Factors Affecting Germination of Spores of Wood-Rotting Fungi on Wood

Basidiospores of wood-rotting fungi (L. trabea, L saepiaria, and F. roseus) were collected from fruit bodies produced in storage dishes containing 50 ml. of 2 percent malt agar and subsequently allowed to germinate on wood sections cut 60 microns thick and 5 mm. square. In preliminary studies using isolates of L. trabea and Douglas-fir wood, spore concentration had no effect on percentage germination, and there were no significant differences between germination on springwood and summerwood of Douglas-fir. Heating wood when wet reduced spore germination of L. trabea. Spores of L. trabea placed on heartwood of western redcedar did not germinate and appeared to disintegrate. Higher percentages of F. roseus basidiospores germinated on nonextracted than on extracted Douglas-fir sapwood. Spores soaked for 5 days at 22?C. germinated in less time than spores soaked for 1 hour or spores not soaked; this advantage appeared to be only temporary since, after 30 hours, more of the non-soaked spores germinated than soaked spores. Results from relative humidity tests with basidiospores of L. trabea indicate that germination percentages are high at 99 percent relative humidity or above; small differences in relative humidity above 99 percent affect both the total amount of germination as well as the time required to reach maximum percentage germination. Highest percentage germination of the basidiospores of L. saepiaria occurred at temperatures from 27? to 35?C. Maximum percentage germination of the basidiospores of. L. trabea occurred at 27? and 40?C. The reasons for the bimodal curve in the case of L. trabea were not determined. The basidiospores of L. trabea were less tolerant of sodium pentachlorophenate than was mycelium in agar. A concentration of 0.001 percent sodium pentachlorophenate significantly decreased germination of basidiospores of L. trabea, but a 0.01 percent concentration was necessary to prevent germination for at least 24 hours and to prevent weight loss when blocks were inoculated for 3 months. As equivalent results were obtained using either weight loss or spore germination, it may be possible to correlate the germination on wood with the weight loss of wood blocks, thus reducing the time required for preservative evaluation from 3 months to 1 day.

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