Submitted to: National Research and Action Plan for Silver Leaf Whitefly
Publication Type: Abstract Only
Publication Acceptance Date: 2/14/1997
Publication Date: N/A
Technical Abstract: Fourteen collard entries, Brassica oleraceae L. Acephala group, were evaluated for resistance to whiteflies (primarily Bemisia argentifolii) at Charleston, SC, 1993-95. Three glossy types, Green Glaze-Glossy, SC Glaze, and P. Smith, averaged 20, 27, and 35 adults/plants, respectively, compared to 400+ adults/plant on Morris Heading. They averaged 0.1 nymph/cm2, compared to 2.5 nymphs/cm2 for the susceptible genotypes. These genotypes have reduced leaf waxes, which causes their glossy or shiny appearance. Green glaze segregated for a glossy (resistant) and a nonglossy (susceptible) type. Two normal-appearing F1 hybrids (Blue Max and Top Bunch) had significantly fewer whitefly adults, nymphs, and eggs than the open-pollinated, susceptible cultivars. However, they were not as resistant as the glossy collards, and the mechanism of resistance is unknown. Rankings for whitefly resistance were consistent from year to year, and there were significant correlations between counts of adults and counts of eggs + nymphs. For 1995, there were approximately equal numbers of whitefly eggs on leaf positions 4 and 10. Most nymphs were counted on leaf position 10; and there were few numphs on leaf position 4, probably because the eggs on these leaves had not yet hatched. Results from a late 1995 field experiment were consistent with results from 3 years of spring plantings.