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.

The susceptibility of cotton to spring emergence of pink bollworm (PBW) was evaluated for a variety of planting dates in Pinal Maricopa, LaPaz and Yuma counties using historical climate records and heat-unit-based models that predict PBW emergence and cotton development. Early planted cotton proved most susceptible to the PBW emergence, however, cotton type (shoe vs. long staple) and springtime weather conditions both played an important role in overall susceptibility.

Field experiments conducted in 1989 comparing effects of planting date and irrigation termination date on pink bollworm in both in- season and overwintering infestations indicated different responses depending upon the location and type of cotton. Tests were located at: Yuma Agricultural Center; Marana Agricultural Center; and Maricopa Agricultural Center. Infestations at Yuma ranged from 0% at early flowering to 80% infested bolls prior to harvest. Marana had equally high infestations at the end of the season, while Maricopa had the lowest infestations ranging from 2% to 5% for Pima and 3 %-17% for Upland. Planting date or species of cotton did not affect early infestation. Data comparing plots for overwintering infestations are still being evaluated. Continuous insecticide treatments were made at all locations after squaring began.

Cotton cultivars and germ plasm lines were screened for resistance to pink bollworm. Sixteen advanced strains were selected for resistance to pink bollworm and/or high yield potential. In a regional early maturing germ plasm lines test, only the short- season check had less seed damage caused by pink bollworm than did the long-season check. Five lines yielded more lint than both checks. In a Pima test, Pima S-6 nectariless had 14% less seed damage than Pima S-6. Seven pink-bollworm-resistant germ plasm lines will be released in the near future.

Ethephon applied at rates of 0.50 or 0.75 lb AI/acre removed early-season squares and delayed initiation of pink bollworm, Pectinophora gossvpiella (Saunders) infestations and reduced the number of infested bolls on early-season fruiting branches, without affecting yield except for ethephon at 0.751b AI /acre at one location. Higher rates of application reduced yields. In most cases, ethephon treatments delayed flowering but plants compensated for removal of early- season squares and equalled or surpassed accumulated flowering of untreated control plants later in the season.

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