is being done to find nonantibiotic controls," Granatstein said, but few are registered or proven effective. Serenade Max (Bacillus subtilis) has worked in Michigan. The consensus seemed to be: Don't rush to get rid of antibiotics until more effective control methods are in place and working. • "Savings in hand thinning time and/or increases in fruit sizes resulted in a net positive impact of $123/ha to $1368/ha compared with hand thinning alone." - Baugher, Schupp, et al. Mechanical string thinner reduces crop load in various stages of bloom development in peach and nectarine trees. HORTSCIENCE 45(9): 1327-1331, 2010 Manufactured by; 4509 Bartlett Rd. Beamsville, ON Canada www.bartlett.ca Dealer in South Western US: P.O. BOX 550 Fowler, CA 93625 105 N Spokane Rd. Moxee, WA 98936 Dealer in North Western US; 559.834.1588 www.calagenterprisesinc.com 1.800.827.0972 www.bluelinemfg.com 22 FEBRUARY 15, 2012 GOOD FRUIT GROWER www.goodfruit.com 905.563.8261