Evaluating Genetic Resistance and Nematicides for Reniform Nematode Management in Cotton

Reniform nematode, Rotylenchulus reniformis, is an increasingly detrimental pest in cotton throughout the United States cotton belt. Field research was conducted at Damon, College Station, and Wall, TX in 2019 and 2020, and at Lubbock, TX in 2020, to assess efficacy of genetic resistance and nematicides to reduce negative impacts of reniform nematodes on cotton production. One study compared genetic resistance among root-knot resistant (RKN), reniform resistant (REN), and nematode-susceptible varieties with and without an in-furrow nematicide (fluopyram + prothioconazole). The second study compared nematicides: in-furrow aldicarb (15G), in-furrow fluopyram + prothioconazole, and foliar-applied oxamyl. In the genetics study in 2020, all three REN varieties were among the highest yielding (p < 0.002), and two of the REN varieties yielded greater (mean = 1191 kg ha^-1)  than all RKN and susceptible varieties (mean = 884 kg ha^-1) at Damon and College Station combined. Variety effects on reniform nematode populations were inconsistent; however, application of fluopyram + prothioconazole reduced nematode populations in the variety trial at College Station by 32.6% (p < 0.009). In the nematicide study at Damon, aldicarb and aldicarb + oxamyl increased yield (mean = 1019 kg ha^-1) compared to oxamyl alone (779 kg ha^-1). Nematicide treatments did not affect yield at College Station (p > 0.05), nor nematode populations at either site. Results from Wall and Lubbock 2020, as well as 2019 results, will be compared and added into the final analysis.