Efficacy of PHY367WRF in Root-Knot Nematode Infested Fields.

Root-knot nematodes (Meloidogyne incognita) are a serious pest of cotton with yield losses ranging from 10% to 25%. Phytogen Seed Company has developed an early maturing cotton variety, ‘PHY367WRF’, that greenhouse studies indicated as moderately resistant to root-knot nematodes (RKN). The objective of this study was to evaluate the efficacy of PHY367WRF as compared to Telone fumigation, Temik in-furrow and Avicta seed treatment nematicide treatments in RKN-infested fields. Prior to planting, an 8-row strip was treated with Telone, Temik was applied in-furrow at planting to another strip and a third strip was left untreated for nematodes. The design was a split plot with seed treatment whole plots and variety subplots replicated six times and arranged in three adjacent strips.

PHY367WRF had less severe galling and fewer RKN in the soil than did the susceptible check, ‘PHY375WRF’. Both Telone and Temik reduced the galling of both varieties, but the galling of PHY367WRF without any treatment was as low as PHY375WRF with Telone. Averaged over the three locations and all treatments, PHY367WRF had 72% fewer RKN in the soil at the end of the season. 

Despite significant differences in root galling and ending RKN levels, differences in yield were observed only at Clarkton, MO. The difference in yield between varieties was not significant in the Telone strip, but it was highly significant in the other two strips with PHY367WRF yielding 19% more than PHY375WRF in the untreated strip.

This study indicated that the moderate RKN resistance in PHY367WRF was equivalent to Telone and Temik treatments in reducing galling and it surpassed Telone in reducing RKN levels in the soil. There was only negligible benefit to treating PHY367WRF with any nematicide treatment. Avicta had no significant effect in this study, but nematicide seed treatment may be useful to enhance the durability of resistance.