Occurrence and Control of Ditylenchus dipsaci Associated with Dieback of Phlox subulata. L. S. Schnabelrauch, Department of Horticulture, Michigan State University, East Lansing 48824. G. W. Bird, Department of Entomology and Department of Botany and Plant Pathology, F. F. Laemmlen, Department of Botany and Plant Pathology, and K. C. Sink, Department of Horticulture, Michigan State University, East Lansing 48824. Plant Dis. 65:745-748. Accepted for publication 5 January 1981. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-745.

Foliage dieback can be widespread in commercial production of Phlox subulata in Michigan. Symptoms are consistently associated with high population densities of an onion-phlox hybrid race of Ditylenchus dipsaci, the bulb and stem nematode. Only limited tolerance to D. dipsaci was detected in field and greenhouse evaluations of commercial cultivars of P. subulata. Applying aldicarb to the soil at planting or oxamyl to the foliage after planting significantly reduced field populations of D. dipsaci and alleviated foliage dieback of P. subulata. Control of D. dipsaci was sustained during the first growing season, throughout winter storage, and for most of the second growing season.