During 1987, a sequential sampling plan for pink bollworm eggs was field-tested in eight 40-acre fields in the Palo Verde Valley, CA. Final analysis of the sequential procedure, including the time necessary to collect and check all bolls, required an average sampling time of 16 minutes/field, approximately a 70% savings over the fixed sample size of 160 bolls/field. Using the sequential plan, the number of bolls examined averaged 46.75/field. The sequential sampling plan error rate for making no-treat recommendations when a field actually required treatment (i.e., actual egg infestation 6%) averaged only 6.4% throughout the season. A final sequential sampling chart, based on the field validation data, is presented.

A process- oriented simulation model of pink bollworm population dynamics in commercial cotton has been developed. The model, written in FORTRAN, is driven primarily by temperature and crop phenology. In addition to key ecological parameters, the model incorporates the impact of multiple insecticide applications. The model is presently being validated and modified for use as an on-line management tool.

Pink bollworm egg -larval survivorship in insecticide -treated fields averaged (± SE) 19.8% (± 2.3) for the F2 and F3 generations developing during the primary boll producing time of the year (July and August). These observations have been useful in developing a simulation model of pink bollworm population dynamics.

Growth and development was studied in the beet armyworm (BAW), Spodoptera exigua, reared on cotton seedlings at high (650 ppm) or ambient (325 ppm) carbon dioxide (CO₂) levels and at 2 fertilizer levels. Under high fertilization, female BAW reared on CO₂-enriched seedlings weighed significantly less (873 mg) than controls (101.0 mg) and had a significantly longer developmental time (14.2 vs. 12.4 days for controls). Male BAW followed the same pattern but the data were not statistically significant. Combined (male & female) survival rates for BAW reared on CO₂-enriched cotton seedlings on a high fertilizer level were 19.1 compared to 41.6 % for controls; more females survived than males by a significant ratio of 2:1.

Plant derived oils (cottonseed and soybean) in greenhouse and field studies were promising for sweet potato whitefly, Bemisia tabaci (Gennadius) control. Cotton seedlings treated with oil in the greenhouse repelled whiteflies up to 7 days and high mortality of treated larvae, pupae and adults occurred. In the field, application of crude cottonseed oil to cotton with high air-blast, ground spray equipment suppressed whitefly populations thoughout the season.

The sweet potato whitefly, Bemisia tabaci (Gennadius) continues to be a serious pest of cotton and an important vector of several virus diseases of fall vegetables. In our search for resistant germplasm, we counted adult whiteflies on cotton cultivars and breeding stocks in AZ and Israel. At Maricopa (MAC), seven of 19 cottons had significantly fewer whiteflies than the check, 'Stoneville 825'. Five of the seven were okra-leaf and two were normal-leaf cottons. In another experiment at MAC, an okra-leaf cotton did not have fewer whiteflies than a normal-leaf one. At several locations in Israel, the okraleaf cotton, BD-12, had significantly fewer whiteflies than a number of normal-leaf cottons.

A survey of agricultural pest control professionals showed that certain compounds have consistently been recommended to control cotton pests for more than 40 years. Over that same period, the number of preferred materials available for recommendation has greatly increased. Other trends are toward greater use of compounds using lower application rates and biological insecticides.

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.

No description available.

Foliar applications of zinc as a chelate or sulphate with ammonium sulphate to plots of cotton resulted in beet armyworm infestations with leaf damage that was 2.3 to 3.1 times greater than that in control plots.