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Copyright of Journal of Phytopathology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The spread of the epiphytic population of Xanthomonas campestris pv. vesicatoria and the disease it causes, bacterial leaf spot, were studied in field plots of pepper near Gainesville, Florida. In the summer of 1989, the epiphytic population of X. campestris pv. vesicatoria was dispersed to the west-northwest from point sources of diseased plants. Winds from the southeast during rainstorms were essential for the spread of bacteria in the field. In the autumn of 1989, a focus of bacterial leaf spot developed naturally near the centre of the experimental plot. The epiphytic population of X. campestris pv. vesicatoria increased sharply after a 2-day rain accompanied with strong wind. The wind was believed to be responsible for the transport of bacteria to distances 32 m from the focus. Initially in both seasons, the epiphytic populations occurred as distinct gradients from the focal sources of diseased plants. These gradients flattened over time and the disease incidence increased to near 100%. The increase in the epiphytic populations of the pathogen to > 3.0 log10 (cfu cm-2) on healthy plants away from the foci preceded disease appearance by several weeks. Applications of cupric hydroxide plus mancozeb significantly reduced the epiphytic population of X. campestris pv. vesicatoria on pepper leaves and slowed the spread of disease in the plots. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Phytopathology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The influence of various calcium salts was evaluated on non-inoculated muskmelon plants and on plants inoculated with the Fusarium-wik pathogen, and maintained in silica sand or vermiculite. Disease severity of inoculated seedlings maintained in vermiculite was markedly higher than that of seedlings grown in silica sand, and onset of wilt was recorded earlier in the former. These trends were more conspicuous in seedlings treated with Ca2+, especially when this cation was accompanied by nitrate. In vermiculite — compared with silica sand, Mg and K contents in the shoot were higher while Ca values were lower. Irrespective of the form of calcium salt or the plant's growth medium, the Ca concentration was higher in Fusarium-inoculaxed shoots while K content was depleted, compared with non-inoculated plants. [ABSTRACT FROM AUTHOR]