Abstract
To investigate the development of strawberry anthracnose caused by Glomerella cingulata in infested soil, we compared three inoculation methods using a conidial suspension (root dip, soil drench, and foliar spray) for differences in subsequent appearance and severity of symptoms on potted strawberry plants. Root dips and soil drenches caused sudden wilting and death with reddish brown at the base of petioles, but without typical black lesions on leaflets and petioles. These plants developed very few new roots, with areas becoming tinged with brown and black. Disease was most severe on dip-inoculated plants, followed by foliar spraying; drenching caused fewer and delayed symptoms. The fungus was frequently isolated from leaflets and petioles on plants inoculated by spraying. On root-dip-inoculated plants, the fungus was also more frequently isolated from leaflets, petioles, crowns and roots. Thus, the fungus can invade roots and crowns, as well as aerial parts. Actually, G. cingulata was isolated at a high rate from potting medium such as sawdust and peat adjacent to diseased plants that were maintained with overhead irrigation. Nursery plants transplanted into this infested media wilted; the fungus in the medium apparently served as the inoculum source. Drenching with 0.1% (w/v) solution of diethofencarb· thiophanate-methyl WP, a fungicide for anthracnose, controlled the soil infestation caused by dispersal of conidia from diseased plants.
