SUPPRESSION OF MYCORRHIZAL FUNGI IN FESCUE BY THE ACREMONIUM-COENOPHIALUM ENDOPHYTE

Propagule population densities of the nine mycorrhizal species detected in field plots planted to tall fescue free of the Acremonium coenophialum endophyte were more than double those in plots planted to fescue heavily infected with Acremonium. Seedlings of Acremonium-free fescue detected more propagules of most of the eleven mycorrhizal species detected in a field soil than seedlings infected with Acremonium. Sporulation by three mycorrhizal isolates over 17 weeks was higher on fescue seedlings free of Acremonium than on seedlings infected with Acremonium. Since mycorrhizal fungi are believed to be confined to roots and Acremonium endophytes to shoots, the inhibitory effect of Acremonium on mycorrhizal fungi may be due to the translocation to roots of alkaloids produced by the Acremonium-Festuca symbiosis.