Submitted to: Journal of American Pomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2005
Publication Date: 4/1/2005
Citation: Biggs, A., Miller, S.S. 2005. Relative susceptibility of ne-183 apple cultivars to fruit rot pathogens in west virginia. Journal of American Pomological Society. April 2005. Vol 59; Pages 72-77. Interpretive Summary: Fruit rots caused by various pathogens are a major concern in the production of apples in the mid-Atlantic growing region of the United States. Warm wet conditions during the summer lead to significant rot development and necessitate the use of fungicidal sprays. Identifying rot susceptibility of new apple cultivars is important in selecting new varieties to be planted in this region. Methods developed by the authors in previous studies were utilized in controlled field and laboratory inoculation studies for 21 relatively new and two established apple varieties. Results from these studies permitted the selected apple varieties to be classified from most susceptible to least susceptible for three important rot diseases, black rot, white rot, and bitter rot. This information will aid apple growers and extension fruit specialists in selecting the most disease resistant apple cultivars (varieties) for planting.
Technical Abstract: Twenty-three apple (Malus x domestica Borkh.) cultivars were tested over a five-year period with controlled inoculations in the field and laboratory for their relative susceptibility to the pathogens that cause preharvest fruit rot diseases in the mid-Atlantic region of the United States. Pathogens tested were isolates of Colletotrichum acutatum, Botryosphaeria dothidea, and B. obtusa, the causal agents for bitter rot, white rot, and black rot respectively. Wounded (for Botryosphaeria spp.) or nonwounded (for C. acutatum) fruit were inoculated in the field and laboratory at two-to-three weeks preharvest with mycelium (for Botryosphaeria spp.) or conidia (for C. acutatum) from axenic cultures. Fruit were rated for relative susceptibility to the different fungi by determining disease severity of attached fruit in the field based on lesion growth (mm/degree-day) and detached fruit in laboratory inoculations of wounded fruit (mean lesion diameter after five days). Based on the laboratory and field data from five growing seasons, cultivars were classified into three relative susceptibility groups: most susceptible: 'Pristine', 'Fortune', 'Sunrise', 'Orin', and 'Arlet'; moderately susceptible: 'Sansa', 'Ginger Gold', 'Golden Supreme', 'Honeycrisp', 'PioneerMac', 'Suncrisp', 'Cameo', 'Senshu', 'Shizuka', 'Yataka', and 'NY75414'; and least susceptible: 'Enterprise', 'Golden Delicious', 'Creston', 'GoldRush', 'Gala Supreme', 'Braeburn', and 'Fuji'. Results of the present study indicate that new apple cultivars from the first NE-183 planting vary in their resistance to the different rot fungi and none, perhaps with the exception of 'Gala Supreme' and 'Fuji' shows uniform resistance to the spectrum of rot pathogens included in these experiments.