Potassium and Aldicarb‐Disulfoton Effects on Verticillium Wilt, Yield, and Quality of Cotton

Optimum cotton (Gossypium hirsutum L.) yield with good fiber quality requires healthy vigorous plants throughout the season. Recently, verticillinm wilt (Verticilllum dahllae Kleb.) and K deficiency symptoms occurred during August and September in cotton grown on sandy loam soils of the Mississippi Delta. Symptoms developed earlier and faster in some caitivars compared with others. In a field study, applications of K and pesticides on verticillium wilt‐K deftciency symptoms, yield and fiber quality of ‘DES 119’ and ‘Stoneville 825’ cottons were evaluated. Broadcast application and topsoil incorporation of 112 kg K ha‐1 yr‐1 reduced verticillium wilt‐K deficiency symptoms from 12 to 7%, averaged across both cultivars, but did not affect lint yield. The root‐gall [caused by Meloidogyne incognita (Kofoid & White) Chitwood] index was reduced from 2.7 to 2.5 and from 2.7 to 2.4 by K and aldicarb‐PCNB‐ETMT [5% 2‐methyl‐2‐(methylthio)propionaidehyde‐O‐(methylcarbamoyl)oxime + 10% pentachloronitrobenzene + 2.5% 5‐ethoxy‐3‐(trichloromethyi)‐l,2,4‐thiodiazole; 0.56 + 1.12 + 0.28 kg a.i. ha‐1], respectively. Fiber strength (kN m kg‐1) was increased from 20.4 to 20.9 by K and micronaire reading was increased from 3.99 to 4.13 by aldicarb treatment. Yield, fiber quality, verticillinm wilt‐K deftciency symptoms, and root‐gall index differed between euitivars. In soil infested with V. dahliae and M. incognita, K could be used to reduce verticillium wilt‐K deficiency symptoms and root‐gall index and to increase fiber strength of cotton. Aldicarb also can be used to reduce root‐gall index. Knowing the reaction of cotton cultivars to K and to pesticides should help cotton breeders develop better adapted cultivars.