| dc.description.abstract | Meloidogyne incognita (root-knot nematode) and Rotylenchulus reniformis (reniform nematode) accounted for an estimated 7% of the cotton yield lost in Alabama in 2020 and 7.5% lost in 2021. New nematode resistant cotton cultivars and new nematicides are becoming available to help manage nematode induced yield reductions. The objectives of this study were: 1) to determine the yield potential of the new M. incognita resistance variety PHY 360 W3FE and the R. reniformis resistant variety PHY 332 W3FE in nematode infested fields and 2) to evaluate the effects of combining the new nematicide ReklemelTM (fluazaindolizine), with Vydate® C-LV (oxamyl), and the seed treatment BIOST Nematicide 100 with resistant cotton varieties on nematode population levels and cotton lint yield. In 2020 and 2021, four field trials were established in nematode infested fields. Two resistant cultivars, PHY 360 W3FE or PHY 332 W3FE, and a susceptible cultivar, PHY 340 W3FE were evaluated with and without the addition of nematicides BIOST seed treatment and Reklemel plus Vydate® C-LV in-furrow sprays applied at planting. Field trials in 2020 indicated M. incognita population levels near 45 days after planting were 63% lower on PHY 360 W3FE and 73% lower for R. reniformis on the PHY 332 W3FE compared to the susceptible PHY 340 W3FE. Nematode eggs per gram of root were further reduced with the addition of ReklemelTM and Vydate® C-LV to both susceptible and resistant varieties. In the M. incognita tests, BIOST Nematicide 100 (0.026 mg ai/seed) + the mid-rate rate of ReklemelTM (0.56 L/ha) + Vydate® C-LV (2.5 L/ha) supported the greatest lint yield (1720 kg/ha), which was increased by 357 kg/ha over the lowest yielding treatment, ReklemelTM (0.56 L/ha) + Vydate® C-LV (2.5 L/ha) (1152 kg/ha). In the R. reniformis tests, with the mid-rate of BIOST Nematicide 100 (0.026 mg ai/seed) + ReklemelTM (0.56 L/ha) + Vydate® C-LV (2.5 L/ha) supported the greatest yields (1777 kg/ha) over the lowest yielding treatment, untreated control by 488 kg/ha. Field trials in 2021 indicated that population levels near 40 days after planting for M. incognita were 82% lower on PHY 360 W3FE and 87% lower for R. reniformis on the PHY 332 W3FE compared to PHY 340 W3FE. Additionally, in 2021, nematode eggs per gram of root were further reduced 35%, 59%, and 31% after addition of Reklemel and Vydate® C-LV to PHY 340 W3FE, to PHY 360 W3FE, and PHY 332 W3FE, respectively. In the M. incognita tests, PHY 360 W3FE with BIOST Nematicide 100 (0.026 mg ai/seed) + ReklemelTM (0.56 L/ha) + Vydate® C-LV (2.5 L/ha) at a medium rate supported the greatest lint yield (14021 kg/ha), which was increased by 310 kg/ha over the lowest yielding treatment, PHY 340 W3FE + BIOST Nematicide 100 (1092 kg/ha). In the R. reniformis tests, PHY 332 W3FE with BIOST Nematicide 100 (0.026 mg ai/seed) + ReklemelTM (0.56 L/ha) + Vydate® C-LV (2.5 L/ha), the medium rate, supported the greatest yields (1591 kg/ha) over the lowest yielding treatment, PHY 340 W3FE by 583 kg/ha. Overall, planting these resistant varieties PHY 360 W3FE and PHY 332 W3FE improved yields an average of 364 kg/ha which is equal to approximately $899/ha while limiting nematode population increases; the addition of the nematicides also further increased yields 152 kg/ha of the nematode resistant varieties equaling approximately $376/ha. | en_US |
