Impact of Velum Total on Pod and Root Damage, Peanut Root-Knot Nematode Juvenile Populations, Leaf Spot, Stem Rot and Yield of Peanut

摘要

Impact of Velum Total alone or in combination with a pegging-time application of Propulse was compared with Temik 15G/AgLogic aldicarb 15G on peanut root-knot nematode (Meloidogyne arenaria race 2) juvenile populations, leaf spot and stem rot suppression, and yield of the peanut variety Georgia-06G on an irrigated site with an established peanut root-knot population at the Wiregrass Research and Extension Center in Headland, AL. Peanut was cropped behind cotton in 2013, peanut in 2014 and 2016, and sunn hemp in 2015. A factorial design arranged as a split plot with year as the whole plot and nematicide treatment as the split plot treatments. At-plant nematicide treatments included Velum Total at 18 fl oz/A applied with a single nozzle centered over the open seed furrow in 5 gal/A spray volume, Temik 15G/AgLogic aldicarb 15G (aldicarb) at 7 lb/A applied in-furrow. A non-treated control was also included. Planting date in all study years was in early June. Propulse at 13.7 fl oz/A was broadcast to Velum Total-treated peanuts at-pegging with a tractor-mounted boom sprayer with three TX-8 nozzles per row calibrated to deliver 15 gal/A of spray volume at 45 psi and immediately watered in with 0.2 inch delivered via a lateral irrigation system. Each plot, which consisted for four 30 ft rows on 3-ft centers, were randomized in four complete blocks. The study site was irrigated as needed in all study years. Leaf spot and stem rot were controlled with a calendar fungicide program that included either four applications of label rates of Provost 433SC or two applications of Provost 433SC alternated with two applications of Abound 2SC along with a total of three applications of Bravo WeatherStik and/or Absolute. Vigor ratings on a 1 = least vigorous to 5 = most vigorous scale were recorded approximately 30 days after planting. Leaf spot intensity and stem rot incidence were recorded immediately before and after inversion, respectively. Root-knot damage to the roots and pods was rated on a 1 to 5 scale where 1 = no visible damage to 5 = 75 to 100% of roots and/or pods damaged immediately after plot inversion. Seedling vigor differed by nematicide treatment but not by study year. Greater vigor ratings were obtained with Velum Total alone or fb Propulse at-peg compared with the non-treated control, while the rating for aldicarb was intermediate between the former and latter treatments. Leaf spot intensity differed by year with the greatest disease ratings recorded in 2013 with similarly minimal leaf spotting and premature defoliation observed in 2014 and 2016. While Velum Total fb Propulse at-peg had lower leaf spot ratings than Velum Total alone as well as aldicarb and the nontreated control in 2013, similar leaf spot ratings were observed for all nematicide treatments and non-treated control in 2014, 2015, and 2016. Stem rot incidence was also lower for Velum Total fb Propulse at-peg in 2013 and 2016 when compared with the non-treated control, however, no differences in disease incidence were noted in any study year between the former nematicide program and Velum Total alone. Greater stem rot indices were reported in 2013 and 2014 for aldicarb than the non-treated control. Velum Total alone suffered less stem rot damage than the aldicarb-treated peanuts in 2013 but had similar disease indices in the remaining study years. Final juvenile populations differed by study years with the greatest counts reported in 2014, while equally low counts were noted in 2015 and 2016. Yields differed by study year and nematicide treatment with 2015 having the greatest, and 2014 and 2016 having equally low yields, when peanut followed peanut. Yield response with the Velum Total alone and Velum Total fb Propulse at-peg but not aldicarb programs was significantly higher than the non-treated control. Yields for Velum Total alone and aldicarb products were similar.