Masters Theses

Date of Award

3-1967

Degree Type

Thesis

Degree Name

Master of Science

Major

Landscape Architecture

Major Professor

B. S. Pickett

Committee Members

Homer D. Swingle, Joe S. Alexander

Abstract

There are many types of beans classified as Phaseolus vulgaris L., the most important species of beans grown in the United States. They are produced for market as snap beans, green-shelled beans and dry beans. Only snap beans will be dealt with in this thesis. Snap beans have become an important vegetable crop in the United States, particularly in the Southern States, Northwest, North-east and parts of the West. However, too frequently crop yields are considerably reduced by soil-inhabiting fungi which destroy the roots and often girdle the stem at or immediately below the soil surface. This disease condition is commonly referred to as root rot, but a more correct name is root and stem rot, since both are affected. The condi-tion is usually associated with a complex of pathogenic fungi inhabit-ing the soil. The most important species of the fungi are Rhizoctonia solani, Pythium butleri and Sclerotium rolfsii (18). The infection of the roots and base of the stem causes stunting and wilting of the plant, often followed by death, which results in reduced yields due to poor plant stands. R. solani is the fungus which is considered to be the major cause of root rot of snap beans. The pathogenicity of this organism has been extensively studied in the laboratory and a limited number of experiments has been conducted to control the parasite in beans under field conditions. Control measures have consisted mainly of the application of pentachloronitrobenzene, a soil fungicide, at planting time. Results have been erratic. In addition to pentachloronitrobenzene, some other experimental chemicals have been used. Those tried also failed to give satisfactory control. The purpose of the first phase of this study was to determine the effectiveness of chemical treatments applied in several ways as means of controlling the root rot complex of snap beans in the field. The second phase of the study was to determine the effectiveness of chemicals for the control of R. solani in snap beans and was conducted in a greenhouse.

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