ISHS Acta Horticulturae 708: V International Strawberry Symposium
USDA-ARS STRAWBERRY ANTHRACNOSE RESISTANCE BREEDING PROGRAM |
| Author: | B.J. Smith |
| Keywords: | Colletotrichum acutatum, Colletotrichum fragariae, Fragaria × ananassa, disease control, fungicides |
| Abstract:
Following an epidemic of anthracnose crown rot caused by Colletotrichum fragariae, the United States Department of Agriculture, Agricultural Research Service (USDA-ARS) initiated a breeding program in 1976 to develop anthracnose-resistant strawberry cultivars adapted to the southeastern USA. A standardized anthracnose screening protocol was developed and used to evaluate over 160,000 progeny from 448 crosses. These crosses were made at the Fruit Laboratory, Beltsville, MD, and the resultant seedlings were screened for anthracnose resistance in the greenhouse at the Small Fruit Research Station, Poplarville, MS. Among the resistant seedlings field-tested in Mississippi, 1515 selections were made based on yield, fruit quality, plant habit, and resistance to leaf scorch, common leaf spot, powdery mildew, and two-spotted spider mites. Four anthracnose-resistant breeding lines and one cultivar have been released from this program, and 96 elite anthracnose-resistant selections are currently maintained. Anthracnose-resistant selections from the USDA-ARS breeding program have been used as parents in breeding programs worldwide. Research conducted at Poplarville while developing the anthracnose resistant lines has resulted in a broad range of accomplishments including the first report in the USA of the anthracnose fruit rot pathogen, C. acutatum, on strawberry. Differences in the cultural, morphological, and molecular characteristics, the infection processes, and the pathogenicity of the three causal Colletotrichum species have been documented. Studies of the effect of cultural practices on the severity and spread of anthracnose in the field demonstrated that strawberries grown in soils with high nitrogen levels are more susceptible than plants grown in soils with lower nitrogen levels or those amended with calcium nitrate. It was also determined that the use of overhead irrigation and plastic mulch in strawberry fields resulted in more severe anthracnose than when drip irrigation and straw mulch were used. Fungicide efficacy was determined by in vitro, greenhouse, and field studies, and pathogen resistance to some fungicides was detected. | |
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