Rooted cuttings of Chapman's rhododendron (Rhododendron chapmanii) in soilless medium were challenged with inoculum of the soi1borne fungus, Phytophthora cinnamomi (Rands). A portion of the plants received a soil drench of Subdue 2EC (metalaxyl) at 0.16 ml/L (2.0 oz/100 gal) at 2 month intervals. Chapman's rhododendron was highly susceptible to P. cinnamomi, but five of six plants treated with Subdue did not develop symptoms of Phytophthora root rot. In the one plant which developed root rot symptoms, P. cinnamomi was recovered in culture.
Paper No. 11941 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, 27695-7643. Technical assistance by Billy I. Daughtry, Department of Plant Pathology, North Carolina State University, Raleigh, NC, is gratefully acknowledged.
3Professor, Department of Horticultural Science.