Evaluation of Weeds and Plant Refuse as Potential Sources of Inoculum ofPseudomonas syringaein Bacterial Canker of Cherry

Abstract

P. syringae, which causes bacterial canker of sour cherry, was recovered from weeds and plant refuse collected under Montmorency sour cherry trees in 3 locations in Michigan [USA]. Isolates of P. syringae were recovered periodically from May 7, 1977 to May 18, 1978, while P. morsprunorum was recovered from only 3 of 54 weed samples and not from plant refuse. In greenhouse experiments, isolates of P. syringae from weeds and plant refuse were pathogenic to sour cherry leaves and shoots, peach seedlings, and sweet cherry fruit, and under wet conditions colonized and infected uninjured Montmorency sour cherry leaves. The potential of weeds and plant refuse as sources of inoculum for bacterial canker of cherry is discussed.