VIEW ARTICLE

Ecology and Epidemiology

Epidemiological Studies of Blueberry Anthracnose Disease Caused by Colletotrichum gloeosporioides. J. S. Hartung, Graduate research assistant, Department of Agriculture, Michigan State University, East Lansing, MI 48824; C. L. Burton(2), and D. C. Ramsdell(3). (2)Research plant pathologist SEA-AR, U.S. Department of Agriculture, Michigan State University, East Lansing, MI 48824; (3)Professor, Department of Botany and Plant Pathology, Michigan State University, East Lansing, MI 48824. Phytopathology 71:449-453. Accepted for publication 23 September 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-449.

Epidemiological studies of blueberry anthracnose disease caused by Colletotrichum gloeosporioides were conducted in a commercial highbush blueberry field (cultivar Jersey) at Grand Junction, MI, in 1978 and 1979. Conidia of C. gloeosporioides were collected in rainwater runoff from diseased bushes from the bud swell through the harvest stages of growth. Conidia were associated with diseased fruiting wood, blossoms, and rotting fruit. Maximum numbers of conidia appeared to coincide with probable natural fruit infection periods as predicted by in vitro conidial germination studies. Such incidents occurred from the green fruit through the harvest growth stages. Inoculation of swelling flower buds, blossoms, and immature fruit, both on mature branches of cultivar Jersey bushes in the field and on potted 3- to 4-yr-old bushes (cultivars Bluecrop and Berkeley), with 10⁶ conidia per milliliter sterile distilled water, resulted in apparently healthy fruit that later developed a rapid anthracnose decay after harvest. Inoculations performed prior to and during bloom also caused a severe blossom blight. The pathogen overwintered in blighted fruiting wood which it entered via blighted blossom clusters or, perhaps, rotting fruit pedicels.