The Western Growers Association and Arizona Cotton Growers Association worked cooperatively with a group of University of Arizona scientists, Arizona Department of Agriculture officials and regional pest control advisors to develop general guidelines for managing whiteflies and specific recommendations for Applaud and Admire use. This was achieved by identifying differences in crop production, insecticide use, and whitefly population dynamics on key host crops within three distinct growing regions in Arizona. Data was compiled that when graphically illustrated identified important, multidimensional interactions within cropping systems. Based on the patterns resulting from our analysis, initial recommendations have been formulated to harmonize chemical use across commodities by restricting Applaud use to only once per crop season in use windows, with additional guidelines for reducing the possibility of exposing successive whitefly generations to the same mode of action. The diversification and limitation of Admire and other active ingredients, and the employment of cultural practices are also be considered. Should this model of cooperation be successful, valuable and scarce modes of action may also be shared in the future within diverse, integrated use systems.

Whitefly populations in the Yuma area have been reduced to levels that growers can cost-effectively manage. Data from our studies suggest that these declines in pest populations are largely attributed to the use of Admire 2F (imidacloprid) soil treatments. Relative to the outbreaks in 1993-1994, whitefly populations during the past four growing seasons have remained at sub-economic levels on lettuce crops throughout the growing areas in Yuma This chemical has provided excellent control of whiteflies on fall lettuce, and aphids on spring lettuce. After 6 years of evaluation in commercial fields, the product appears to remain highly efficacious, maintaining good residual activity. Studies in 1998 on fall broccoli and melons crops further support this conclusion. Factors responsible for this sustained efficacy of Admire are discussed.

Spinosad (Success7), chlorfenapyr (Alert7), DPX-MP062 (DuPont), thiodicarb (Larvin7), and cryolite (Kryocide7) progressively reduced the total number of Plutella xylostella (diamondback moth, DBM) following each of three applications. Success treated cabbage had the fewest number of small-sized DBM larvae after the first application and maintained very low numbers following subsequent applications. Relative performance of the insecticides based on efficacy indicated by a seasonal average of total DBM larvae showed that Success was highly effective followed by methomyl (Lannate) and Larvin. Emamectin-benzoate (Proclaim7), Alert, and DPX-MP062 performed comparably and tebufenozide (Confirm7) and Kryocide were less effective.

Cantaloupe leaf damage from leafminer activity was minimal to non-existent when evaluated at 6 days after treatment (DAT) following each of the first four weekly application dates. At 13 DAT-4, the number of mined leaves increased tremendously over the previous observation date. The untreated cantaloupes showed an increase from 30.8 to 81.8 mined leaves compared to the previous week. Agri-mek and the alternation treatment of Trigard, Success7, and Agri-mek applied on cantaloupes showed the fewest number of mined leaves at about 22 mined leaves. Trigard and Success treated cantaloupes had increased number of mined leaves ranging from 44 to 56.8. Agri-mek and the alternation treatment consistently had the fewest number of mined leaves during the course of the test period. Trigard and Success treatments performed similarly and reduced the number of mined leaves relative to the untreated cantaloupes. Success at the higher rate appeared to be slightly more active by showing numerically fewer mined leaves than the lower rate of application. Success treated melons yielded nearly twice as much compared to the other treatments and the untreated. Success treated melons also offered a higher number of marketable fruit at better than 80% compared to about 60% for the other treatments. Less stickiness was observed on the Success treated cantaloupes. There appeared to be an effect from Success applications on whitefly to reduce the honeydew stickiness.

A new insect management technology known as "particle film" technology (Surround) was evaluated for it potential for control early fall pests of head lettuce in Yuma, AZ. Surround did appear to slightly reduce larval population of cabbage looper, beet armyworm and Heliothis, but not enough to be considered a commercially effective treatment. Additionally, Surround appeared to antagonize Success’s activity towards cabbage loopers. Against whiteflies, Surround did appear to reduce ovipositioning, but resultant impact on the nymph population could not be adequately assessed. Overall, Surround does not appear to have good fit in the pest management system in leafy vegetables in Yuma, AZ.

An insect pest monitoring network spanning the major growing areas in Yuma was implemented in 1998-1999. This project was designed to measure the relative activity and movement of adult populations during the growing season and provide important information to growers and PCA’s. A series of pheromonebaited and yellow sticky traps were placed in 11 locations among the growing areas in the Yuma, Gila and Dome Valleys in Yuma county. Numbers of adults / trap /night were recorded weekly from September-April. Seasonal differences in insect species activity and abundance among locations were observed, but difficult to precisely explain because of the lack of historical trap data. Information gathered from the trapping network will provide historical baseline data for pest activity on an area wide basis from which relationships between insect trap captures and seasonal factors that influence their activity and abundance may be explained. The results of the monitoring network during the 1998-1999 growing season for is provided in this report.

Subsurface drip irrigated broccoli received experimental combinations of N rate (176 and 268 lb N/ac, and fertigation frequency (daily, weekly, bi-weekly, monthly) at the Maricopa Agricultural Center during winter 1998-99. Marketable broccoli yields were increased slightly with N applications of 268 lb/acre compared to 176 lb/acre. However, neither marketable yield, head diameter, nor petiole nitrate concentrations were significantly affected by fertigation frequency. Nitrogen fertigation frequency does not seem to be a critical management variable for subsurface drip irrigated broccoli grown on medium-textured soils in Arizona.

Twelve green bean varieties were grown in a replicated small plot trial on the Safford Agricultural Center in 1998. Varieties were picked regularly during the growing season. Yields are shown in tabular form and also graphically to indicate how each variety performed throughout the season. Rapids produced the highest yield with a total over 1.3 tons per acre. Two other varieties, Shade and HMX 6999, also performed well with yields over 1.0 tons per acre.

Eight varieties of bell peppers, three varieties of long green chile, two varieties of jalapeños, two varieties of yellow wax and one Serrano pepper were grown in a replicated small plot trial on the Safford Agricultural Center in 1998. Varieties were picked regularly during the growing season.

Four slicing and two Roma-type tomato varieties were grown in a replicated small plot trial on the Safford Agricultural Center in 1998. Varieties were picked regularly during the growing season with total tonnage picked being tabulated and plot weights by variety shown graphically against time during the season. Balboa variety of slicing tomato and Toro variety of Roma-type tomato were the highest yielding varieties with yields of 69 and 76 tons per acre respectively.