New bacterial watermelon fruit blotch in Florida
A new bacterial watermelon fruit blotch disease has been reported in Florida, US. The disease was first observed in spring 1989 on watermelons showing large, firm, dark green and water-soaked lesions with irregular margins. In some fields yield losses up to 50% due to the pathogen were reported.
The symptoms were similar to those of Pseudomonas pseudoalcaligenes subsp. citrulli which were first observed in 1965 in Florida.
Laboratory studies resulted in the isolation of a gram-negative, aerobic, rod-shaped , oxidase-positive and arginine dihydrolase-negative bacterium which was morphologically , physiologically and biochemically related to P. a. subsp. citrulli. However, in contrast to the previously described bacterium the new watermelon strains produced hypersensitive responses in tobacco and tomato.
During 1989 the disease was further reported in South-eastern, mid-Atlantic and mid-Western states.
Sources
Somodi, G.C.; Jones, J.B.; Hopkins, D.L.; Stall; R.E.; Kuchorek, T.A.; Hodge, N.C.; Watterson, J.C. (1991) Occurrence of bacterial watermelon fruit blotch in Florida.
Plant Disease 75, 1053-1056