THE EFFECTS OF DRIP OR FURROW IRRIGATION OF COTTON ON BEMISIA-ARGENTIFOLII (HOMOPTERA, ALEYRODIDAE)

Infestations of immatures of Bemisia argentifolii Bellows and Perring (= Bemisia tabaci (Gennadius) Strain B), were studied in surface-drip or furrow-irrigated field plots of short staple cotton, Gossypium hirs utum L., in central Arizona in 1988, 1991, and 1993. Three levels of i rrigation designed to produce low, moderate, or high plant water stres s (at the end of irrigation interval) were tested each year. The seaso nal average numbers of immatures of B. argentifolii on fifth main stem node leaves was greater in biweekly-furrow irrigated than in drip-irr igated plots in 1988 and 1993 but not in 1991. Plants irrigated biweek ly with additional supplemental irrigations during mid-season or full season weekly irrigations had intermediate numbers of immatures. Leaf water potentials (-bars) measured in 1993 indicated plant water stress was greatest prior peak blooming and increased whitefly infestations. The 'Deltapine 50' (DPL-50) cultivar had a similar density of leaf tr ichomes but half as many nymphs per leaf as DPL-77 in the 1991 test. T hese results indicate that selecting a less susceptible cultivar and a voiding plant water stress may be useful in management of whiteflies.