Download Microbial Treatments for Residue Removal and Pathogen Control

Microbial Treatments for Residue Removal and Pathogen Control
Don L. Crawford and Janice L. Strap. Department of Microbiology, Molecular Biology and
Biochemistry, University of Idaho, Moscow, ID.
The goal of maintaining the long-term health, vigor, and seed yields of bluegrass fields in
the absence of open-burning will require new management practices that enhance grass residue
turnover rates while controlling the emergence of fungal pathogens and other pests after
elimination of burning. We are examining an alternative that should help achieve this goal, via
the use of microbial amendments in combination with other residue management practices. A
mixture of two compatible strains of saprophytic, nonpathogenic residue-degrading bacteria will
be used. These bacteria are also antagonists of fungal plant pathogens. When spread on fields
containing bluegrass residues, they should colonize and rapidly decompose the residues while
also controlling the buildup of fungal pathogens. The bacteria, Streptomyces hygroscopicus
strains YCED9 and WYE53, are members of the antifungal lignocellulose-degrading
actinomycete group of bacteria. They were initially isolated and developed into antifungal
biocontrol agents and biological dethatch agents for use in turf. Microbial formulations will be
applied within subplots of the chemical fallow-harrow treatments, mechanical removal (bale)
treatment, and to each of the cattle grazing treatments directly after the cattle have been removed
from the plots.
We hypothesize that the bluegrass residue decomposition rates will be greatly enhanced
as the result of degradation by the added actinomycetes, particularly after surface soil disruption,
resulting from tilling or short term intensive grazing. These activities will mix the remaining
residues into the surface layer of the soil where they will be rapidly degraded by the added
microbes. At the same time, the actinomycetes will control the buildup of fungal pathogens.
The results of the microbial treatments will be assessed by monitoring residue decomposition
rates as well as total microbial, actinomycete, and fungal counts over time in treated versus
control plots. The plots will be also be available to other investigators on the team who will be
monitoring other parameters. Ultimately, we will determine how these treatments, alone or in
combination with the other management alternatives, affect Kentucky bluegrass stand health and
seed yield over the long term (> 3 years).