VIEW ARTICLE

Soil Moisture Effects on Control of Pythium ultimum or Rhizoctonia solani with Methyl Bromide. Donald E. Munnecke, Professor of Plant Pathology, Department of Plant Pathology, University of California, Riverside 92502; B. J. Moore(2), and F. Abu-El-Haj(3). (2)(3)Laboratory Technicians, respectively, Department of Plant Pathology, University of California, Riverside 92502. Phytopathology 61:194-197. Accepted for publication 21 September 1970. DOI: 10.1094/Phyto-61-194.

Peat moss:fine sand mixture (U.C. mix) infested with Pythium ultimum or Rhizoctonia solani was fumigated continuously for 1, 2, 5, or 8 days with approx 600, 1,200, or 2,300 parts per million of methyl bromide gas in air to measure the effects of varying soil moisture on the efficacy of the fumigant in controlling damping-off of peas. The effect of soil moisture on control of damping-off was pronounced in soil infested with P. ultimum, but not so pronounced in soil infested with R. solani. Most effective control of P. ultimum was obtained in moderately moist soil (12% water), next in very wet soil (37% water), and least in very dry soil (2% water). With R. solani, best control of damping-off was obtained in moderately moist soil (10% water). In contrast to results with P. ultimum, control of damping-off due to R. solani in very wet soil (37% water) and in very dry soil (2% water) was similar and only slightly poorer than that obtained in moderately moist soil.