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.

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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.

Studies were conducted in Phoenix AZ, to determine the development of boll weevil, Anthonomus grandis Boheman, infestations in late - season cotton bolls, the pattern of boll weevil emergence, and survival /mortality in the bolls. Boll weevils emerged from bolls buried in moist vermiculite over a period of 232 to 239 days, from 29 January to 2 August. Higher percentages of emergence and lowest mortality in bolls occurred in bolls collected in November as compared to bolls collected in December. Few boll weevils emerged from bolls held under dry conditions in an outdoor insectary for 174 days. However, an average of 16% of the weevils were found alive in the dry bolls in late May.

An experimental cotton line, WC-12NL (nectariless, okra leaf early maturing) was compared in large plot (2-acre) replicated experiments with a standard cultivar, 'Deltapine 61' ( nectaried, regular leaf shape, full-season), for 3 seasons, 1986 to 1984 at 2 locations, Maricopa, AZ and Brawley, CA. Ethephon ("Prep") was applied to half of each plot when the crop was ca. 60% open. Pink bollworm (PBW) eggs were counted twice weekly on bolls and the 2 cottons were sprayed separately for PBW control when the egg infestation on bolls reached the action level. Seed cotton was harvested weekly as soon as bolls started to open. Over the 3 seasons and 2 locations, WC 12NL yielded 12% more total lint, 43% more cumulative lint at the third harvest date, and required only 59% as much insecticide to control PBW as did Deltapine 61.

In 1988 severe beet armywonn (BAW) infestations resulted in damaged cotton flowers and foliage. Some insecticide applications failed to eliminate larvae in the flowers because applications were applied before the flowers opened. Applications made after flowers were open were more effective. In 1989, tests were conducted to define further these results. Karate™ applied when cotton flowers were open achieved 90% control compared to 9% when flowers were closed in one test, and 97% compared to 13 %, respectively, in a second test (P\0.01). A higher percentage (18 %) of cotton bolls was shed on day 7 following flower infestations than were shed (6 %) when flowers were not infested.

Gossyplure, the pink bollworm, Pectinophora gossvpiella (Saunders), sex pheromone is an excellent tool as a bait in traps for detection, survey, research and monitoring male moth populations. We studied the within - and between-seasonal changes of pink bollworm male moth catches in gossyplure-baited live traps installed in cotton fields each year from 1981 to 1988. Seasonal average number of male moths caught varied from 14/trap/night in 1982 to 148 /trap /night in 1981. Male moths caught/trap/night were highly correlated with the minimum air temperatures. The number of male moths caught from March to June were significantly correlated with those caught from July to August, indicating that early spring trapping can be used to identify potential problem fields.

Studies were conducted to identify potential sources of cotton germ plasm resistant to sweetpotato whitefly (SPW), Bemisia tabaci (Gennadius). Numbers of adult SPW sampled using black pan and vacuum methods showed reduced numbers of SPW on GC-EXP-7007 experimental variety vs. all other entries. However, numbers of SPW pupae on leaf samples in most cases were not different. Pima P-62 had the high numbers of SPW adults per blackpan sample, and highest number of pupae/leaf sample.