Whiteflies and Lygus bugs continue to be key pests of Arizona cotton. Some of our most popular and time-tested chemicals are still providing efficacy toward Lygus or whiteflies when used in a timely manner. However, promising new chemicals may also become available in the near future. Through research, growers can be kept updated on options for successful IPM. An experiment was conducted in order to expand our knowledge of currently available compounds and upcoming advances in insecticide development. In this experiment, 11 different compounds were tested for efficacy and duration of activity against whiteflies, Lygus, or both. Although none were active on Lygus adults, some chemicals were very effective on all stages of nymphs. Orthene® or Vydate® continue to show good results against Lygus but did not yield as high as one new compound. The best performing insecticide against Lygus was flonicamid, a novel chemistry under development by FMC. This insecticide had the best control over Lygus nymphs, was the highest yielding treatment, and required one less spray than other top performing compounds. Among newer chemistries for Lygus control is fipronil (Regent® by BASF), which performed slightly better than Vydate but not quite as effective as Orthene. Another higher-yielding regime included the use of novaluron, a novel insect growth regulator (IGR) scheduled for registration in 2005 (Diamond® by Crompton Corporation). This IGR was tested against whiteflies and Lygus bugs, but in light of yield data, Lygus efficacy should be examined more closely. None of the neonicotinoids were effective against Lygus, but several proved to be promising for whitefly control. Of the neonicotinoids tested and sprayed on threshold, dinotefuran (under development by Valent) showed good activity. The performance of spiromesifin (Oberon®, a new chemistry by Bayer) was similar to dinotefuran but needing one less spray. Intruder® out-performed all whitefly treatments, requiring only two sprays to control whiteflies season-long. Both Intruder or currently used IGRs (Knack® and Courier®) proved to be very effective against whiteflies. All insecticides in this test underwent very rigorous testing under extreme Lygus and whitefly pressures.

The integrated control concept emphasizes the importance of both chemical and biological control for pest suppression in an agricultural system. A two-year field study was conducted to evaluate the selectivity of acetamiprid for controlling sweetpotato whitefly, Bemisia tabaci, in cotton compared with a proven selective regime based on insect growth regulators (IGRs) of pyriproxyfen and buprofezin. Acetamiprid was highly effective in controlling all stages of B. tabaci compared to our untreated control and generally produced lower pest densities than the IGR regime. However, six of 14 taxa of arthropod predator were significantly depressed with the use of acetamiprid compared to our untreated control, including common species such as Geocoris punctipes, Orius tristicolor, Chrysoperla carnea, Collops vittatus, Hippodamia convergens, and Drapetis nr. divergens. Compared to other independent and concurrent studies using mixtures of broad-spectrum insecticides at the same research site, acetamiprid depressed fewer populations of predator taxa in our study, but for those taxa affected, reductions from acetamiprid were larger in many cases. In contrast, only one species was significantly reduced in the IGR regime compared with the untreated control. Predator:prey ratios were generally depressed with the use of acetamiprid compared with both the IGR and untreated control regimes. Parasitism by aphelinid parasitoids was unaffected or depressed slightly in all insecticide regimes compared with the control. Although highly efficacious for whitefly control, our results suggest that acetamiprid is a poor substitute for IGRs currently used in an integrated control program for B. tabaci in cotton.

Cotton, Gossypium spp., varying in leaf color (green vs. red), leaf shape (normal vs. okra) and leaf hairs per cm2 of leaf area were evaluated for sweetpotato whitefly (SPW), Bemisia tabaci (Gennadius) Biotype B preference. Regression analysis showed SPW adults, eggs and nymphs were significantly related to leaf hairiness. Seasonal mean numbers of SPW adults, eggs, and nymphs were high variable within and between leaf color, shape, and hairiness types. Further studies are justified since some of the cottons may be potential sources of SPW resistant germplasm.

The tillage operations conducted in a barley and cotton double-crop rotation were reduced by eliminating tillage prior to planting cotton, eliminating cultivations for weed control in cotton, and especially by eliminating tillage following cotton prior to planting barley. Data collected in 2002 and 2003 in Coolidge and Marana showed that a weed sensing, automatic spot-spray system reduced the amount of spray volume and herbicide used by 50 to 60%. Data from Maricopa in 2003 indicated that the savings can be much greater (e.g., in a treatment with thick Solum barley cover crop residues) or much less if volunteer grain germinates after grain harvest. Similar weed control was obtained with the weed sensing, automated spot-spray system compared to conventional continuous spray systems for most weed species. At Coolidge in 2002, the minimum tillage treatment with a barley cover crop produced 24% more lint than the conventional tillage system (1089 versus 880 lb/A) because more water was applied in that treatment. In 2003, the minimum tillage treatment yielded 24% less than the conventional tillage treatment (1178 versus 1539 lb/A) due to herbicide injury. There were no differences in cotton yields among the tillage systems at Goodyear in 2002 and 2003. In Marana (2002 and 2003) and Maricopa (2003), there were yield differences between treatments related to planting date, with late-planted cotton yielding less than early-planted cotton. At Marana, the cotton yields of the minimum-till and conventionally tilled treatments were not statistically different. At Maricopa, the early-planted minimum-till cotton yielded less than the early-planted conventionally tilled cotton (956 versus 1141 lb/A). The yield comparisons between conservation tillage and conventional tillage cotton production systems are not yet definitive and more research needs to be conducted. Economic comparisons between productions systems indicated an advantage for conservation/minimum tillage treatments if cotton yields were comparable.

Field experiments were initiated at sites in Marana, Coolidge and Goodyear, Arizona, in the Fall of 2001, in a cotton-based, conservation tillage project. In the 2002 cotton season, following cover and grain crops, soil and water management assessments were made to evaluate the impact of conservation tillage on surface irrigation performance. An additional site was added in the winter of 2002 at Maricopa, Arizona. Analyses included soil texture, infiltration rate and water advancement. At Coolidge, the Conservation plots had higher infiltration rates and longer advance times than the Conventional plots in 2002, 2003 and 2004. At Marana, infiltration rates were initially higher for the Conservation plots but the rates converged at the end of four hours in 2002. In 2003, the Conventional plots infiltrated about one inch more and the opposite occurred in 2004, where the Conservation plots infiltrated about 1 inch more than the Conventional. The advance times for Marana showed the water in the Conventional wheel rows to be the fastest. At Goodyear, the Conservation plots infiltrated more than the Conventional plots in 2002. This also resulted in a slower advance time for the Conservation plots. In 2003, due to tillage by the grower, treatment effects could not be compared and the site was abandoned in 2004. At Maricopa, the Conservation plots infiltrated almost 2.2 inches more water than the Conventional plots and the water reached the end of the field three hours ahead of the fastest Conservation plot in 2003. In 2004, the Conservation plot infiltrated just over 1½ inches more water than the Conventional plots with the Conventional plots having faster advance times. Seasonal irrigation water applications to each treatment were relatively equal for all the sites with the exception of Coolidge. Here, the long field combined with sandy soil made it difficult to adequately irrigate the Conservation plots. In 2002, an additional 21 inches of water was applied to the Conservation plots. In 2003, that amount was reduced to 12.5 inches. The 2004 irrigation data are not yet available. The yield data show a significant difference between years and different sites. In 2002, only the yields measured at Coolidge were significantly different with the Conservation yielding higher than the Conventional. This may have been due to the increase water application. In 2003, the opposite occurred and the Conventional plots yielded more than the Conservation plots. This may have been due to herbicide damage. At Maricopa the Conventional plot also yielded more than the Conservation plot in 2003 but there was no measured difference in 2004. The Marana site had equal yields for both treatments except for the final year, 2004, when the Conventional yielded higher than the Conservation treatment. Indications are that conservation tillage does impact irrigation performance and it may not be suitable for all locations depending on soil type and field layout.

The cotton (Gossypium spp.) plant is a true perennial with perhaps the most complex structure of all the major field crops. Plants can compensate to a large degree for environmental as well as physical conditions. Much research has been conducted to arrive at plant population recommendations that optimize the yield and quality of the crop. Research conducted in the low desert regions of Arizona suggest that optimum plant density lies somewhere between 25,000 and 50,000 plants per acre. However, cotton crops with plant densities outside of this optimal range still have the ability to yield similarly and maintain premium quality. Accordingly, a research project was conducted comparing four separate plant densities. Objectives included determining effects on yield and fiber quality. The study was laid out in a randomized complete block design with target plant populations of approximately 30K, 50K, 70K, and 90K plants per acre as the treatments. All other inputs were equal across treatments. Throughout the course of the season, plant measurements showed no distinct differences among the treatments. Height-to-Node ratios (an indicator of vegetative tendencies) remained above normal throughout the season for all populations. Fruit retention levels remained optimal throughout the season. Lint yield results revealed that treatment four (90K plants per acre) yielded significantly less that the other three treatments. No significant differences in fiber quality were observed among treatments.

A single field study was conducted during the 2004 cotton growing season at the University of Arizona Safford Agricultural Center to evaluate the effect of two plant growth regulators (PGRs) manufactured by LT Biosyn Inc. on the growth, development, yield, and fiber quality of cotton grown in the southeastern region of the state. This test was designed as a follow up study to work that was performed in 2003 on a grower cooperator site that demonstrated positive lint yield responses to the use of one of the PGRs used in this project. This was an eight treatment test involving the application of two PGRs, HappyGroTM (HG) and MegaGroTM (MG). The two formulations are intended to have different effects on plant growth and development. The HG formulation is a kinetin based product designed to enhance cell division and differentiation. The MG formulation is designed to enhance root growth early in the season. Several treatment combinations were designed to investigate varying scenarios of application of these two products alone and in conjunction with each other. The test included a control and each treatment was replicated four times in a randomized complete block design. Plant measurements were collected throughout the season to look for differences in plant growth and development. Lint yield was estimated by harvesting the entire plot and weighing the seedcotton with a weigh wagon equipped with load cells. Sub samples were collected for fiber quality and percent lint determinations. Plant measurements revealed extremely high fruit retention levels throughout the entire season with end of season levels near 75%. This high fruit retention resulted in very low vigor. Under these conditions, while lint yield was extremely high for this region (1300-1600 lbs. lint per acre), no statistical differences were observed among treatments. Fiber quality measurements also revealed no significant differences.

Two separate defoliation experiments were conducted during the 2004 growing season in an effort to evaluate the effectiveness of commercially available harvest preparation materials alone at full label rates and to also evaluate these materials at reduced rates with the addition of various synergistic chemicals designed to enhance the effectiveness of commercially available harvest prep materials. The studies were conducted at the University of Arizona Safford Agricultural Center on both Upland (cultivar DP555BR) and Pima (cultivar DP340) cotton. Plots were planted on 20 April and 27 April for the Upland and Pima, respectively. Plots were arranged in a randomized complete block design with four replications and treatments included Ginstar at recommended rates and Ginstar at reduced rates with the addition of three chemical enhancement materials (A, B, and C). Sodium chlorate was also included at a full rate and at reduced rates with the three enhancement materials. A control, not receiving any harvest prep material was also included for a total of eleven treatments. Treatments were imposed on 15 October and evaluations were made on 27 October and 4 November. Estimations on percent leaf drop, regrowth control, and open boll were made. Lint yield was estimated by harvesting the center two rows of each plot and sub-samples were collected for fiber quality analysis. Results indicated that the most effective treatment for both Upland and Pima trials was Ginstar at the full rate. Reduced rates of Ginstar in combination with the enhancement chemicals of B and C also provided good defoliation results. The chemicals that were designed to enhance the efficacy of the commercial harvest prep materials appeared to have an antagonistic affect with the sodium chlorate. Defoliation effectiveness decreased with the addition of chemicals A, B, and C to sodium chlorate. No statistical differences were detected among lint yield or any of the fiber quality parameters in any of the treatments of both the Upland and Pima trials.

A single field study was conducted at the University of Arizona Safford Agricultural Center during the 2004 season to evaluate the utilization of a feedback technique that is based upon plant growth and development to schedule applications of the new plant growth regulator (PGR) from BASF, Pentia. A simple three treatment study was constructed consisting of a control treatment (no Pentia application), a scheduled treatment (application of 16 oz/acre at first bloom regardless of plant growth), and a feedback treatment (applications based upon plant growth and development). Application decisions on the feedback treatment were made using height to node ratios (HNR) as a measure of plant vigor. Treatment applications were made on the scheduled regime on 14 July with a one time 16 oz/acre application. The feedback regime received an application (16 oz/acre) of Pentia five days later on 19 July. An additional application (16 oz/acre) was made on the feedback treatment on 3 August due to continued high HNR levels. Significant differences in plant vigor were observed post application among the three treatments as measured by end of season HNR ratios. Yield results indicated positive lint yield response to Pentia application with both the scheduled and feedback treatment producing statistically higher yields than the control. Differences between the feedback and scheduled treatments were not statistically different however a slight yield increase was observed in the scheduled treatment. The second Pentia application made to the feedback treatment was not necessary. End of season HNR measurements indicate that the additional 16 oz/acre application suppressed growth to below the average baseline for HNR. These results indicate that potential positive response to PGR applications, specifically Pentia, under conditions of high vigor.

An Upland Cotton Breeding Program was initiated in 2001 by the Arizona Cotton Growers Association (ACGA). Major objectives of the breeding program are to develop varieties that produce a superior fiber quality package, high yields, and under a wide range of environmental conditions. In 2004, the seed committee of the ACGA decided to begin an independent testing program in order to quantify the performance of chosen lines developed to date that were meeting the program’s goals. Forty one lines were chosen and evaluated in replicated small plots at two locations including Yuma and Maricopa, AZ. The final data was sorted according to lines that at both locations had a fiber micronaire of 4.9 or less, staple length of 37 or greater, strength of 30 g/tx or greater, a uniformity index of 80 or greater, and yielded in the top 25% of all tested materials. One line was identified according to this criteria, 0122-2033-304.