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Title: SWEETPOTATO WHITEFLY COLONIZATION ON SMOOTH OKRA-LEAF CULTIVARS REDUCED ON UPLAND COTTONS

Author
item CHU, CHANG CHI
item NATWICK, ERIC - UC COOP HOLTVILLE
item FITZGERALD, GLENN
item CHEN, TIAN-YE - U OF AZ MARICOPA
item HENNEBERRY, THOMAS

Submitted to: European Whitefly Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/5/2004
Publication Date: 10/5/2004
Citation: Chu, C., Natwick, E.T., Fitzgerald, G.J., Chen, T., Henneberry, T.J. 2004. Sweetpotato whitefly colonization on smooth okra-leaf cultivars reduced on upland cottons. European Whitefly Symposium Proceedings, p 64.

Interpretive Summary: We have studied the relationship between leaf morphology and whitefly colonization since 1996. Results showed that smooth okra-leaf upland cottons had fewer whiteflies compared with normal-leaf cottons. Analysis showed that the smooth okra-leaf character reduced whitefly adult density by 38% and nymphs by 30-32% comparing with hariy normal-leaf cottons. The reduction was primarily due to fewer trichomes underleaf followed by leaf shape.

Technical Abstract: The development of resistant cottons Gosspium spp., has potential for reducing colonization of sweetpotato whitefly (SPW), Bemisia tabaci (Gennadius) biotype B, in the field. Studies have been conducted since 1996 to define the relationships between SPW population density and leaf morphology of upland cotton. Results showed that smooth okra-leaf cottons reduced SPW adults and immatures by 38% and 30-32%, respectively compared with hairy normal-leaf cottons. Multiple regression analyses suggested that underleaf trichome and leaf perimeter-leaf area ratio accounted for 53.2% and 12.9% for the variation in numbers of adults per leaf, respectively, and trichome and leaf perimeter accounted for 62.2% and 5.8% for the variation in numbers of immatures per cm2 leaf disk. When both factors were considered, the equations accounted for 66.1 and 68.0% of the variation in number of the adults per leaf and immatures per cm2 of leaf disk, respectively. Results in 2002 studies show progressive increases in SPW damage to hairy normal-leaf and smooth okra-leaf cottons that were identifiable in infrared photos taken during the season.