Weed species as hosts of Sclerotinia minor in peanut fields

Bleached stems and sclerotia were observed on winter annual weed species growing in harvested peanut fields in northeastern North Carolina in March 2001. Each field had a history of Sclerotinia blight caused by Sclerotinia minor. Symptomatic plants were collected and brought back to the laboratory for identification and isolation. S. minor was isolated and Koch's postulates were fulfilled to confirm pathogenicity of S. minor on nine weed species. They included Lamium aplexicaule (henbit), Cardamine parviflora (smallflowered bittercress), Stellaria media (common chickweed), Cerastium vulgatum (mouse-ear chickweed), Coronopus didymus (swinecress), Oenothera laciniata (cutleaf eveningprimrose), Conyza canadensis (horseweed), Brassica kaber (wild mustard), and Arabidopsis thaliana (mouse-ear cress). This is the first report of these species as hosts of S. minor in the natural environment. All isolates of S. minor obtained from the weed species were pathogenic to peanut.