A Bioluminescent<i> Xanthomonas campestris </i>pv.<i> campestris </i>Used to Monitor Black Rot Infections in Cabbage Seedlings Treated with Fosetyl-Al. Glenn T. Mochizuki, Department of Plant Pathology, University of Hawaii, Honolulu, Hawaii 96822. Anne M. Alvarez, Department of Plant Pathology, University of Hawaii, Honolulu, Hawaii 96822. Plant Dis. 80:758-762. Accepted for publication 9 April 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0758.

Autophotography of a bioluminescent transconjugant of Xanthomonas campestris pv. campestris provided a reliable means to quantify the extent of bacterial invasion into cabbage (Brassica campestris). A single prophylactic treatment of fosetyl-Al at 4,800 mg kg-1 a.i. as a spray and drench reduced the invasiveness of Xanthomonas campestris pv. campestris on inoculated cabbage seedlings. Multiple treatments did not reduce invasiveness further. The effect of fosetyl-Al was immediate (within 1 h) and persisted for at least 21 days. The efficacy of fosetyl-Al treatments was more pronounced at 20°C and decreased as temperature increased; however, the data indicated a separate effect of temperature on disease development and no direct interaction between temperature and fosetyl-Al treatment.