Date of Award:

5-1970

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Plant Pathology

Committee Chair(s)

O. S. Cannon

Committee

O. S. Cannon

Committee

W. S. Boyle

Committee

J. L. Anderson

Committee

P. B. Carter

Committee

W. G. Dewey

Abstract

The detection and identification of bacterial pathogens in bean tissues can be accomplished with relative ease and certainty by utilizing antiserum prepared against specific bean pathogens. This test requires only fifteen minutes to complete, and a minimum amount of equipment. In addition to speed and ease, it eliminates the difficult process of isolating the bacterial pathogens from the many contaminants that will grow in nutrient culture techniques. The advantage of this technique is primarily based on the utilization of the bacterial population already present in the diseased plant tissues.

The effectiveness of this method has been demonstrated by diagnosing beans infected with Pseudomonas phaseolicola, P. syringae, Xanthomonas phaseoli and X. phaseoli var. fuscans.

In addition to detection and identification, antibiotic control measures for halo blight have been investigated. Seed treatment with streptomycin was the best treatment for controlling halo blight. The second most successful antibiotic was chloromycetin; this was followed by aureomycin, and kanomycin plus 1% trionic. The antibiotics were rated under greenhouse conditions favoring the pathogen and disease development. Phytotoxicity was considered.

The tetracycline group of antibiotics gave the best bacterial inhibition in vitro. Phytotoxicity is a problem that appears in greenhouse tests with aureomycin. Some plants germinated with white leaves causing noticeable stunting. Kanomycin toxicity was the most severe because the affected plants were unable to develop beyond the first two-leaf stage. Chloromycetin and streptomycin caused the least amount of observable toxicity.

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