VIEW ARTICLE

Ecology and Epidemiology

A New Pellet Soil-Sampler and Its Use for the Study of Population Dynamics of Rhizoctonia solani in Soil. Y. Henis, Professor, Department of Plant Pathology and Microbiology, Hebrew University of Jerusalem, Israel; A. Ghaffar(2), R. Baker(3) and S. L. Gillespie(4). (2)Associate Professor and Fulbright-Hays Scholar, Department of Botany, University of Karachi, Pakistan; (3)Professor, Botany and Plant Pathology Department, Colorado State University, Fort Collins, CO 80523; (4)Engineer, 4705 Venturi Lane, Fort Collins, CO 80521. Phytopathology 68:371-376. Accepted for publication 26 July 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-371.

A new soil sampler is described and its use for quantitative estimation of propagules of Rhizoctonia solani in soil is reported. The sampler produces soil pellets of predetermined weight and deposits them on any smooth surface, including an agar medium. It has been used either in the form of a multiple-pellet or as a single-pellet soil sampler. When used as a multiple sampler, 15 soil pellets, each weighing 50 to 500 mg (adjustable capacity), are produced and placed at a fixed position on an agar medium. With 10 successive samples, standard error of the mean weights is less than 2%. Increasing dilutions of Rhizoctonia inoculum in soil related linearly to the number of Rhizoctonia-containing soil pellets when corrected for multiple colonization. Typical mycelium of R. solani growing from a pellet is easily recognized, and both presence and vigor of the propagules can be determined. The sampler is especially useful in counting soil microorganisms at levels ranging between 1-10 propagules/g but lower levels can be measured by increasing sample size whereas for higher levels appropriate soil dilutions should be made. The use of this sampler in the study of soil microorganisms other than R. solani is possible.