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Ecology and Epidemiology

Emergence, Growth, and Development of Dry Bean Seedlings in Response to Temperature, Soil Moisture, and Rhizoctonia solani. A. H. C. van Bruggen, Former graduate research assistant, Department of Plant Pathology, Cornell University, Ithaca, NY 14853, Present address: Boyce Thompson Institute at Cornell University, Ithaca, NY 14853; C. H. Whalen(2), and P. A. Arneson(3). (2)(3)Technical assistant, and associate professor, respectively, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. Phytopathology 76:568-572. Accepted for publication 27 November 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-568.

The rates of emergence and initial seedling growth of red kidney beans were determined in response to various conditions of temperature and soil moisture in the presence and absence of Rhizoctonia solani. In incubators, the optimal temperature and soil moisture for seedling emergence were around 27 C and 20% (-0.2 bar). R. solani delayed emergence, reduced the growth rate, and increased the shoot:root ratio, particularly at temperatures above 18 C and at low soil moisture levels. The proportion of plants infected was dependent only on temperature (optimum at 24-30 C). Lesion size was determined primarily by soil moisture (largest at 10% or -9.5 bar).