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United States Department of Agriculture

Agricultural Research Service


item Chae, Dong Hyun
item Jin, Rong De
item Hwangbo, Hoon
item Kim, Yong Woong
item Kim, Yong Cheol
item Park, Ro Dong
item Krishnan, Hari
item Kim, Kil Yong

Submitted to: Biocontrol
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2005
Publication Date: 6/27/2006
Citation: Chae, D., Jin, R., Hwangbo, H., Kim, Y., Kim, Y., Park, R., Krishnan, H.B., Kim, K. 2006. Control of late blight (phytophthora capsici) in pepper plant with a compost containing multitude of chitinase-producing bacteria. Biocontrol. 51:339-351.

Interpretive Summary: The late blight disease causes serious damage to important crops world-wide resulting in significant loss of revenue. To date, synthetic chemical fungicides have been the most efficacious method used to control this disease. Use of fungicides has been associated with deterioration of soil physico-chemical properties, accumulation of toxic compounds, and an increase in pathogen resistance. Longevity and slow degradation rate of chemicals creates potential environmental and human health concerns. These concerns have forced researchers to find innocuous yet efficacious methods of disease control. Several soil microbes, which produce an array of biologically active compounds, can serve as potential biological control agents. In this study, we have demonstrated chitinase producing soil microbes can significantly protect pepper plants from late blight caused by Phytophthora capsici. Information obtained from this study demonstrates that chitinase-producing soil bacteria could be utilized as potential biocontrol agents of important diseases. This practice should reduce the use of undesirable synthetic chemicals and promote maximum yield of important vegetable crops.

Technical Abstract: Compost sustaining a multitude of chitinase-producing bacteria was evaluated in a greenhouse study as a soil amendment for the control of late blight (Phytophthora capsici L.) in pepper (Capsicum annuum L.). Microbial population and exogenous enzyme activity were measured in the rhizosphere and correlated to the growth and health of pepper plant. Rice straw was composted with and without a chitin source, after having been inoculated with an aliquot of coastal area soil containing a known titer of chitinase-producing bacteria. P. capsici inoculated plants cultivated in chitin compost-amended soil exhibited significantly higher root and shoot weights and lower root mortality than plants grown in pathogen-inoculated control compost. Chitinase and beta-1,3-glucanase activities in rhizosphere of plants grown in chitin compost-amended soil were twice that seen in soil amended with control compost. Colony forming units of chitinase-producing bacteria isolated from rhizosphere of plants grown in chitin compost-amended soil were 103 times as prevalent as bacteria in control compost. These results indicate that increasing the population of chitinase-producing bacteria and soil enzyme activities in rhizosphere by compost amendment could alleviate pathogenic effects of P. capsici.

Last Modified: 10/18/2017
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