Martin, E. C.; Adu-Tutu, K. O.; McCloskey, W. B.; Husman, S. H.; Clay, P.; Ottman, M. (College of Agriculture, University of Arizona (Tucson, AZ), 2005-05)
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.
Rethwisch, M. D.; Suffle, R.; Reay, M.; Murphey, R. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
A field experiment was conducted to obtain data from upland cotton grown under low desert conditions to document of the effects of AuxiGro® WP and treatments consisting of AuxiGro® WP plus various foliar fertilizers on cotton yield and quality. Treatments were applied the morning of July 6, 2002, to DPL 655BR cotton that had begun bloom approximately June 28. Yields and quality data were obtained and economics calculated. AuxiGro by itself did not result in a yield increase, but did so in combination with various fertilizers. Highest quality resulted in the 8 oz/acre rate of AuxiGro + Foliar Pride fertilizer, but highest yields were documented from the 4 oz./acre rate of AuxiGro + CalMax. All treatments increased harvested value of cotton/acre when compared with the untreated check, with the treatment consisting of 4 oz./acre rate of AuxiGro + CalMax worth almost $200/acre more than the untreated check.
Rethwisch, Michael D.; Cox, Tim; Ramos, D. Michael; Luna, Manuel; Wellman, Jessica (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
A field experiment compared several rates of mepiquat chloride and Goëmar® BM86 on Upland cotton in the Palo Verde Valley during 2005 for their effects on cotton growth and yields. Leaf chlorophyll levels were significantly increased in DPL 449BR by usage of mepiquat chloride on initial samples dates after applications, and these treatments also effected cotton heights. Retention percentages and numbers of fruiting structures per plant were initially increased by treatments which contained Goëmar® BM86, although late in the season significant differences existed between Goëmar® BM86 treatments as a result of interaction with mepiquat chloride. All treatments resulted in a slight (0.01 inch) increase in fiber length as well as staple, resulting in increased lint value. The combination treatment of Goëmar® BM86 plus 12 oz./acre of mepiquat chloride had highest cotton value ($1,035/ acre), and was worth $178/acre more than the untreated check.
Clark, L. J.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
This study is a continuation of the variety trials that have been grown in the Duncan/Virden area over many years to supply yield and revenue data on premium cotton varieties for local growers. In recent years, the introduction of herbicide resistant cultivars has been particularly interesting to help clean up many weedy fields. The premium quality New Mexico Acala varieties do not, at this time, have herbicide resistance traits and have struggled to produce high enough yields to compete with the lower quality varieties that are available. Fifteen cotton varieties were tested including two 1517 varieties from New Mexico, Sierra, the newest Roundup-Ready from CPCSD, Salcot Sacala, a new acala from Arizona, and the AZ Cotton Growers variety. The rest of the entries were Roundup-Ready short to mid season varieties from Delta Pine, Stoneville, FiberMax and Paymaster. The highest yielding variety in the trial was Riata, a Roundup Ready Acala from CPCSD, with a yield of 1255 pounds of lint per acre. Sierra, ST 5599RR, ST 5303R and 1517- 99 produced around 100 pounds less lint per acre than Riata but the yields were not statistically different. Plant heights, first fruiting branches (FFB), total nodes and boll weights were measured and height to node ratios were calculated. Many differences were seen between varieties with all of these variables. The values of the variables defining the characteristics of the varieties. HVI data were obtained for fiber qualities of the lint of each variety. This data was then used to determine the value of the lint and then estimate the gross revenue produced by each variety. The highest lint value (cents per pound) was produced by 1517- 99 with 1517-95 and Riata following closely behind. The highest gross revenue was produced by Riata as a combination of the high yield and high lint value.
Dennehy, Timothy J.; Unnithan, Gopalan C.; Harpold, Virginia; Carrière, Yves; Tabashnik, Bruce; Antilla, Larry; Whitlow, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2007-08)
Bt cotton is an extremely important tool for integrated pest management in the Southwest. It has been a major factor in the current historic low levels of conventional insecticide use in cotton of this region. This is due to Bt cotton’s unprecedented efficacy against the pink bollworm, Pectinophora gossypiella, and its selectivity in favor of key natural enemies of arthropod pests. Due to the pivotal importance of Bt cotton and widespread concerns about the development of pest resistance to transgenic crops, a multi-agency resistance management program was established to monitor and pro-actively manage resistance development in the pink bollworm. This report constitutes results from the ninth year of this monitoring program. Larvae were obtained from bolls collected in cotton fields located throughout the Southwest, cultured in the laboratory, and offspring tested using diet-incorporation bioassays that discriminate between susceptible and resistant pink bollworm. A total of 11 Arizona and four California collections were successfully reared and tested for susceptibility to Cry1Ac using a discriminating concentration of 10 μg Cry1Ac/ml of diet. Susceptibility to Cry2Ab2 was estimated similarly for 12 strains from Arizona and four from California using diagnostic concentrations of 1.0 and 10 μg Cry2Ab2/ml of diet. Success of pink bollworm eradication in suppressing pink bollworm populations in New Mexico and Texas precluded successful collection of samples in those states. No survivors of 10 μg Cry1Ac/ml were detected in any bioassays of 2005 strains (n=5358). The grand mean frequency of PBW survival of 10 μg Cry1Ac/ml in 2005 was 0.000%. A susceptible culture, APHIS-S, used each year as an internal control, yielded 99.3% corrected mortality in tests of 10μg/ml Cry1Ac (n=490). All twelve pink bollworm strains collected in 2005 were highly susceptible to Cry2Ab2, based on contrasts with baseline data collected from 2001-2003. There were no survivors of bioassays of either 1.0 μg Cry2Ab2/ml (n=1,000) or 10 μg Cry2Ab2/ml (n=3425). The susceptible APHIS-S culture had 82.5% corrected mortality in tests of 10 μg/ml Cry2Ab2 (n=200) and 100% mortality in tests of 10 μg/ml Cry2Ab2 (n=120). Field evaluations of efficacy of Bt cotton were conducted by the Arizona Cotton Research and Protection Council in adjacent pairs of Bt and non-Bt fields at 44 Arizona locations. Statewide, large pink bollworm larvae were found in an average of 15% of non-Bt bolls sampled from borders of refuge fields. This was on the low end of the range of infestation levels observed in refuges during the past decade. Bolls from adjacent Bt cotton (Bollgard™) fields yielded an average of 0.28% infested bolls. This value was down slightly from the previous year. Over 70% of the pink bollworm recovered from collections in Bt fields were from bolls that did not express Bt toxin. We conclude that there was no indication of problems with pink bollworm resistance to Cry1Ac or Cry2Ab2 at the locations sampled in 2005. Moreover, Bt cotton continued to exhibit exceptional field performance in Arizona.
Fournier, A.; Ellsworth, P. C.; Barkley, V. M. (College of Agriculture, University of Arizona (Tucson, AZ), 2007-08)
In the Western U.S., Lygus spp. (Hemiptera: Miridae) can cause major losses to cotton, vegetables, seed crops, and a variety of other crops. However, the economic impact of this pest remains largely undocumented in most crops. Two major data sources were used to quantify the economic impact of Lygus in lowdesert upland cotton production in Arizona: a statewide Pesticide Use Reporting (“1080”) database and an annual “Cotton Insect Losses” (CIL) survey of cotton Pest Control Advisors (PCAs). Both data sources include information on the target pest for insecticide applications, making it possible to single out Lygus control efforts. PUR data, based on information submitted by applicators to the Arizona Department of Agriculture, provides quantitative information on a high proportion of Lygus applications in cotton, but is incomplete, since not all types of applications require reporting. These data are complemented by information from the CIL survey to provide a more complete picture, based on direct responses from PCAs about their pest management practices. While the 1080 database is very useful in documenting a high proportion of Lygus insecticide use in cotton, by definition, these data on their own cannot provide good estimates of statewide behaviors with respect to Lygus management. In contrast, this is exactly what the Cotton Insect Losses survey is designed to do. As indicated by 1080 data and CIL data from 2001 to 2005, Lygus is the most important pest in Arizona cotton most years, based on application*acres of all foliar insecticides. Other key pests by this measure are sweetpotato whitefly, Bemisia tabaci Genn., and to a lesser extent pink bollworm, Pectinophora gossypiella (Saunders). Whitefly is the most important Lygus co-target, when applications are aimed at controlling more than one pest. The most commonly used foliar materials against Lygus in Arizona cotton are acephate, endosulfan and oxamyl, and they are typically used at about 90% of maximum label rates. About 80% of Lygus applications occur between mid-July and late-August. Average spray intensity (based on average sprays per acre) was calculated independently using the CIL and 1080 data sets and compared. For every year except for 2004, the CIL data estimates a somewhat higher insecticide use against Lygus . Several reasons for this discrepancy were identified, including less than 100% pesticide use reporting on 1080s; differences in the insecticides included in the estimates (top three active ingredients only for 1080 estimate, all insecticides for CIL estimate); and differences between how the two datasets apportion a single spray event among multiple pest targets. The intensity of Lygus management varies by county, based on 1080 data and county-level information on cotton acreages. Pinal county, which has the most cotton acres, shows the highest sprays / acre of the top three active ingredients to control Lygus . Analysis of 2005 1080 data at the section level indicates a relationship between the proportion of sections where cotton is grown in a Township - Range and spray intensity for Lygus control. Growers in Township - Ranges with a low proportion of cotton sections (10–15%) tend to make more sprays per field to control Lygus . However, Township – Ranges with the lowest and highest proportions of cotton sections (<10% and >90%) tend to show trends of lower spray requirements for Lygus control. These data suggest the possibility that landscape factors can influence Lygus populations at the local level, although more research in this area is needed. Lygus is perhaps the most significant economic pest of Arizona cotton. Cotton Insect Losses survey data indicate that a high proportion of cotton insect pest management efforts are directed toward Lygus control. Up to 40% of foliar insecticide sprays target Lygus , for about one third of the foliar insecticide budget for growers most years. Despite these control efforts and associated costs, Lygus are consistently listed in the CIL by survey respondents as the most damaging insect pest of cotton, accounting for more than 50% of insect-related yield loss most years. These two different and complementary data sets provide important baseline information on the current status and economic impact of Lygus in Arizona cotton, which will be useful for measuring changes in Lygus impact and control practices over time. A number of factors could potentially impact these practices in the future including (1) the introduction of new selective chemistry for Lygus control; (2) the introduction of transgenic control options for Lygus ; and (3) landscape-level changes that can have area-wide impact on Lygus management in cotton and other crops. These data underscore the need for continued research to develop effective, selective tools for improved Lygus management in cotton, and to integrate these into effective IPM programs. Data documenting a pest’s economic impact provides a rationale for funding to support critical IPM research and education. There is a need to similarly document the economics of Lygus management in other crops including vegetables, seed crops, and alfalfa, and the impact of landscape-level factors on Lygus management in a variety of crops.
Adu-Tutu, K. O.; McCloskey, W. B.; Husman, S. H.; Clay, P. A.; Ottman, M. J.; Martin, E. C.; Teegerstrom, T. (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
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.
Husman, S.; White, K. (College of Agriculture, University of Arizona (Tucson, AZ), 2005-05)
Upland cotton advanced strains and commercial check varieties were evaluated in replicated field studies at three locations in 2004. The test sites include the AZ locations of Safford, Maricopa, and Yuma. Eight seed companies submitted a maximum of ten advanced strain entries per location. Three commercial check varieties were used at all three sites, and included ST5599BR, DP449BR, and DP448B. Data collected included final plant heights, yield, and fiber quality. The research is conducted in order to develop public unbiased performance data of genetic materials that have moved to the advanced stages of testing and are being considered for commercial release. The data have historically been used to add to seed company databases and assist with commercial release decisions.
Husman, Stephen H.; McCloskey, William B.; Clay, Patrick; Norton, Randy; Norton, Eric; Rethwisch, Mike; White, Kyrene (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
Twin-line (two seed lines 7.25 in apart per bed) and conventional single seed line per bed cotton production systems were compared at 16 sites across Arizona and Blythe, Ca. in 2002. The twin-line system produced more lint than the conventional single-line system at 4 of 16 locations; the yields of the twinline and single-line systems were 1273 and 1186 lb/acre, 1572 and 1461 lb/acre, 1478 and 1290 lb/acre, and 1309 and 1210 lb/acre, respectively, at the Grasty, Ramona, Rovey, and Wells sites, respectively. There were no significant differences in yield or fiber micronaire in 7 of the 16 experiments. The twin-line system produced less lint than the conventional system at 5 of 16 locations; yields of the twin-line and single-line systems were 2019 and 2189 lb/acre, 1400 and 1489 lb/acre, 1537 and 1845 lb/acre, 1065 and 1200 lb/acre, and 1271 and 1431 lb/acre, respectively, at the Chaffin (75K), Cooley, Hull, Papago, and Wakimoto sites, respectively. Fiber micronaire was reduced in five experiments; the micronaire values were 4.25 and 4.73, 4.46 and 4.78, 4.60 and 4.85, 4.76 and 4.98, and 4.93 and 5.15, in the twin-line and single-line systems, respectively, at the Rogers, Papago, Grasty, Hull, and Perry sites, respectively. Research will continue in 2003 in order to develop system comparison data for multiple years and to elucidate the reasons for the variable results measured in the 2002 cotton season.
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