Susceptibility of various potted begonias to Fusarium foetens

Abstract

Fusarium foetens was recently reported on greenhouse Hiemalis begonia (Begonia × hiemalis Fotsch) in Canada, causing disease symptoms which consist of a dull green leaf colour, wilting, and vascular necrosis. During our greenhouse trials, a concentration of 100 conidia mL−1 added to the growing substrate was sufficient to cause severe disease symptoms. F. foetens symptoms were observed as early as 2 weeks after inoculation, for highly susceptible Hiemalis begonia cultivars (i.e. ‘Berseba’ red, ‘Golden Edith’ yellow and red, ‘Rainbow Spectrum’ white, ‘Berseba’ hot pink). Disease symptoms were observed 3 weeks following inoculation for moderately susceptible Hiemalis begonia cultivars (i.e. white ‘Netja’, ‘Binos’ pink, ‘Batik’ orange, ‘Solenia’ velvet red, ‘Rainbow Spectrum’ pink chablis and ‘Netja’ dark pink), and after 4 weeks for slightly susceptible cultivars (i.e. ‘Rainbow Spectrum’ and ‘Rainbow Spectrum Vivian’). The Hiemalis begonia cultivar ‘Rainbow Spectrum Camilla’ was ranked as moderately resistant. Other begonia types such as Rex begonia hybrid (Begonia rex-hybrid Putz.), Fibrous begonia (Begonia semperflorens Hook.), and Tuberous begonia (Begonia tuberhybrida Voss), which exhibited symptoms 12 weeks following F. foetens inoculation, were considered resistant. Additional ornamental species (i.e. petunia ‘Polo Rose Flare’, impatiens ‘Balfieplos’ and poinsettia ‘Prestige’) inoculated with F. foetens did not develop visible disease symptoms, suggesting that F. foetens may be relatively host specific to begonia.