Association of nematodes and dogwood cankers

Dogwood canker is a serious production problem of unknown cause. From May 1985 through April 1989, cankers from 290 flowering dogwood trees in fifteen separate nurseries were sampled for nematodes. Seventy—three percent (213) of the cankers were found to contain nematodes. Panagrolaimus rigidus and Aphelenchoides spp. were reared in the laboratory on antibiotic media with Glomerella cingulata as a food source, and panagrplajimus riaidus was reared on water agar with bacteria as a food source. Repeated attempts to culture Aphelenchoides sp. on dogwood callus tissue were unsuccessful. When dogwood trees were inoculated with one or a mixture of Aphelenchoides spp. or P. rigidus, inoculation in wounds was completely callused after 60 days with no indication of canker development. Very low levels of nematodes were recovered from the inoculated trees, but P. ridigus and one Aphelenchoides sp. showed a high degree of dispersibility by occurring in treatments other than those in which they were inoculated.