Four varieties (or variety types) were tested over three row spacings in the two years reported in this study. Two barbadense varieties, S6 and S7 or OA 312, and two hirsutum varieties, DP 90 and a NM acala were planted in 30 inch, 36 inch and 40 inch row spacing environments. Optimal row spacing varied by variety over the two years but averaged over the two years, the 36 inch spacing provided the highest yields for all varieties except for the NM acatas.

A series of boll measurements were taken at several locations across the state in 1995 in an attempt to develop a yield prediction model. Measurements were taken out of two strip plot variety trials at the University of Arizona Maricopa Agricultural Center and in the Coolidge area, and also out of two commercial fields in Buckeye and Paloma Ranch over a period of approximately 2 months from peak bloom through cut-out. Data analysis revealed a best fit model that included seedcotton yield as a function of boll count, boll size, boll diameter, and heat units accumulated after planting (HUAP). A series of open boll counts were also taken from over 120 experimental units across the state within one week of harvest. The data revealed strongest relationships between final open boll counts and yield.

Cottonseed was treated with several fungicide treatments in an effort to protect the seed and seedling from disease. Seed germination and vigor was evaluated in two Arizona locations; Maricopa and Marana. Stand counts were taken on two separate dates after emergence at both Maricopa and Marana and percent emergence was calculated. Significant differences in percent emergence due to treatment were observed in both sample dates at Marana. Results at Maricopa were not statistically significant but similar trends to those at Marana were observed with treatment number 6 (no treatment) having the lowest percent emergence and treatment number 2 (combination of Nu-Flow ND and Apron TL) having the highest emergence.

Defoliation tests were conducted on upland cotton at the Maricopa Agricultural Center to evaluate rates of Ginstar and tank mixes of Ginstar with Def, Prep, and spray adjuvants. In September when temperatures were high, good defoliation was obtained 14 days after treatment using Ginstar at 0.094 lb. a. i./acre. As temperatures cooled in early October, a higher rate of Ginstar was necessary to achieve defoliation. Under very cool temperatures in late October and early November, the tank mix of Ginstar + Def generally improved defoliation over Ginstar used alone. Several adjuvants appeared to improve the effectiveness of Ginstar when temperatures were cool.

Field studies were conducted on upland cotton at the Maricopa Agricultural Center to evaluate the effectiveness of Accelerate when used in combination with other defoliants. In a September test, good defoliation was obtained in seven days using Ginstar or Dropp + Def + Accelerate and in 14 days using Accelerate + Prep. In October, under cooler conditions, no treatment provided acceptable defoliation in 14 days. In both tests, Ginstar used alone resulted in higher leaf drop percentages than Ginstar + Accelerate.

The 1995 cotton season proved to be one of the most challenging in marry years. Cold, dry spring weather delayed planting and forced many growers to replant a significant portion of their crop. The late crop then ran into extreme summer heat in July and August and very high August humidity. Daytime temperatures in excess of 120°F were reported in the low deserts in July and many locations reported extended periods with daytime temperatures above 1107. Poor fruit retention was a common grower observation as the summer heat continued The saving grace for 1995 proved to be warm and dry fall weather which assisted late season development and harvest operations.

Twelve defoliation treatments were applied to Pima and upland cotton to compare the treatment effects on percent defoliation of the plants, percent first pick values, percent gin trash and any effects they might have on fiber qualities. All of the treatments were beneficial compared to the untreated check, but differences between treatments were small.

A single field study was conducted in 1995 at the Maricopa Agricultural Center (1100 ft. elevation) to evaluate the effects of three dates of irrigation termination on yield a common Upland cotton variety (DPL 5415). Planting date was 3 April (469 HU /Jan 1 86/55° F thresholds). Following difficult establishment, crop vigor was generally low all season, with a relatively strong level of fruit retention. Three dates of irrigation termination an -1T3) were imposed based upon crop development into cut -out, with IT1 (21 August) set such that bolls set at the end of the first fruiting cycle would not be water stressed and could be fully matured. The third termination (IT3) date was 22 September, which was staged so that soil moisture would be sufficient for development of bolls set up through the first week of September. The second irrigation termination (IT2, 1 September) was intermediate to IT1 and IT3. Lint yield results revealed a 139 lb. lint/acre difference between IT1 and IT3, which was statistically significant (P < 0.05).

A single field experiment was conducted near Coolidge, AZ in 1995 to evaluate the effectiveness of a number of defoliation treatments on Upland cotton (var. DPL 5415). All treatments consisted of materials commercially available in Arizona, and each showed promise in terms of overall effectiveness. Results do provide reinforcement for current defoliation guidelines for Arizona which recommend using low rates (relative to the label ranges) under warm weather conditions, and increasing rates as temperatures cool.

All plant growth regulators and nutritional products applied to Pima S-7 cotton during bloom economically increased lint yields, with increases ranging from 80 - 261 lbs. /acre. Greatest increase was noted with Boll-Set Plus, a product that contains raised levels of calcium and zinc. Cytokin and Boll -Set Plus significantly increased yields at one location. A lint yield increase of approximately 40 lbs/acre was noted when Tech-Flo Alpha was added to Cytokin. A single application of Foliar Triggrr resulted in equal yields as two applications of the Cytokin plus Tech-Flo Alpha.