Author: R. Smith, M. Clymer, D. Dunn, S. Myers
Author Affliation: LCWC
Journal: MT MTU REPORT FINAL Grant c 311018
A field trial to evaluate the ability of Mycoleptodiscus terrestris ( Mt) to control growth of non-native Eurasian
watermilfoil (Myriophyllum spicatum), or EWM, was conducted in the Les Cheneaux Islands (LCI), Michigan during the summer of 2017. Objectives of the trial were to confirm effective biological control of EWM by Mt observed during a 2014 trial conducted in the Les Cheneaux area; and to learn if Mt efficacy against EWM could be reproduced when the fermentation process was conducted in a different laboratory and at a larger scale. Findings indicate that the Mt strain, NRRL TX-05, did retain efficacy in controlling EWM growth in the Les Cheneaux open-water system during the 2017 field trial. Moreover, it was learned that Mt efficacy in controlling EWM growth continues when water temperatures are lower than optimum. The degree to which Mt infected EWM was quantified by measuring biomass reduction as a function of time. Follow-up observations one year post treatment suggest that EWM vigor might be reduced during the season following Mt treatment. Results from LCI field trials evaluating the mycoherbicidal activity of Mt for EWM management are encouraging. Based upon our studies of 1/6th and 1/8th acre plots as well as previous data, Mt is a strong candidate as a commercial competitor to chemical herbicides for EWM management in lakes, harbors and waterways.