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Poster: Biology & Disease Mgmt: Mycology


Characterization of fungi associated with tomato leaf mold in the United States
L. GARBER (1), N. LeBlanc (2), A. Orshinsky (1), C. Smart (3) (1) University of Minnesota, U.S.A.; (2) University of Minnesota, U.S.A.; (3) Cornell University, U.S.A.

Tomato leaf mold is one of the most prevalent diseases affecting high tunnel-grown tomatoes in the USA. Disease symptoms include chlorotic to necrotic lesions, defoliation and decreased yields. Previous studies focused on the fungus, Passalora fulva (syn: Cladosporium fulvum, Fulvia fulva) as the causal pathogen of leaf mold. Our initial preliminary data suggests that sporulation on lesions is associated with a number of Cladosporium spp., primarily C. cladosporioides and C. pseudocladosporioides. Leaf mold-associated fungi were collected from MN and NY by surface sterilization of symptomatic tissue and by direct plating of spores from lesions. Single spore isolates were generated and PCR amplification of internal transcribed spacer regions and alpha-actin were performed. Amplicons were sequenced and aligned with available reference species sequences obtained from GenBank using Seaview. A majority of leaf mold isolates collected fell within the C. cladosporioides complex. Representative isolates from each Cladosporium spp. did not appear to be pathogenic. The frequency with which C. cladosporioides and C. pseudocladosporioides are associated with leaf mold lesions suggests that they may be important in the epidemiology and etiology of the disease. Studies regarding the association between C. cladosporioides, C. pseudocladosporiodes and leaf mold of tomatoes are ongoing and may lead to the development of unique disease management strategies in high-tunnel tomatoes.