Relative susceptibility of ornamental peach cultivars to fungal gummosis (Botryosphaeria dothidea).

Peach fungal gummosis, incited by Botryosphaeria dolhidea (Moug.:Fr.) Ces. & De Not., is an unsightly disease of peach trees [Prunus persica (L.) Batsch] that depresses growth and can cause significant dieback and even tree death on susceptible peach cultivars. Little is known about the relative susceptibility of ornamental peach cultivars utilized in the United States landscape industry. Peach prunings inoculated with B. dothidea and placed on trellis wires served as an inoculum source which was delivered to the test subjects planted below via intermittent misting during March through June of the first year. Disease severity was evaluated at the end of the second growing season after visible symptoms developed. The 13 ornamental genotypes tested separated into four distinct classes with 'White Glory', 'Jerseypink' and PI091459 ('Red Weeping') in the most susceptible, and 'Helen Borchers' and 'McDonald' in the most resistant classes. Trunk cross-sectional area at the end of the second growing season and relative growth rate during the second growing season were negatively correlated with gummosis severity.