Temperature,time, and the influence of volatiles on phialospore germination in Verticillium malthousei Ware

Phialospores of Verticillium malthousei Ware were atomized onto acclimatized water agar and incubated for 3, 6, 9, 12, and 24 hr at 12 to 36 °C at 6 °C intervals. Germination occurred at all temperatures exclusive of 36 °C with maximum germination (90–98 %) occurring in 24 hr at 12 °C, 12 hr at 18 °C, 9 hr at 24° and 30 °C. Volatiles from: 1) horse manure compost colonized by Agaricus bisporus; 2) mycelium impregnated casing (soil); or 3) casing supporting mature and immature mushrooms had no statistically significant effect on spore germination of V. malthousei when measured after 12 hr at 24 °C. However, a tendency towards inhibition after 6 and 12 hr at 24° and 12 °C, respectively, suggests the inhibition is temperature and time dependent. This dependency was noted with two substrates, colonized compost and casing which supported sporocarps.The statistical and programming assistance of Dr. J. A. Ayers, Department of Plant Pathology, Dr. R. Craig, Department of Horticulture, and Ms. Isabel M. Hoover, Agricultural Statistic Laboratory, The Pennsylvania State University is gratefully acknowledged.Contribution No. 759 from the Department of Plant Pathology, The Pennsylvania Agriculture Experiment Station. Authorized for publication as Journal Series Paper No. 455.0 on October 8, 1973.