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Disease Note. Bipolaris sorokiniana Found Causing Lesions on Snapbean in Wisconsin. M. G. Heimann, Department of Plant Pathology, University of Wisconsin, Madison 53706. W. R. Stevenson, and R. F. Rand. Department of Plant Pathology, University of Wisconsin, Madison 53706. Plant Dis. 73:701. Accepted for publication 23 May 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0701C. In late summer of 1988, many leaf tissue samples from snapbean
(Phaseolus vulgaris L.) in a field near Gillett, Wisconsin, showed small
(I mm diameter), brown to black, round to irregular lesions. Bipolaris
sorokiniana (Sacc. in Sorok.) Shoem. was isolated from these lesions
on acidified PDA. Identification was made from these cultures grown
at room temperature and ordinary room illumination. The bean
cultivar Applause was sprayed with a spore suspension of undetermined
density. Plants were kept in a chamber under a mist of 30 sec per
minute for 48 hr and then moved to a 2I-C greenhouse bench. Koch's
postulates were completed. Symptoms resulting from artificial
inoculation were identical to those observed on leaves from the field
samples. Lesions similar to those observed on leaves were found on
pods. This disease may pose a problem for processing beans, since
blanching of the fruit did not mask pod lesions. This disease occurred
in 1964 in New Brunswick and in 1968 in Nova Scotia, Canada (1).
This is the first known appearance of the disease in Wisconsin. |