|Roberts, P. D. - UNIV. OF FLORIDA|
Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2006
Publication Date: June 1, 2006
Citation: Roberts, P., Adkins, S.T., Bruton, B.D. 2006. Fungi and bacteria associated with watermelon vine decline in Florida [abstract]. American Phytopathological Society. S1:88. Technical Abstract: Since 2003, a watermelon vine decline of unknown etiology has caused widespread crop loss in South Florida. As fruit approached maturity, the foliage turns yellow, then scorched and brown, followed by collapse of the entire vine. A uniform tan to light brown discoloration of the xylem was observed. Although there are no external symptoms, fruit frequently exhibited greasy-brown blotches in the rind. Standard isolation techniques yielded numerous fungi and bacteria from crown, root and fruit tissue. The fungi most frequently isolated were: Fusarium oxysporum, F. semitectum, Plectosporium tabacinum, Rhizoctonia solani, Pythium spp. and Didymella bryoniae. P. tabacinum was often isolated from the vascular tissue 10-30 cm above the crown. Race 0, 1, and 2 of Fusarium oxysporum f. sp. niveum are often isolated from symptomatic plants, but vine decline symptoms are distinct from Fusarium wilt. Some bacterial strains caused tissue maceration and/or necrosis or brown blotches similar to field symptoms on fruit. The role of fungi, bacteria, viruses and other factors continue to be investigated.