Effect of Pesticides and Nitrogen Fertility on Rhizoctonia Root Rot of Sugarbeet

Abstract

The presence and incidence of root and crown rot of sugarbeet (Beta vulgaris L.), caused by the soil-borne fungus Rhizoctonia so­ lani Kuhn, has been reported in the United States by numerous authors, first by Pammel (5)3 in 1891 and most recently by Hecker and Ruppel (3) in 1977. An increasing incidence of the disease was noted by Hecker and Ruppel (3) without attributing a cause, but shorter crop rotations were implicated. Crop rotation currently is the only means of control. Chemical treatments of soil, seed, or plants are not sufficiently effective or are not commercially feasible, and resistant commercial varieties are not yet available. Potential effects of contemporary pesticide treatments on rhi­ zoctonia root rot in field-grown sugarbeet have not been reported. However, Altman and Campbell (1) and Tisserat et al. (7) have re­ ported increased rhizoctonia damping off of sugarbeet seedlings in greenhouse and growth chamber experiments where the soils were amended with cyc10ate and aldicarb. The effect of nitrogen fertility on sugarbeet root rot has been tested only to a limited extent. Hills and Axtell (4) in 1950 reported a lower incidence of rhizoctonia root rot on nitrogen fertilized plots than on non-fertilized plots. Schuster and Harris (6) in 1960 reported similar results on plots of continuous beets and in a 2-year rotation, but not in 3, 4, or 6 year rotations. The purpose of this paper is to report the effects of commonly used pesticides and of nitrogen fertility treatments on rhizoctonia root rot of sugarbeet.