APS Homepage

POSTERS: Host resistance screening

Susceptibility of Geranium Cultivars to Botrytis cinerea in the Greenhouse
Sunil Shrestha - Michigan State University.

Botrytis cinerea incites leaf, stem, and flower blight and occurs on greenhouse-grown crops including geranium. We evaluated the following geranium cultivars for B. cinerea susceptibility: ‘Maverick’, ‘Multibloom’, ‘Ringo’, ‘Nano’, ‘Bullseye’, ‘Pinto’, ‘Quantum’, ‘Horizon’, ‘Pinto Premium’, and ‘Ivy’. Seed was planted, and plants inoculated 71 days later by spraying a B. cinerea (1x106 conidia/ ml) solution obtained from a geranium isolate; plants were incubated in plastic bags to achieve high relative humidity. Ten single plants per cultivar were evaluated in research greenhouses. The number of blighted leaves and blighted leaves with sporulating B. cinerea, the number of foliar lesions, and overall disease severity ratings (0=no disease; 10=severe disease) were assessed three times beginning 7 days after inoculation. ‘Ringo’, ‘Multibloom’ and ‘Maverick’ were more susceptible based on blighted leaves (>24), blighted leaves with sporulating B. cinerea (>18), number of foliar lesions (>26) and disease severity (>6). ‘Ivy’ had the lowest number of blighted leaves (13), blighted leaves with sporulating B. cinerea (< 9), foliar lesions (<14) and the lowest disease severity (<5). Overall, ‘Ringo’, ‘Multibloom’ and ‘Maverick’ were highly susceptible, ‘Nano’, ‘Bullseye’, ‘Pinto’ and ‘Quantum’ were moderately susceptible, and ‘Pinto Premium’, ‘Horizon’ and ‘Ivy’ were less susceptible. When the experiment was repeated, differences among the cultivars were not observed.