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ARS Home » Research » Publications at this Location » Publication #76636
Title: SUPPRESSION OF BEMISIA TABACI (HOMOPTERA: ALEYRODIDAE) INFESTATIONS IN CANTALOUPE AND COTTON WITH SPRINKLER IRRIGATION

Author
item Castle, Steven
item Henneberry, Thomas
item TOSCANO, NICK - UNIV OF CA, RIVERSIDE

Submitted to: Crop Protection
Publication Type: Abstract Only
Publication Acceptance Date: 1/1/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Immediate declines in local sweetpotato whitefly (SPW) populations were noted in cotton and melon crops following brief, but intense rainfalls. Extended periods of rainfall have been implicated in overall reduction of regional populations. We conducted field studies in Imperial Valley, CA over 2 years to examine if sprinkler irrigation would also reduce SPW populations in cantaloupes and cotton. Results demonstrated significant reductions of whitefly infestations in sprinkler irrigated compared to furrow irrigated plots. Melon fruit yields were significantly greater in daily sprinkler plots compared to biweekly sprinkler plots, and no fruit was harvested in furrow irrigation plots due to intense SPW infestations. In 1993 results in both cotton and cantaloupe were similar. Numbers of whiteflies were lower through summer in cotton, yields were lower than in furrow irrigated cotton, suggesting the need to curb excess vegetative growth. A potential limitation to sprinkler use is higher costs compared t furrow irrigation. These might be partially offset if reduced SLW infestations resulted in less insecticide use. Further cost reduction would be possible if chemigation were incorporated, eliminating costs of ground or air applications. Similar to beneficial effects of timely rainfall, sprinkler irrigation in cotton could help to eliminate price discounts imposed by cotton ginners due to honeydew contaminated lint associated with whitefly infestations.

Technical Abstract: A series of field experiments were conducted to evaluate Bemisia tabaci (Genn.) infestations in both sprinkler and furrow irrigated cantaloupe and cotton plots under conditions of intense whitefly pressure in Imperial Valley, CA. Various fungal pathogen and insecticide treatments also were compared within each irrigation regime. A consistent finding throughout all experiments was that densities of immature whiteflies were significantly reduced in sprinkler irrigated plots. This was most evident in sprinkler irrigated cantaloupe plots treated with the insecticide imidacloprid, as plants survived whitefly infestations to produce marketable fruit in these plots only. Similarly, whitefly densities in imidacloprid-treated/sprinkler-irrigated cotton were significantly lower than all other treatments. Spray applications of insect fungal pathogens were for the most part indistinguishable from the untreated control in terms of densities of whiteflies. Results from the first cantaloupe trial indicate that sprinkler irrigation on a daily schedule resulted in consistently lower whitefly infestations compared to a biweekly schedule.