Differentiation of a Fusicoccum sp causing panicle and shoot blight on California pistachio trees from Botryosphaeria dothidea

A panicle and shoot blight disease of pistachio trees in California is caus ed by a fungus previously identified as the anamorph of Botryosphaeria doth idea. We have compared random amplified polymorphic DNA (RAPD) markers, nuc lear rDNA internal transcribed spacer (ITS) region sequences, and conidium morphology of 15 isolates of the pistachio Fusicoccum to those of well-char acterized isolates of B. dothidea, B. ribis, and F luteum. Cluster analysis of RAPD markers separated the pistachio Fusicoccum isolates from B. dothid ea, as did parsimony analysis of the ITS region sequences, Conidium size an d shape were similar to those of B. ribis (Fusicoccum sp.) and F luteum, bu t distinguishable from those of F. aesculi (the anamorph of B. dothidea). W e conclude that the fungus causing panicle and shoot blight of pistachio is distinguishable from B. dothidea and is part of a complex containing B. ri bis, E luteum, and other fungi with Fusicoccum anamorphs.