Evaluating the resistance of some soybean cultivars on reniform isolates from Louisiana

Nematodes pathogenic to soybeans include soybean cyst, root-knot, lesion, lance and reniform. In 2014, loss from these nematodes was estimated at about 3% in the southern soybean producing states. In the resent years, Rotylenchulus reniformis has become a predominant species damaging to both cotton and soybeans. The use of resistant soybean varieties is the most economical and environmentally friendly management tac-tic. In research reported herein, we evaluated the resistance of known soybean cultivars to two isolates of reniform nematode from Louisiana. A single greenhouse and a single field trial were conducted. In the 60-day-duration greenhouse study, ten-day-old seedlings of each of 14 cultivars were inoculated with 10,000 mixed life stages of the nematode. At 60 days, the numbers of nematodes per 500g of soil was determined for each cultivar. Nematode population densities ranged from 953 to 101,120 vermiform life stages. Culti-vars supporting the highest population levels were MPG 4714N and R04-1268. Cultivars on which final pop-ulation density was lower than the infestation level were Dyna Grow 5575, Delta Grow 4940 and S11-20354. The field study was conducted at the LSU AgCenter, North East research station in Tensas parish, Louisiana. In this trial, fumigated (1,3-dichloropropene) and non-fumigated treatments representing 9 cultivars were employed. Nematode population data were collected at-planting, midseason and at-harvest. Application of the nematicide significantly reduced nematode population levels at all three sampling intervals. Similar to the data from the greenhouse trial, at midseason and at harvest, Delta Grow 4940 and S11-20354 had the lowest reniform nematode populations without fumigation. The cultivar R04-1268 produced the highest nematode populations in the absence of fumigation at both midseason and at-harvest. Application of the nematicide reduced nematode population significantly when compared to those without fumigation. In both the presence and absence of the fumigant, lowest yields were observed with R04-1268, MPG 4714N, and Asgrow 4534. Further studies evaluating the host status of these cultivars should be conducted using reniform isolates from multiple geographical locations