Effects of planting dates on yields and earliness of cotton cultivars no-tilled into wheat residue were evaluated in 1987 and 1988. Significantly higher yields were obtained from the earlier planting in 1987. First harvest yields of cultivars planted April 30 yielded 31% more than those planted May 14. Tillage did not influence the response of cultivars to planting on April 30 and May 14, 1987.

In 1988, paraquat at 0.52 kg/ha was applied to all wheat plots April 13. Preemergence chemicals, fluometuron, (Cotoran) at 1.34 kg/ha, and pendimethalin, (Prowl) at 1.12 kg/ha were applied to conventionally planted and no-tilled plots on April 15, April 29, or May 12. We did not obtain a satisfactory wheat kill in plots that had been no-tilled April 15.

Cotton plots that were conventionally planted April 15, yielded significantly more and were earlier maturing than cultivars no-tilled into wheat residue on April 15. Highest lint yields were obtained from Deltapine 50 that had been conventionally-planted on April 15 and April 29. Yield and maturity were essentially equal from all cultivars no-tilled into wheat on April 15 and May 12, but lint yields averaged 28% more and cotton was earlier when no-tilled into wheat residue April 29. Stands were not influenced by tillage, but plant populations were 16% larger when planted May 12. Ten randomly selected seedlings were sacrificed from each plot on June 9. Oven-dry weights of the ten epicoytls derived from Deltapine 50 plots that had been conventionally-planted April 15, April 29 and May 12 averaged 20.1 grams, 12.0 grams, and 4.1 grams respectively. Oven-dry epicoytl weights from cultivars no-tilled into wheat averaged 7.3 grams, 7.0 grams and 3.3 grams for the three planting dates, respectively.

Plant height was significantly influenced by planting dates and by cultivars, but tillage did not affect plant stature.

Below average April temperatures and very low soil moisture conditions encountered during April, May and June of 1988 may have influenced performance of cotton no-tilled into wheat stubble in April.