Symptomatic Responses of Peach Trees to Various Isolates of Botryosphaeria dothidea. P. L. Pusey, Plant Pathologist, USDA-ARS, Southeastern Fruit and Tree Nut Research Laboratory, P.O. Box 87, Byron, GA 31008. C. C. Reilly, Plant Pathologist, and W. R. Okie, Horticulturist, USDA-ARS, Southeastern Fruit and Tree Nut Research Laboratory, P.O. Box 87, Byron, GA 31008. Plant Dis. 70:568-572. Accepted for publication 2 December 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-568.

Peach trees (Prunus persica) were inoculated with isolates of Botryosphaeria dothidea from peach trees inside (PI) and outside (PO) the geographic area in which peach fungal gummosis has been reported and with isolates from nonpeach hosts inside (NI) and outside (NO) the gummosis area. Thirty isolates applied as conidial suspensions to wounds induced gum exudation within 3 mo; however, observations extending beyond 1 yr revealed that all 13 PI isolates except one continued to induce gumming at a high level, whereas all 11 NI isolates except three from Prunus spp., 5 NO isolates, and 1 PO isolate ceased to induce gumming during the longer period. When the percentage of trees dead or with lenticel-associated symptoms (blisters or lesions) was analyzed, only the PI group differed from the uninoculated check after 1 yr. Similarly, in nonwound inoculations with one PI isolate, one NI isolate, B. obtusa, and B. rhodina, only the PI isolate caused gumming and other symptoms associated with lenticels. B. dothidea isolates from peach trees with typical gummosis symptoms may represent a new biotype of the fungus.