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Effect of Bactericides on Population Sizes and Spread of Clavibacter michiganensis subsp. michiganensis on Tomatoes in the Greenhouse and on Disease Development and Crop Yield in the Field

January 2000 , Volume 90 , Number  1
Pages  38 - 44

M. K. Hausbeck , J. Bell , C. Medina-Mora , R. Podolsky , and D. W. Fulbright

First, second, third, and fifth authors: Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824-1312; and fourth author: Department of Biology, University of Michigan—Flint, Flint 48502

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Accepted for publication 27 September 1999.

Chemical applications, with the exception of mancozeb, reduced population sizes and spread of Clavibacter michiganensis subsp. michiganensis among tomato seedlings in the greenhouse and impacted subsequent plant development and yield in the field. While applications of copper hydroxide, copper hydroxide/mancozeb, copper hydroxide/mancozeb (premixed 12 h before spraying), streptomycin, and streptomycin/copper hydroxide to seedlings in the greenhouse did not differ significantly from the inoculated control, the trend was for these treatments to increase the survival of inoculated transplants in the field in comparison to the inoculated control. In the field, inoculated controls produced yields that were 63% (1995) and 51% (1996) of those produced by uninoculated controls. In both years, with the exception of mancozeb in 1995, all treatments resulted in yields similar to those obtained with the uninoculated control. Plant survival and yield in the field were severely affected when transplants had a pathogen population of ≥ × 108 CFU/g of tissue. All treatments, with the exception of mancozeb, limited C. michiganensis subsp. michiganensis populations to <5.0 × 105. None of the treatments significantly reduced the incidence of fruit spotting compared with that of the inoculated control.

Additional keywords: bacterial canker.

© 2000 The American Phytopathological Society