Large-Brown-Spored House-Rot Fungi in the United States

SUMMARY

Cultures of Merulius lacrymans have been distinguished from cultures of other wood-rotting fungi and from cultures of the common species Merulius americanus. The two species of Merulius may be separated by differences in growth rate and mycelial mat characteristics when grown on 2 per cent malt agar in 90 mm. Petri dishes. M. lacrymans grows best at a temperature of about 18° C and does not grow at 28° C. M. americanus grows best at 26° C, grows well at a temperature of 30° C, and will even make a slight growth at 34° C. These Merulius species have been encountered a few times in houses.

Coniophora puteana and Poria incrassata are two species causing destructive decay in houses in this country; they also have large brown spores. However, C. puteana is a much faster growing fungus than the Merulius species and P. incrassata may be differentiated from the other species by its mat and type of growth. Temperature requirements for C. puteana, P. incrassata, and M. americanus are quite similar.