Cotton cultivar response to planting date on the Southeastern coastal plain

Farmers in the Southeast are interested in growing cotton (Gossypium hirsutum L.) following a winter cash crop or a legume cover crop. This results in a relatively late planting date. Late planting of cotton is now possible because eradication of the boll weevil in some locations has extended the effective period for boll production. Additionally, modern cotton cultivars are earlier in maturity than those previously available. Our objective was to determine the effect of five planting dates on yield, height, and fiber properties of six cotton cultivars: Coker 130 and DES 119 (early), Coker 320 and PD-3 (medium), and Deltapine 5415 and Deltapine Acala 90 (late maturing). Cotton was planted in mid-April, early- and mid-May, and early- and mid-June in 1991, 1992, and 1993. As planting date was delayed, yields decreased 2 of 3 yr, but were unaffected the third year when drought conditions limited yields. As planting date was delayed, lint percentage declined, plant height increased, fiber strength increased, fiber elongation increased, and micronaire declined. Over all years and planting dates, DES 119, Coker 130, and Deltapine 5415 had the highest yield. Deltapine 5415, a longer maturing cultivar, yielded less than the two other cultivars when planted on the later planting dates. Coker 130 had the highest lint percentage and lowest fiber strength, whereas Deltapine Acala 90, the tallest cultivar, had the lowest lint percentage and highest fiber strength. DES 119 had a lint percentage equal to that of Coker 130, as well as the highest fiber uniformity. Fiber elongation and micronaire were highest for Deltapine 5415 and DES 119. These data indicate cultivar selection is an important consideration when planting at a later than optimum date.