Growth and Competition between Lentinus edodes and Trichoderma harzianum on Sawdust Substrates

Abstract

The effect of environmental and cultural conditions on the growth and competition between shiitake mushroom mycelium and the competitor Trichoderma harzianum was investigated. T. harzianum had higher growth rates and temperature optimum and tolerated more variable pH. T. harzianum grew at lower water potentials than did L. edodes. No difference was detected in growth or dual challenge culture under moderate levels of CO2, pre-exposure to T. harzianum, low levels of sucrose and KCl supplementation, and substrate moisture contents between 39% and 70%. Conditions that favored the growth of L. edodes over T. harzianum were moisture contents above 35%, 2 or 4 h of autoclaving the substrate, the use of oak sawdust in place of a hickory-ash mixture, the use of weathered sawdust, supplementation with 4% gypsum, low levels of bran supplementation, partial replacement of organic nitrogen sources with urea, and low levels of straw supplementation. Shiitake strain 465 exceeded strain 305 in its ability to compete with Trichoderma when grown on a 9% bran supplemented medium. A simple technique was developed for in situ observations of growth and fungal interactions.