Development of selected tobacco cyst nematode isolates on resistant and susceptible cultivars of flue-cured tobacco

Tobacco cyst nematode (Globodera tabacum solanacearum) isolates were collec ted from 11 locations in Virginia, 3 in North Carolina, and 1 in Maryland. Isolates from each location were maintained and increased on flue-cured tob acco, Nicotiana tabacum cv K326. plants of flue-cured tobacco cultivars K32 6 (susceptible) and NC567 (resistant) were each inoculated with 6,000 G. t. solanacearum eggs/plant. Tests were conducted over one (6 weeks) or two (1 4 weeks) generations of the nematode. Shoot and root weights and the number of nematodes present within a 1-g subsample of feeder roots were recorded at completion of the tests. Nematode counts were categorized by nematode li fe stage (vermiform, swollen, pyriform, and adult). Although significant di fferences in nematode development were detected among isolates, differences were not consistent across experiments. Results indicate similar virulence among G. t. solanacearum isolates on resistant and susceptible flue-cured tobacco cultivars. Therefore, plant breeders may effectively use a single G . t. solanacearum isolate when screening tobacco germplasm for resistance.