Infection of Adventitious Roots of Agrostis palustris by Idriella bolleyi1

Seven isolates of Idriella bolleyi obtained from adventitious roots of Agrostis palustris displaying symptotns of thinning, low vigor, and death of turf in a random, nondescript pattern were evaluated for their ability to infect adventitious roots of A. palustris under high and low temperature regimes and to affect plant growth and symptom expression. All isolates of /. bolleyi infected roots under high and low temperature regimes and all but one isolate decreased shoot and root dry weight. Isolate IB-2 decreased dry weight under low temperatures, but not under high temperatures. Stolon growth of root-inoculated plants increased or remained unchanged among plants subjected to high temperature; stolon growth decreased on plants subjected to low temperature. Most isolates of/. ^o/Ze^ʹi decreased the chlorophyll content of leaves of plants subjected to high temperature; chlorophyll content of leaves of inoculated plants subjected to low temperature remained unchanged. Hyphal growth was observed on inoculated adventitious roots and was accompanied by dark clusters of fungal cells and chlamydospores on the epidermis and cessation structures within the cortex. Vascular tissues were not penetrated by /. bolleyi. It was concluded that I. bolleyi can infect adventitious roots of A. palustris as a minor root pathogen and alter root and shoot growth