Control of Apple Replant Disease with Formaldehyde in Washington. R. P. Covey, Plant Pathologist, Tree Fruit Research Center, Washington State University, Wenatchee 98801. B. L. Koch, Associate Horticulturist and Soil Scientist, and H. J. Larsen, Assistant Plant Pathologist, Tree Fruit Research Center, Washington State University, Wenatchee 98801; and W. A. Haglund, Plant Pathologist, Northwestern Washington Research and Extension Unit, Mount Vernon 98273. Plant Dis. 68:981-983. Accepted for publication 2 May 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-981.

In greenhouse studies, formaldehyde was as effective as chloropicrin or methyl bromide in alleviating growth suppression indicative of an apple replant disease (ARD) that occurs commonly in apple orchard soil in Washington State. The effective range of formaldehyde was 0.06–0.43 mg/kg in most soils tested. Metalaxyl and a fungicide mixture containing fenaminosulf were not effective. Soil application of formaldehyde in spring but not autumn alleviated ARD in a field test.

Keyword(s): specific apple replant disease.