Soil Temperature and Moisture Effects on Sclerotium Germination and Infection of Onion Seedlings bySclerotium cepivorum

Publisher Website
Google Scholar
Abstract
Germination of sclerotia of S. cepivorum in soil dampened with and without garlic extract was optimal at 18.degree. C and -300 millibars (mb) matric potential (field capacity). Seventy-eight percent of slerotia germinated with extract and 16% germinated without extract. Germination was confined to temperatures of 9-24 C at -300 mb and between -12.5 mb and -3 bars at 18.degree. C. Interactions between temperature and soil moisture were more apparent at less optimum temperature and soil moisture combinations. Germination varied more with matric potential than with moisture content of 2 different soils. Only 0.4% of germinating sclerotia formed secondary sclerotia in soil. Decay of sclerotia was similar in soil with and without garlic extract and was directly proportional to increasing temperature and increasing soil moisture. Infection of host plants by sclerotia was confined to temperatures of 6-24.degree. C and -45 mb and -3 bars matric potential. Disease developed more rapidly with increasing temperature within the 6-24.degree. C range, but developed at the same rate for all permissive matric potentials at a given temperature.