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An experiment was conducted on sandy loam soils at two locations in North Carolina during 1990. The objective was to determine if in-furrow application of the organophosphate insecticides Disyston (disulfoton) and Thimet (phorate) alter cotton response to Scepter (imazaquin) or Pursuit (imazethapyr). The experimental design was a split-plot with four replications. Main plots were rates of Scepter and Pursuit (0.0, 3.6, 7.3, 14.5, and 28.6 g ai/A) applied preplant incorporated; subplots were 0.75 lb ai/A of Disyston, Thimet, and Temik (aldicarb) applied infurrow. All plots received a preplant incorporated application of Prowl (pendimethalin) and a preemergence application of Cotoran (fluometuron). Plots were maintained weed-free. Other cultural practices were normal for cotton production. Significant herbicide by insecticide interactions were not observed for any variable recorded, indicating response to both herbicides was similar regardless of the in-furrow insecticide used. There were significant main effects of insecticides and herbicides. Temik was found to be the superior insecticide. The insecticides did not affect stands, yield or fiber quality, but did affect cotton maturity measured as percent open bolls at the normal time for defoliation and as percent of total yield in the first picking. maturity was delayed with Disyston and Thimet compared to Temik. Plant mapping revealed a lower percentage of the total boss set on positions one and two of sympodia arising from nodes 4 through 10 with Disyston and Thimet as compared to Temik. This is thought to be at least partially due to more thrips damage to plants receiving Disyton and Thimet. Plants receiving Disyston and Thimet compensated by setting more bolls ar nodes greater than 10. Cotton injury increased as the rate of Scepter or Pursuit increased while the number of surviving cotton plants decreased as the herbicide rates increased. At the location with better growing condition and earlier maturing cotton, Pursuit had no effect on cotton yield. Scepter at 14.5 and 28.6 g/A reduced yield 20 and 40%, respectively. At the other location with less favorable growing conditions, both herbicides at rates of 7.3 g/A or greater reduced yield. Cotton maturity declined as herbicide rates increased. Both herbicides at rates of 7.3 g/A or greater reduced the percentage of bolls set on nodes 4 through 10 |
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©National Cotton Council, Memphis TN |
Document last modified Sunday, Dec 6 1998
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