Control of garlic white rot by soil solarization

Abstract

Two field experiments in 1988–1989 and one in 1989–1990 resulted in the reduction to undetectable levels of Sclerotium cepivorum in the upper 20 cm layer of soil, even in heavily infested soils, after solarization for 8–11 weeks. White rote progress curves in subsequent crops of garlic indicated disease onset ∼4 months after planting. Rates of disease progress and final incidence of dead plants were greatly reduced in solarized plots, with yield increments of 40.6–155.5% over the unsolarized control plots. However, a garlic crop in the second year after solarization had disease levels and yield reductions that were unacceptable to the growers; this is, apparently, attributable to the high incidence of white rot of garlic that can be induced by low inoculum densities in the soil. Disease progress curves in the unsolarized plots suggested that secondary infections occur. The effect of soil solarization on the quality of garlic was beneficial because of the increased growth response observed. Soil solarization, during the summer before the susceptible crop is planted, provides a reliable and practical method of control of white rot of garlic.