When other means fail to avoid damaging levels of an insect pest population, chemical control becomes necessary. Chemical control is a variable farm input which should be optimized to reduce economic damage by the pest while maximizing profit and minimizing exposure to secondary pest outbreaks, pest resurgence, and risks of insecticide resistance. To best balance these needs, a grower or PCA needs the best information possible for selecting and timing chemical controls. This study examines the array of Lygus chemical control options currently available as well as experimental compounds that may or may not be available in the future. While identifying the best chemical controls is the major objective of this study, insights into proper timing and duration of control are also discussed. In short, there are few, yet effective, Lygus insecticides available to growers currently. However, with proper rates and timing, significant yield protection can be achieved with Orthene® or Vydate®. To a lesser extent, Thiodan® (endosulfan) was also effective against Lygus, though higher rates than used in this study may be necessary to achieve acceptable control. The use of mixtures did not enhance control of Lygus over our two standards (Orthene or Vydate). Newer compounds were also studied; however, Mirids (plant bugs) are not worldwide targets for development by the agrochemical industry. Thus, most new compounds are effective on some other primary pest (e.g., whiteflies, boll weevil, thrips, aphids), and control of Lygus is merely a potential collateral benefit. Of these, the chloronicotinyls (e.g., Provado®, Actara®) were not practically effective against Lygus hesperus, in spite of their existing or pending labelling. Their labels are based on demonstrated efficacy against a related species present in cotton outside of the West (Lygus lineolaris). One compound shows excellent promise as a Lygus control agent, Regent® (fipronil). Under development by Rhône- Poulenc, this insecticide provides as good or better protection against Lygus than our best materials. In a system demanding multiple applications to control chronic Lygus populations, Regent could be key to the development of a sustainable use strategy that does not over rely on any single chemical class. None of the insecticides tested significantly controlled adult Lygus, except after repeated use and time. Even then, this effect was likely the result of generational control of the nymphal stage which thus produced fewer adults over time. Nymphal control was excellent for Orthene, Vydate, and Regent. Yields were up to five times higher in the best treatments relative to the untreated control. Other effects were also documented for the best treatments which have additional positive impact on grower profitability: shorter plants (better defoliation), higher lint turnouts, less gin trash, and a lower seed index.

Temik 15G (6 lbs/acre) or Thimet 20G (8.2 lbs/acre) granular insecticides were applied to 40 inch rows in furrow at planting to cotton growing in Parker Valley, AZ. Moderate thrips pressure (0.5-1.5 thrips/plant) was experienced for the first eight weeks after planting and granular insecticide application. Temik provided better thrips control than Thimet for the first seven weeks after planting this study. Thrips control was similar for the two insecticides beyond eight weeks after planting. Temik application resulted in higher fruit retention levels measured up to 10 weeks after planting, compared to Thimet. However, fruit retention levels measured from 12 to 16 weeks after planting were similar for both Temik and Thimet when cotton plants compensated for early season square losses caused by thrips feeding.

A field demonstration was conducted in Mohave Valley to compare cotton morningglory control programs that combined the use of over the top herbicides Roundup Ultra on Roundup Ready cotton (Deltapine 436 RR) or Staple on non-transgenic cotton (SureGrow 125) with and without precision cultivation.

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 three Arizona locations; Maricopa, Marana, and Safford. Stand counts were taken after emergence at all three locations and percent emergence (PEM) was calculated. Significant differences in percent emergence due to seed treatments were observed in the both sample dates at Marana. Maricopa and Safford showed no statistically significant differences due treatment.

Two upland cotton varieties (Deltapine 5415 and SureGrow 125) were subjected to various seed fungicide treatments to determine seedling emergence and vigor in a Mohave Valley field prone to Rhizoctonia infection of cotton seedlings. During 1998, cotton seedlings in this field exhibited symptoms associated with Rhizoctonia, Pythium, and Thielaviopsis fungi. Of the treatments examined in this study, Baytan+Thiram+Allegiance or Baytan+Ascend+Allegiance cotton seed treatments provided superior seedling disease protection. The Protégé+Allegiance fungicide treatment provided superior seedling disease protection when applied to Deltapine 5415 cotton seed, however seedling disease suppression was poor when the same treatment was applied to SureGrow 125. The Vitavax-PCNB+Allegiance and NuFlow M+Maxim+Apron were the least effective fungicide seed treatments examined in this study.

Four varieties each of Long Staple and Short Staple cotton were tested over five and four dates of planting, respectively, in this study. The first date of planting for the Long Staple cotton was the 18th of March and for Short Staple cotton the 1st of April. The latest planting was May 13th. Cultivars of differing maturities were tested for both long and short staple cotton to determine their optimal planting time. Many agronomic parameters were evaluated to determine the effect of different planting dates

Two field experiments were conducted near Marana and Coolidge, AZ in 1999 to evaluate the effectiveness of a number of defoliation treatments on Upland (var. DP 33b and AP 6101) cotton. All treatments consisted of materials commercially available in Arizona. Results reinforce general recommendations regarding the use of low rates (relative to the label ranges) under warm weather conditions and increasing rates as temperatures cool. Defoliation treatments of Ginstar alone did a satisfactory job of defoliation and regrowth/topgrowth contol and were very similar to treatments including Prep or Integrate. Adding Prep or Integrate to Ginstar in this experiment did not improve defoliation or topgrowth control.

Weekly production advisories and weather updates are now available from the Internet. Nineteen location-specific advisories are developed each Monday morning and then transferred to the Main AZMET Internet Web Page located at URL address http://ag.arizona.edu/azmet. To retrieve advisories or updates from the Internet users must 1) log on to the Internet using the procedures required by your Internet service provider; 2) enter the URL for the Main AZMET Web Page; 3) move to the Cotton Advisory sub-page; and 4) select the advisory or update of interest. Advisories for the most recent week, this year to date, and all of 1999 are available at this Internet address.

Each year the University of Arizona conducts on-farm variety trials across the state to evaluate the performance of upland cotton varieties. These tests provide many segments of the industry with unbiased, independent data on the performance of varieties from several seed companies when tested side-by-side under typical production practices. Ten trials were planted in the cotton producing areas of the state, ranging from Wellton in Yuma county to Kansas Settlement in Cochise county. Seed companies entered a maximum of two varieties per location resulting in eight to thirteen commercially available varieties per test. The results show that many varieties performed well at several locations, indicating good adaptation to Arizona conditions.

A field study was conducted in 1999 at the University of Arizona Marana Agricultural Center (1,974 ft. elevation) to evaluate the effects of three planting dates on yield and crop development for eight Upland varieties. Soil temperature effects associated with date of planting and method of planting (dry or wet planting) were also evaluated in relation to soil temperature at the depth of seed placement. Planting dates ranged from 28 April to 20 May and 821-1157 heat units accumulated since Jan 1 (HU/Jan 1, 86/55o F thresholds). Lint yields generally declined with later dates of planting for all varieties. Soil temperatures associated with the dry planting method, which requires a water-up irrigation, experienced much wider diurnal variations, had slightly lower mean temperatures, and were more strongly coupled to ambient air conditions. Thus, dry planting methods impose more potential risk in terms of seedling stress. Overall, crop growth and development patterns or yield results were not significantly different between the planting methods. Either method can provide satisfactory results if managed appropriately.