Boll weevil (Anthonomus grandis Boheman) infestations have been increasing in the large cotton growing area around Phoenix, Arizona since 1978 but became increasingly damaging in the Laveen area in 1985. Heavy rainfall in some fall seasons has caused numerous plowup violations because irrigation termination and harvest took place too late. Late August irrigation at four Laveen locations in 1986 produced as much Deltapine 90 lint as early September irrigation. In 1987 late August irrigation developed as much Upland (Gossypium hirsutum L.) lint per acre as September irrigation. In 1988 September 8 irrigation of lateplanted Deltapine 77 required September irrigation for higher yield. These results indicate that newer varieties may be terminated as early or earlier than older varieties to facilitate crop termination and earlier plowup.