Resistance of a Brassica oleracea germplasm collection (broccoli, Italica Group; cauliflower, Botrytis Group; and collard and kale, Acephala Group) to silverleaf whitefly (SLW; Bemisia argentifolii Bellows and Perring) infestation was evaluated using several measures of insect infestation (including adult vs. nymph counts) taken at plant growth stages ranging from seedling to mature plant. An initial study was conducted in an outdoor screen cage artificially infested with the SLW adults; subsequent field trials relied on natural infestations. The glossy-leaved lines (`Broc3' broccoli, `Green Glaze' collard, and `SC Glaze' collard) had low SLW infestations in cage and field tests. SLW adult counts were less variable than similar comparisons using nymphal counts, although adult and nymph counts were positively and significantly correlated at late plant stages. Based on this study, comparing relative SLW adult populations would be a preferred criterion for identifying B. oleracea resistance to this insect.
Mark W. Farnham and Kent D. Elsey
Steven J. Damon, Russell L. Groves, and Michael J. Havey
replication as random. Plant weight was used as a covariate to account for a possible attraction of onion thrips to larger plants. Results and Discussion Epicuticular wax morphology. SEM micrographs ( Fig. 1 ) revealed no obvious wax crystals on glossy leaves
Sanford Eigenbrode and Jimmy Tipton
Mexican redbud (Cercis canadensis var. mexicana) exhibits resistance to leaf cutter bees (Megachile spp., LCB). Resistant trees (CMG) have glossy leaves and sustain little LCB damage as compared to dull-leaf Mexican redbud (CMD) and the closely related eastern redbud (Cercis canadensis, CC). On average, LCB made 35 times as many cuts per week on CC as on CMG and CMD, even though there were half as many leaves available. Mexican redbud leaves are twice as thick as CC leaves, which may account for LCB preference for the latter. However, leaves from CMG and CMD are similar in leaf thickness, cuticle wax content, and resistance to penetration, yet LCB had an even stronger preference for the former. More than 83 times as many cuts per week were made on CMD over CMG, even though the number of leaves was comparable. CMG leaves have a thicker cuticle on the upper surface that lacks wax crystals present in the CMD and CC. The upper cuticle from CMG leaves also contains fewer lipids and an altered lipid composition (notably fewer long-chain alcohols) compared to CMD.
Wesley E. Kloos, Carol G. George, and Laurie K. Sorge
The cultivated gerbera daisy [Gerbera hybrida (G. jamesonii Bolus ex Adlam × G. viridifolia Schultz-Bip)] often contracts powdery mildew (PM) when grown under conditions of high humidity. During field and greenhouse performance trials conducted with gerberas of the North Carolina State University collection, two half-sib field plants and two of their greenhouse-grown progeny were identified as being highly resistant to PM caused by Podosphaera (Sphaerotheca) fusca (Fr.) Blumer emend. Braun & Takamatsu. These plants were also unusual in having smooth glossy leaves with very low numbers of bristle macrohairs (MHs) on the adaxial leaf surface compared to wild type. The primary objectives of this investigation were to determine the mode of inheritance of PM resistance and MH density traits and determine if there was a causal relationship between the phenotypes. Parental genotypes were determined by testcrosses to wild-type, PM-susceptible and MH-high-density leaf cultivars. For each trait, a series of crosses were made to produce PA, PB, F1, F2, BC1A, and BC1B progeny. Linkage relationships among PM resistance and MH density loci were examined by testcrosses. Phenotypic segregation ratios suggested the presence of a dominant allele, Pmr1, determining PM resistance and an unlinked dominant allele, Mhd, determining low density of adaxial bristle MHs and moderate reduction in abaxial smooth MHs. The Pmr1 allele appeared to be incompletely dominant in some heterozygotes where one parent was from a highly PM susceptible background. Modifying genes may have some affect on the level of PM resistance or susceptibility. The Mhd allele appeared to be incompletely dominant in some heterozygotes. Segregation ratios indicated that the wild-type alleles were recessive to the PM-resistance and MH-low-density alleles and given the designation pmr1 and mhd, respectively. Density of leaf MHs did not affect PM resistance.
, fragrant flowers and large evergreen leaves. This cultivar can be distinguished from other cultivars in Gardenia augusta on the basis of its extremely large (up to 10 cm.) double, fragrant flowers and large evergreen, glossy leaves. It is also quite
Mark W. Farnham
Agriculture in 2008. Each of the released pairs (doubled haploids) includes two uniform and true-breeding broccoli lines that appear identical to one another except that one has normal, nonglossy leaves and the other has glossy leaves. Using the two pairs of
David L. Kidwell-Slak and Margaret R. Pooler
’ (Friends of the JC Raulston Newsletter 13(1):8, 2009): Cercis canadensis var. mexicana with exceptionally glossy leaves and regularly undulate margins. Named by J.C. Raulston but propagation and distribution records uncertain; possibly lost to
Chad E. Finn, Bernadine C. Strik, Theodore A. Mackey, Kim E. Hummer, and Robert R. Martin
, extremely dark green (Green Group N137A), glossy leaves borne on fairly upright shoots. The plant has not shown any susceptibility to foliar diseases such as leaf rust [ Pucciniastrum vaccinii (G. Wint.) Jørst]. Early in the spring, the floral buds break
Chad E. Finn, Bernadine C. Strik, Theodore A. Mackey, Patrick A. Jones, Nahla V. Bassil, and Robert R. Martin
shrubs (0.88 × 0.90 m after 3 years in the field) with attractive, dark green (Green Group 139A), glossy leaves borne on upright shoots. The plant habit is more spreading than that of ‘Perpetua’, and the plant has not shown any susceptibility to foliar
Winston Elibox and Pathmanathan Umaharan
between species of anthurium belonging to the section, Calomystrium, has resulted in an anthurium species complex referred to as Anthurium andraeanum Hort. Anthurium is cultivated primarily for its showy cut flowers and glossy leaves, which are exported