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  • Author or Editor: T. W. Whitaker x
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Abstract

Cripshead (iceberg) lettuce accounts for the major portion of commercially produced lettuce in the U. S. Crisphead types are not, however, commonly grown by home gardeners because of misunderstandings about cultural practices necessary to ensure head formation. Two important factors are planting date and thinning of seedlings. Lettuce should be planted when temperatures are favorable: 17-28°C day and 3-12°C night (2). Warmer temperatures will cause bushiness, bolting, and tipbum. Cooler temperatures will delay head formation and reduce head size. Lettuce should be thinned at the 2-3 leaf stage to increase postthinning survival and ensure even maturity; plants should be spaced 25-35 cm apart (2). If the home gardener is successful in producing a well-formed head, it is often too large to be consumed in a single meal, and if stored in the refrigerator, it loses its ‘fresh-picked’ quality and appeal. Leaf and cos types of lettuce are more popular with home gardeners because they do not form heads and individual plants produce high-quality leaves over a long period of time. An objective of this program was to produce a highquality iceberg lettuce with smaller sized heads for home gardeners.

Open Access

Abstract

Cos (romaine) lettuce (Lactuca sativa L.) accounted for less than 5% of California lettuce production in 19783. Cos lettuce adds color, flavor, and texture to tossed (chopped) lettuce salads. In addition, cos lettuce is more nutritious than crisphead lettuce (1).

Open Access

Abstract

Nomenclature rules are proposed for naming genes of species in the Cucurbitaceae. Genes of cucumber, muskmelon, watermelon, squash, and other cucurbits are reviewed and, when necessary, changes in gene symbols are proposed. The number of known qualitative factors include 68 genes for the cucumber, 37 for muskmelon, 25 for watermelon, and 30 for Cucurbita species.

Open Access

Abstract

When given a choice, the cabbage looper, Trichoplusia ni (Hübner), preferred lettuce for oviposition over chard [Beta vulgaris L. (Cicla group)], cabbage [Brassica oleracea (Capitata group)], broccoli (Brassica oleracea L. [Italica group)], and spinach (Spinacia oleracea L.). Preference did not appear to be related to leaf area or to any factor that enhances the survival of progeny of a particular plant species. A 20- to 29-fold difference in oviposition was noted on lettuce grown under 2 environmental conditions.

Open Access

Abstract

In the paper, Studies of Ovlpositional Preference of Cabbage Looper on Progenies from a Cross between Cultivated Lettuce and Prickly Lettuce by A. N. Kishaba, J. D. McCreight, D. L. Coudriet, T. W. Whitaker, and G. R. Pesho (J. Amer. Soc. Hort. Sci. 105(6):890–892. 1980), the last sentence of the first paragraph should read: Two of the plant introductions, PI261653 (Lactuca saiigna) and PI274372 (L. serriola) were less preferred as oviposition sites (7). In addition, reference 2 of the literature cited should be deleted and references 3 through 12 should be renumbered 2 to 11 to accurately correspond with citations in the text.

Open Access

Abstract

F1 progenies from a cross between Lactuca sativa L. breeding line 54671 and L. serriola L. PI 274372 (resistant to the cabbage looper, Trichoplusia ni (Hubner), averaged 42 ± 6 looper eggs per plant, compared to 213 ± 25 for the 54671 parent and 17 ± 4 for PI 274372. Two F2 populations varied widely in plant damage inflicted by the resulting larvae when they were exposed to 4 releases of adult loopers but the damage distribution was skewed towards the resistant parent. Antixenosis of 16 F3 progenies was independent of plant size (r ranged from 0.02 to 0.52) and of plant type (r ranged from 0.00 to 0.57).

Open Access