We need efficient sampling methods, appropriate thresholds based on a well -defined Lygus density yield relationship, and knowledge of the most effective chemical controls available. Insecticides were evaluated for control of Lygus at 5 'at risk' grower locations, as well as at 4 other experimental sites. Application methods were different at each site according to grower practice or experimental protocol (5-20 GPA; by ground, air, or electrostatically-assisted ground sprayers). Evaluations were made based on the number of Lygus per 100 sweeps. Orthene®, Vydate® or to a lesser degree, Monitor® used alone and at high rates appeared to perform adequately at all sites. Both rates of Regent™, a new chemistry under development by Rhône- Poulenc, provided excellent levels of control comparable to Orthene in a high density test. In this same test, none of the experimental and registered pyrethmids provided adequate control when used alone. Thiodan®, when mixed with Mustang®, provided some level of control. Over all tests measured for yield, a positive net return was possible with no more than 2 sprays of solo materials which yielded between 0.3 and 0.5 bales/A more than untreated comparisons or between $51-130/A net return. Also, at one site where yields were in excess of 4.2 bales/A, optimum planting and fruit-set prior to heavy Lygus pressures and monsoon-associated heat stress was an important cultural tactic for avoiding losses to Lygus - the check yielded over 3.7 bales /A! As seen at grower sites and confirmed in experimental studies, solo compounds, at appropriate rates, performed as well or better than any combination tested. And, mixtures at this time do not appear to provide any additive, synergistic or economic benefits in the control of Lygus. Combinations, unless indicated by another pest problem (e.g., whiteflies), are not "worth it," and needlessly expose the grower to larger input costs, "empty" applications, and higher risks of resistance, pest resurgence, secondary pest outbreaks, and phytotoxic effects by insecticides.

Arizona cotton growers were surveyed regarding the importance of Integrated Pest Management (IPM) and Best Management Practices (BMP). Telephone surveys reached 249 individuals over a ten-day period. The survey asked growers to rate the importance of each IPM/BMP tactic on a scale of 1 (not important) to 5 (very important). Of the 14 practices /tactics listed for IPM, eight had significant chi-square values. These included scouting, crop rotation, variety selection, petiole testing for nitrogen, pheromone use, equipment calibration, and stalk destruction. Of the eight practices /tactics listed for BMP, six had significant chi -square values. These included crop rotation, timing and splitting of nitrogen applications, petiole testing, time of planting and variety selection for specific suppression (Bt cotton). In general, whether it was an IPM, weed management, or a BMP practice/tactic, the growers scored a majority of the tactics as important. It could be inferred from the growers' responses that they agree that the practices listed as important were, in fact, important grower practices.

Whiteflies remain a threat to production of cotton in Arizona. Looking at a series of commercial-scale trials, levels last season were delayed compared to previous years, but at higher densities than in 1995, an outbreak year. Efforts must be expended to optimize insect growth regulator (IGR) use and integrate these tactics with other aspects of crop and pest management. Broad spectrum insecticide use prior to treatment for whiteflies with IGRs alters the ecology of the system. Whitefly densities consistently increased after disruption with a Lygus insecticide relative to Lygus -untreated areas. While Lygus control is a production imperative, guidelines are presented for minimizing the impact of this disruption. The modes of action for the two IGRs differ substantially and result in subtle changes in population age structure and dynamics. The consequences of these changes impact natural enemies and should be noted by producers when selecting an IGR or monitoring populations after treatment. Re- treatment after initial IGR sprays depends on many factors. While apparently similar levels of suppression are possible when only one IGR is used, regimes using both available IGRs resulted in the fewest number of damaging large nymphs late in the season, just prior to defoliation. Conventional insecticides rotated according to pre-IGR introduction guidelines (`95IRM') also suppressed populations significantly and comparably to IGR regimes until late in the season. Then, whitefly densities rose aggressively just prior to defoliation and pyrethroid susceptibility was significantly reduced in the 951RM regime. Full adoption of IGR -based technology along with `Bt' cotton allows growers to better manage whiteflies with fewer disruptions which can lead to secondary pest outbreaks, pest resurgence, and insecticide resistance.

Field studies were conducted in 1997 to evaluate strategies for management of whitefly (Bemisia tabaci). We evaluated the effects of different insecticide regimes (conventional and insect growth regulators [IGR]) on the abundance of native parasitoids and predators associated with whitefly in Arizona cotton. Immature parasitoids were most abundant in untreated control plots and there was little difference among insecticide regimes. Percentage parasitism was low overall (< 30 %), but was highest in Knack plots and lowest in untreated control and Applaud plots. Predator populations were lowest in plots treated with conventional insecticides, and there were several instances where weekly or season -long populations of several predator species/groups were slightly depressed in IGR plots compared with the untreated check. Overall, results are encouraging and indicate that use of IGRs helps to conserve populations of native natural enemies.

Whitefly populations in this trial were abnormally low relative to previous years experiences. M-25 provided excellent whitefly control and was equivalent to the commercial standard (Knack followed by Danitol + Orthene). However, there is some question concerning its adult activity late in the season, when it appeared to be weaker than Danitol + Orthene and Capture + Curacron. At low whitefly populations Thiodan tank -mixed with Knack appeared to extend control over Knack alone.

Bemisia argentifolii Bellows and Perring populations were higher on Pima S-7 cotton compared with DPL 50 cotton. Higher numbers of mature open cotton bolls occurred earlier for DPL 50 compared with Pima S-7. Also, numbers of open bolls for DPL 50 peaked 8 to 14 days before Pima S-7 and decreased dramatically by 15 September reflecting termination of the first fruiting cycle in August In contrast the indeterminate fruiting pattern of Pima S-7 showed that numbers of open bolls per week declined gradually after the peak without a clear cut termination occurrence. About 95 and 80% of the open cotton bolls, of the Deltapine and Pima S-7 cottons, respectively, occurred by mid- September. This suggests that defoliation timing and early harvest can be important management tools to avoid sticky cotton. For upland cotton, extending the cotton season after 95% of the crop matured (≅ 15 September) resulted in development from non - sticky cotton to lightly- sticky cotton within 21 days following the occurrence of increasing whitefly populations after 15 September. Later fruiting and lack of a distinct end of the first cotton fruiting cycle probably precludes using early defoliation for long -staple Pima cotton. At harvest, thermodetector counts for all weekly harvests were greater than amounts found in lint for randomly selected 20 boll samples; and samples from all cotton picked from 4 m of row. This probably occurred because weekly picked cotton escaped rainfall and exposure and other weathering, in 1995 but not 1996, and machine - picked cotton contains more honeydew- contaminated leaf trash. Except in one instance, thermodetector counts and trehalulose and melezitose content in lint for all sampling methods were significantly correlated.

Lygus susceptibility was found to vary widely from year to year, from region to region and, for some insecticides, even within the season. It is for this reason that producers need current, region-specific recommendations in order to determine which insecticides are most effective at their locale. Our studies were intended to improve understanding of the reliability of glass vial bioassays for estimating efficacy of insecticides used against lygus bugs. Results show that the standard glass vial method offers considerable promise for detecting differences in susceptibility of lygus to some, but not all, insecticides. However, mortality in vial bioassays did not serve as a reliable predictor of the relative toxicity of residues of five insecticides in field treatments. Therefore, field evaluations of insecticide efficacy continue to be essential for selecting the insecticides that provide the best control of lygus. Once the most effective materials are selected from field trial results, bioassays can be used to efficiently monitor changes in population susceptibility to these insecticides. Additional new insights provided by our studies are that efficacy of residues of insecticides declined rapidly, such that after three days all insecticides caused very little mortality to adult lygus bugs. Lastly, we found a marked difference between residual and direct contact toxicity of the five insecticides evaluated. Even the insecticide treatments that resulted in relatively low toxicity in residual exposure tests killed 95-100% of lygus bugs that they contacted directly under field conditions. This finding indicates that producers experiencing severe problems with lygus control would be well advised to improve insecticide coverage.

Experimental insecticides were evaluated for control of lygus bugs relative to commercial standards in cotton. These products were also evaluated for activity towards whiteflies and pink bollworms. CGA293343 was not effective when used as a side-dress material at layby, but was effective toward whiteflies, and towards lygus at higher foliar rates. Regent, Vydate and Mustang + Thiodan were highly effective for lygus control, while EXP61096A and Mustang alone performed poorly. Against whiteflies, CGA293343, Acetamiprid, and Mustang + Thiodan were most efficacious, while Mustang alone and with Thiodan were most effective towards pink bollworms.

Temik 15G (6 lbs/acre) and Thimet 20G (7.5 lbs/acre) granular insecticides were applied in furrow at planting and compared to an untreated check in two experiments in Parker Valley and Mohave Valley, AZ. At first square each of these main plots was split in half and either Temik 15G or DiSyston 8L was sidedressed to each subplot and compared to an untreated strip. Thrips and lygus counts were taken at weekly or biweekly intervals and plant response measured from the 2 or 3 leaf stage through layby. Under the thrips pressure experienced in these two experiments (0.5-1.5/plant), Temik and Thimet at planting provided similar and adequate protection from thrips for up to 7 weeks following application. Temik 15G sidressed at 14 lbs/acre at first square provided lygus bug control for up to 42 days following application under light lygus bug pressure (5-15/100 sweeps). Di- Syston 8L sidedressed at 1 qt/acre at first square provided lygus bug control for 35 days following application under moderate lygus bug pressure (15-20/100 sweeps). Under the conditions of this study, systemic insecticide applications at planting and first square did not increase cotton lint yields of insecticide treated Bt cotton plots, compared to the untreated control plots.

Temik 15G was side-dressed at a rate of 7 lb./acre and 14 lb./acre and compared to an untreated check in 4 experiments in 1996 and 1997 in Buckeye, Az. Treatments were made just prior to early bloom. Lygus counts were taken using a sweep net on weekly intervals for four to six weeks post application. A net positive return on investment (ROI) ranging from $34.79/acre to $48.19/acre was realized in three of the four experiments with the seven lb./acre rate. One experiment resulted in a net economic loss of $24.84. A net positive ROI was experienced in two of the four experiments ranging from $23.31 to $50.11 using the fourteen lb./acre Temik rate. Two of the four experiments resulted in a net loss ranging from $28.28 to $93.27 using the fourteen lb./acre rate. It appears that lint yield increase responses are due in part to a plant response to Temik, not necessarily related to lygus density as evidenced in part by the lack of measured sweep count populations.