Downey mildew of salvia splendens caused by Peronospora lamii

T. F. Wood, R. T. McMillan,Jr., W. R. Graves

Abstract


Downey mildew of Salvia splendens (Red sage) caused by Peronospora lamii is a serious problem for local commercial nursery growers of Salvia, in southern Florida. The plant pathogen P. lamii was first diagnosed and identified from a local nursery in June 2000. The conidiophores were found to be 250-600 x 8 mm; branching obscurely dichotomous, 5-7 times; branch ends 8-16 x 2-3 mm gently tapered to a point, the angle between the ends usually a right angle. The conidia were found to be 18-26 x 16-22 mm ovoid to ellipsoid, pale brown. On the host plant, the disease forms pale green to yellowish spots on the top layer of the leaves. Conidiophores and their dark conidia are found on the bottom side of the leaves as a discolored area. Peronospora lamii causes defoliation and even death to young seedlings. The discolored areas on the leaves were found mainly on those of the younger plants. The disease can be transmitted from one plant to an other, with the airborne spores causing damage to numerous plants in the locality.

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283