In-Bed Fumigation for Control of Rhizomania of Sugar Beet. F. N. Martin, Assistant Professor, Plant Pathology Department, University of Florida, Gainesville 32611. E. D. Whitney, Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service, Salinas, CA 93905. Plant Dis. 74:31-35. Accepted for publication 10 July 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1990. DOI: 10.1094/PD-74-0031.

Preplant application of fumigants by single chisel in plant bed centers significantly increased beet and sugar yields of sugar beets 5–6 months old. Products containing dichloropropene were the most effective in controlling rhizomania. In separate studies, application of Telone II at 29.3, 43.9, and 58.6 L/ha raised sugar yields 83–182, 252, and 78–258%, respectively, compared to the control treatments. Vorlex, Vorlex 201, and Pichlor 60 also reduced disease incidence and significantly increased yield when applied at 132.7, 146.1, and 32.7 L/ha, respectively. Sealing the soil with water, although not essential for effective control, significantly increased yield over unsealed treatments with Telone II at 29.3 L/ha and all rates of Vorlex. Although metham-sodium and the low rate of chloropicrin (21.3 L/ha) did not control rhizomania, sugar yields were 42 and 44% greater, respectively, than in control treatments, possibly because other root pathogens were controlled. Protecting plants from infection for the first 9–11 wk after planting appeared to be critical for preventing beet and sugar yield reductions caused by rhizomania.