Reniform Nematode Management Linked to Variable Rate Herbicide Applications

            Rotylenchulus reniformis is one of the South's most economically damaging pests. Production aims to reduce reniform populations before planting. A strategy to reduce population before planting is to eliminate postharvest cotton re-growth as well as potential winter weeds. Herbicide applications could prove to be an effective nematode management control strategy. Tests were conducted in the greenhouse and in three field trials to evaluate the effect of herbicides on weed densities, postharvest cotton re-growth, and nematode populations, Treatments were: 1) 2, 4-D Amine 1.8 L/ha,   2)2, 4-D Amine 2.4 L/ha, 3) Dicamba 1.8 L/ha, 4) Dicamba 2.4 L/ha, and 5) control arranged in a RCBD with 4-6 replications. In the greenhouse, R. reniformis was increased for 120 days and the herbicide treatments were applied. Plant height, root/shoot dry weight, and nematode populations were determined at application and 60 DAP. Herbicides killed cotton plants reducing (P ≤ 0.05) root/shoot dry weights compared to the control. All reniform stages in the soil were reduced an average of 61% in treatments (P ≤ 0.05) compared to the control. Eggs extracted from the cotton roots were 69% lower (P ≤ 0.05) in the herbicide treatments. In the field, herbicides were applied after harvest and nematode populations were sampled at 30 day intervals.Weed populations were rated prior to pre-planting burn-down. Ratings were on a 100 point scale and data was analyzed. Weed populations were significantly lower (P≤0.1) for high rate of Dicamba compared to the control. Populations of high rate Dicamba were significantly lower compared to 2, 4-D high rate. Control ratings were 13% higher than the herbicide treatments yet not considered statistically significant. February showed no significant population difference (P≤0.1) between treatments and control. Nematode populations on DOP were also (P≤0.1) statistically lower in treatments compared to control in 2008 but not in 2009.