From isnv@ars-grin.gov Thu Sep 7 00:22:38 2000 Date: Wed, 6 Sep 2000 10:09:36 -0400 From: ARS News Service To: ARS News List Subject: Planting Wheat May Help Apple Growers STORY LEAD: Planting Wheat May Help Apple Growers Manage Disease ___________________________________________ ARS News Service Agricultural Research Service, USDA Kathryn Barry Stelljes, (510) 559-6069, kbstelljes@ars.usda.gov September 6, 2000 ___________________________________________ Growing wheat before planting a new apple orchard on former orchard land may help growers prevent a crippling condition known as replant disease. Another benefit: It could serve as an alternative to methyl bromide and other soil fumigants typically used to sterilize old orchards before planting new ones. When nothing is done between taking out an old orchard and putting in a new one, the young trees are often stunted and have small, decayed root systems. Plant pathologist Mark Mazzola at ARS' Tree Fruit Research Laboratory in Wenatchee, Wash., discovered that in the Pacific Northwest, replant disease seems to be caused by buildup of four types of soilborne fungi. While soil where apple trees grow supports these fungi, wheat plants seem to modify the soil to favor other microorganisms. Mazzola found a bacterium in some wheat soils, Pseudomonas putida, that can protect young apple roots from the destructive fungi. ARS has patented use of a strain of this bacterium to prevent replant disease. The next step is to determine how long wheat would have to be grown as a rotation crop to change the soil microbial community enough to stave off replant disease. Mazzola will also look at whether growing the wheat as a cover crop in existing orchards can reduce fungal populations sufficiently to allow new trees to grow well. ARS is the chief scientific agency of the U.S. Department of Agriculture. The apple replant disease research is part of a nationwide program of horticultural research within ARS. For more information on ARS research programs that impact on horticulture, visit the web page for ARS national programs in Crop Production, Product Value and Safety: http://www.nps.ars.usda.gov/programs/cppvs.htm An article about the replant research appears in the September issue of Agricultural Research magazine and online at: http://www.ars.usda.gov/is/AR/archive/sept00/rotate0900.htm ___________________________________________ Scientific contact: Mark Mazzola, ARS Tree Fruit Research Laboratory, Wenatchee, Wash., phone (509) 664-2280, fax (509) 664-2287, mazzola@tfrl.ars.usda.gov. ___________________________________________ This item is one of the news releases and story leads that ARS Information distributes on weekdays to fax and e-mail subscribers. You can also get the latest ARS news on the World Wide Web at www.ars.usda.gov/is/pr/thelatest.htm. * Feedback and questions to ARS News Service via e-mail: isnv@ars-grin.gov. * ARS Information Staff, 5601 Sunnyside Ave., Room 1-2251, Beltsville MD 20705-5128, (301) 504- 1617, fax (301) 504-1648.