Application of Metham Sodium by Sprinkler Irrigation to Control Lettuce Drop Caused by Sclerotinia minor. P. B. Adams, Plant Pathologist, Soilborne Diseases Laboratory, Plant Protection Institute, U.S. Department of Agriculture, Beltsville, MD 20705. S. A. Johnston, Plant Pathologist, Department of Plant Pathology, Cook College, New Jersey Agricultural Experiment Station, Rutgers Research and Development Center, Bridgeton 08302; J. Krikun, Visiting Scientist, Soilborne Diseases Laboratory, Plant Protection Institute, U.S. Department of Agriculture; and H. E. Carpenter, Agricultural Engineer, Department of Agricultural Engineering, Cook College. Plant Dis. 67:24-26. Accepted for publication 14 April 1982. 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, 1983. DOI: 10.1094/PD-67-24.

In laboratory experiments, metham sodium killed nearly 100% of the sclerotia of Sclerotinia minor in soil at rates as low as 25 μg a.i./ml of water. In three field tests, metham sodium applied at 234 L of product per hectare through sprinkler irrigation with 2.4–5.2 cm (1.0–2.1 in.) of water killed 100% of the sclerotia retrieved from plots 1–2 days after application. The incidence of lettuce drop in control plots ranged from 14 to 58%, whereas that in plots treated with metham sodium ranged from 0 to 6%. The amount of metham sodium applied to the fields was 25–33% of the manufacturer's recommended rate and provided 89–91% disease control.

Keyword(s): chemigation, fungigation, soilborne pathogens, soil fumigation.