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Canopy Structure and Irrigation Influence White Mold Disease and Microclimate of Dry Edible Beans. B. L. Blad, Associate Professor, Agricultural Meterology Section, Department of Agricultural Engineering, University of Nebraska, Lincoln, NE 68583; J. R. Steadman(2), and A. Weiss(3). (2)Associate Professor, Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583; (3)Assistant Professor, Panhandle Station, Scottsbluff, NE 69361. Phytopathology 68:1431-1437. Accepted for publication 27 April 1978. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1431.

The severity of white mold of dry edible beans caused by Sclerotinia sclerotiorum was greatly influenced by the structure of the plant canopy and by the amount and frequency of irrigation. The more frequently irrigated cultivar Great Northern Tara developed the most dense canopy and the less frequently irrigated cultivar Aurora had the most open canopy. The most dense canopy was the coolest, wettest, and had the highest severity of disease whereas the most open canopy was the warmest, driest, and had a very low incidence of white mold. This suggests that the severity of white mold was associated with differences in the microclimate of the plant canopy, so that at least partial control of white mold can be obtained through planting cultivars with open canopy structures, avoiding excessive irrigation, and other practices which modify the microclimate to create less favorable conditions for white mold development. Severely diseased plants were several degrees warmer than those with little or no disease. Crop temperature, as obtained through aerial surveillance techniques, may therefore be useful for detecting and delineating areas of white mold in fields of dry edible beans.

Additional keywords: Whetzelinia sclerotiorum, Phaseolus vulgaris, disease control, remote sensing, plant stress, crop temperature, microclimate modification.