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Effect of fungicide and nematicide seed treatments alone and in combination on cotton stand and yield

Jason Woodward: Texas A&M AgriLife Extension Service

<div>Seed cost is the largest expenditure producers have when planting cotton (<em>Gossypium hirsutum</em> L.). While all commercial seed comes with a broad-spectrum base fungicide package, many of the premium products sold contain additional fungicide or nematicide/insecticide treatments. Producers often question the need for such products. Field studies were conducted in 2016 and 2017 to compare a non-treated control (TRT 1), a nematicide/insecticide seed treatment (TRT 2), a base fungicide seed treatment (TRT 3), and the combination of the base fungicide seed treatment and the nematicide/insecticide seed treatment (TRT 4) under two seeding rates. Stands for TRT 1 and TRT 2 were similar within a seeding rate and across years. Stand improvements over TRT 1 across the two years and two seeding rates ranged from 20 to 52% and 26 to 68% for TRT 3 and TRT 4, respectively. Similar trends were observed for lint yield when combined across years and seeding rates. Yields for TRT 1 and TRT 2 did not differ. The addition of a fungicide treatment increased yield by 214 kg ha-1 over the control, whereas, including a nematicide/insecticide with the fungicide treatment improved yields an additional 93 kg ha-1. This response was in the absence of nematodes or thrips, suggesting a synergism exists between the fungicide and nematicide/insecticide seed treatments evaluated.</div>