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Poster: Diseases of Plants: New & Emerging Diseases


Susceptibility of eight untested species of Cucurbitaceae to gummy stem blight under field conditions
G. RENNBERGER (1), A. Keinath (1) (1) Coastal Research and Education Center, Clemson University, U.S.A.

To date, 23 species of 12 genera in the Cucurbitaceae are known to be affected by the cucurbit disease gummy stem blight (GSB), caused by the fungus Stagonosporopsis spp. (Didymella bryoniae). Eight different species representing seven genera of Cucurbitaceae were selected for taxonomic and geographic diversity. Muskmelon (Cucumis melo ‘Athena’), which is highly susceptible, was included as a control. A field trial was set up as a randomized complete block design with four replications and seven inoculated plants per replication to assess the susceptibility of these species. The severity of the foliar blight phase and the incidence of the crown canker phase of GSB were rated. Ecballium elaterium showed the highest severity to foliar blight, followed by Apodanthera sagittifolia and Kedrostis leloja. These species were more susceptible than the control. A group of five species, Acanthosicyos horridus, Cucurbita digitata, Cucurbita ecuadorensis, Cucumis zambianus and Melothria scabra, were as susceptible to foliar blight as the control. The highest incidence of cankers was observed on crowns of K. leloja and ‘Athena’ muskmelon, followed by C. zambianus, A. sagittifolia and E. elaterium in decreasing order. The pathogen was recovered from crowns of all species. This is the first report of susceptibility of these eight cucurbit species to GSB.