Epidemiological aspects of bacterial canker of tomato
Chang, Ruey-Jang
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Permalink
https://hdl.handle.net/2142/20825
Description
Title
Epidemiological aspects of bacterial canker of tomato
Author(s)
Chang, Ruey-Jang
Issue Date
1991
Doctoral Committee Chair(s)
Ries, Stephen M.
Department of Study
Crop Sciences
Discipline
Crop Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Agronomy
Biology, Ecology
Agriculture, Plant Pathology
Language
eng
Abstract
Rifampin-resistant strains of Clavibacter michiganensis subsp. michiganensis (CMM$\sp{\rm rif+})$ were used to study the epidemiology of bacterial canker of tomato (Lycopersicum esculentum Mill.). Clipping tomato seedlings in transplant beds with a rotary mower transmitted CMM$\sp{\rm rif+}.$ The incidence of systemically infected plants in production fields increased about 10% for each 0.1% increase in incidence of infected seedlings in the transplant beds. When healthy and diseased seedlings were harvested and mixed in bundles at various rates, CMM$\sp{\rm rif+}$ was spread from diseased to healthy seedlings. Incidence of systemically infected plants in production fields increased about 3-5% for each 1% increase in the percentage of diseased seedlings.
The bacterium was transmitted at a low rate from seed to transplants. Survival of CMM$\sp{\rm rif+}$ associated with infested tomato debris was greater from debris on the soil surface than from buried debris. Populations of CMM$\sp{\rm rif+}$ fluctuated from 0 to about 10$\sp9$ cfu/g fresh weight on solanaceous plants and from 0 to about 10$\sp3$ cfu/g fresh weight on non-solanaceous weeds. Susceptible and moderately resistant tomato cultivars supported epiphytic populations of about 10$\sp7$-10$\sp9$ cfu/g fresh weight. Symptoms of secondary infection, marginal leaf scorch of leaflets or bird's eye spot of fruit, were not observed until populations exceeded 10$\sp6$ and 10$\sp7$ cfu/g fresh weight for the moderately resistant and susceptible cultivar, respectively.
The incubation period and severity of symptoms of tomato were influenced by temperature, age of plants, concentration of inocula, and host cultivar. The mean incubation period varied from 12-34 days depending on conditions. Cool temperatures, older plants, lower concentrations of inocula, and moderately resistant cultivars not only increased the incubation period but also decreased the severity of symptoms.
Total fruit weight decreased about 0.5-1.2 Kg per plot, maximum yield decreased about 0.5-0.7%, and average fruit weight decreased about 0.1-0.3 g for each 1% increase in incidence of plants systemically infected with bacterial canker. The percentage of green fruit decreased about 0.2-0.9% and the percentage of ripe or rotten fruit increased about 0.2-0.9% for each 1% increase in incidence.
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