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- Author or Editor: K.D. Elsey x
The relative resistance of 18 cultivars of Brassica oleracea L. to attack by the sweetpotato whitefly [Bemisia tabaci (Gennadius)] was studied in screen cage (spring), field (autumn), and laboratory tests. The B. oleracea entries consisted of six types, including 16 green and two red cultivars. Cabbage (Capitata Group) and broccoli (Boytrytis Group) were less infested than other crops in a screen cage test, with kale, collard (Acephala Group), and brussels sprouts (Germmiter Group) experiencing relatively high and kohlrabi (Gongtlodes Group) intermediate infestations. Relative ranking of crops was similar in an autumn field study, with the exception of brussels sprouts, which had an intermediate level of infestation. Differences in numbers of whiteflies among cultivars within crops were negligible or inconsistent, except that red cultivars of brussels sprouts (`Rubine') and cabbage (`Red Acre') were much less infested than green cultivars. In a laboratory test, differences of whitefly oviposition and nymphal survival and development were small, indicating that nonpreference factors, rather than antibiosis, are the best explanations for differences in the numbers of whiteflies among the B. oleracea cultivars that were tested,
Pickle worm [Diaphania nitidalis (Stoll)] and melon worm [Diaphania hyalinata (L.)] moths, released into a screenhouse, laid far more eggs on pubescent than on glabrous plants of cucumber (Cucumis sativus L.). In a field test of the 2 foliage types, a total of 8 times as many melonworm larvae were found on pubescent as glabrous plants, but about the same number of pickle worm larvae were found on both types. Both melonworm and pickleworm moths laid approximately equal numbers of eggs on fiberglass insulation treated with ethanol extracts of the 2 foliage types, suggesting that the presence or absence of pubescence on the leaves determined oviposition preference.