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Disease Note Occurrence of Aphanomyces euteiches f. sp. phaseoli on Beans in New York State. H. R. Dillard, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456. G. S. Abawi, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456. Plant Dis. 72:912. Accepted for publication 22 July 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0912C.
Root and hypocotyl rot of beans (Phaseolus vulgaris L.) incited by
Aphanomyces euteiches Drechs. f. sp. phaseoli was observed for the
first time in commercial fields in the western area of New York State
during 1986. The disease was first recorded on beans in the United
States in 1982 (1). The pathogen was isolated by plating washed root
and hypocotyl segments of symptomatic plants obtained from two
fields on Aphanomyces-selective medium (2) at 25 C. Roots of 8- to
IO-day-old bean seedlings (cv. Bush Blue Lake 47) were dipped in
mycelial fragment or zoospore inocula of this pathogen and
transplanted into steam-pasteurized soil. The fungus caused severe root
rot symptoms and significantly reduced dry weight ofthe bean seedlings
in the greenhouse. No symptoms were observed on pea (Pisum sativum
L. 'Knight') or table beets (Beta vulgaris L. 'Ruby Queen'), confirming
the identity of the pathogen as A. e. f. sp. phaseoli. Seed and soil
treatments using fenaminosulf, but not metalaxyl, were highly effective
in controlling the disease. |