Strawberry plants with red to black, sunken, fusoid lesions on runners and leaf petioles were found in several first-year plantings in grower's fields in western New York in 2000. Affected cultivars included Honeoye, Jewel, and Primetime. Sections of petiole were excised from lesion margins and plated on potato dextrose agar (PDA) amended with chloramphenicol, streptomycin sulfate, and tetracycline hydrochloride at 100 μg/ml. The fungus, Colletotrichum acutatum (J.H. Simmonds), was consistently isolated and identified based on conidia morphology and its growth rate in culture relative to reference cultures of C. acutatum, C. gloeosporoides, and C. fragariae (1,2). The average size of conidia produced on PDA was 15.2 × 5 μm. For each of six isolates, three plants each of six-week-old Honeoye and Kent were spray inoculated with a conidial suspension (106 conidia per ml), and petioles, leaves, and crowns were stabbed with a sterile pin following inoculation. After 14 days at 20 to 25°C, petioles and leaves on all inoculated plants developed lesions consistent with those seen in the field. The fungus was readily reisolated from leaf and petiole lesions. Subsequent inoculations on detached fruit under the same conditions yielded circular, sunken, dry lesions that produced a salmon-colored, slimy, spore mass typical of C. acutatum. This is the second report of strawberry anthracnose in the northeastern United States (3) and to our knowledge, the first report in New York.
References: (1) J. A. García Muñoz et al. Mycologia 92:288, 2000. (2) P. S. Gunnel and W. D. Gubler. Mycologia 84:157, 1992. (3) J. A. LaMondia. Plant Dis. 75:1286, 1991.
