Two irrigation termination trials at Buckeye and two at Laveen determined that irrigation the last four days of August produced as much lint as irrigation seven to ten days later. Pima S-6 and a late planting of DP 90 after oats responded to water in the same way as the early April plantings of Deltapine 77.

Six different seed treatments and one in furrow granular treatment were used in a field with a history of black root rot, caused by Thielaviopsis basicola. The treatment was a follow-up on the study done the previous year (1). Stand counts, root lengths and seed cotton yields were taken to see if any of the treatments increased stand counts or stimulated root growth. Thielaviopsis was not isolated in the plants this year, so the effect of the fungicides on this pathogen were not evaluated. Stand counts were, however, significantly influenced by the seed treatments.

Three upland cotton varieties (Stoneville 506, Deltapine 20, and Centennial) were planted on four dates in 1987 at the Maricopa Agricultural Center and observed for flowering, boll opening, and lint yield. Results from 1985-1987 are being used to develop heat unit models for the timing of these events.

Plant growth products manufactured by BioHumaNetics, Inc. (BHN) were evaluated at the Maricopa Agricultural Center for the third consecutive year in the same field. Treatments included: 1) no fertilizers added; 2) standard fertilization used on cotton at the farm; and 3) a treatment schedule prescribed by BHN. Yields in 1987 were significantly different; the BHN treatment produced the highest yield, and the unfertilized treatment produced the lowest yield. Yields from all three treatments were substantially lower than corresponding 1986 yields.

No description available.

Wide variations existed in the performance of cotton varieties over the five planting dates among three locations over three years. However, on the average, DP 77 performed best when planted between 27 March and 22 April at Maricopa and Marana. DP 90 was best for April and early May plantings at Safford. Stoneville 506 and DP 50 were among the best for May plantings. DP 20 Stoneville 112, and DP 50 averaged best for early June plantings, except Germain 510 was superior at Safford.

Three field experiments were conducted in Avra Valley, Arizona, in 1986, to compare the lint quality of upland cotton fertilized with liquid sewage sludge with the lint quality of cotton fertilized with commercial inorganic fertilizer. Most lint quality components were similar for cotton fertilized with sewage sludge or inorganic nitrogen. Fertilization of cotton with sewage sludge tended to increase lint yield and decrease lint quality. Fertilization of cotton with sewage sludge increased vegetative growth and delayed lint maturity.

A field experiment was conducted in 1987 in Avra Valley, Arizona, to compare the plant growth and cotton lint yield from upland cotton fertilized with liquid sewage sludge with the plant growth and cotton lint yield from cotton fertilized with commercial inorganic fertilizer. Plant growth and cotton lint yields were similar when cotton was fertilized with liquid sewage sludge or inorganic fertilizers.

Research was conducted at Maricopa, AZ with EPTC (S-ethyl dipropyl carbamothioate) (1.0 lb/a) and butylate (S-ethyl bis (2-methylpropyl)carbamothioate) (2.0 and 3.0 lb/a) in 1986 and 1987 to measure the response of cotton to preplant application methods. Butylate and EPTC were applied as either a preplant incorporated or preharrow treatments. The greatest injury to cotton and poorest weed control resulted when butylate or EPTC were applied on flat ground and incorporated to a depth of 2 inches or 4 to 6 inches. Adequate weed control and minimal injury to cotton was observed when these two thiocarbamates were applied preharrow.

Research was conducted at Maricopa, AZ in 1986 and 1987 to measure cotton and weed control response to preplant applications of cyanazine (Bladex) and prometryn (Caparol). Cyanazine was applied in combination with pendimethalin and trifluralin as either preplant incorporated or preharrow treatments. Neither cyanazine or prometryn significantly reduced cotton stands or yields.