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  • Author or Editor: Gordon E. Holcomb x
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Abstract

Euphorbia pulcherrima Willd. is a popular Christmas flowering pot plant that occasionally is used as a cut flower. Popularity of the poinsettia cut flower is limited by its short postharvest life. When the poinsettia is cut, a milky latex excreted from the cut stem accumulates and prevents uptake of water, resulting in rapid wilting of the leaves and bracts (2). Several methods of preventing latex flow have been proposed, including heat searing, dipping in boiling water, and dipping in alcohol (2, 3). Freyermuth et al. (1) showed that treating the cut stems with al cohol was the best method for improvement of the postharvest quality of cut poinsettias. The objective of this study was to determine when the alcohol pretreatment could be applied, and whether a flower preservative had any effect on postharvest life of cut poinsettia.

Open Access

Dimethyl ammonium chloride (DAC, `Triathlon'), sodium hypochlorite, formaldehyde, and streptomycin (`Agri-mycin 17') were used as dips to treat Zantedeschia rehmannii superba Engl., Zantedeschia elliotiana ×maculata (Hook.) Engl., and Zantedeschia albomaculata (W.Wats.) Baill. rhizomes to control Erwinia soft rot. A 30 min 200 ppm (mg·L−1) streptomycin dip provided the best control of Erwinia soft rot for all three Zantedeschia species and a 1-hour 10% formaldehyde dip provided the second best control of inoculated rhizomes. Rhizomes inoculated with Erwinia required more days to emerge. Chemical treatments did not affect days to emergence or final plant growth.

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Performance evaluations of numerous annual and perennial herbaceous ornamentals were conducted in landscape settings in 2004 at the LSU AgCenter in Baton Rouge. A mid-summer through fall evaluation of Kong coleus found no difference in flowering performance and visual quality ratings of the five available cultivars. In a sun/shade study, Kong coleus cultivars in 60% shade were about 50% shorter than those in sun. Other impressive coleus have been Aurora Black Cherry and Mississippi Summer Sun. The Stained Glassworks series of coleus have been average performers. The Son series of lantanas (Sonrise, Sonset, Samson, Sonshine) have been top performers in terms of visual quality and continual bloom. All-America daylilies most prevalent to rust symptoms have included Judith, Leebea Orange Crush, Starstruck, Lady Lucille, and Chorus Line. Some rust has also been noted on Plum Perfect and Frankly Scarlet. Profusion Apricot and Profusion White have been less susceptible to Xanthomonas bacterial petal blight than Profusion Fire, Profusion Cherry, and Profusion Orange. Earth Kind roses, being promoted by Texas A&M, are being evaluated for landscape performance along with black spot and powdery mildew susceptibility. Most problematic cultivars thus far have included Georgetown Tea, Clotilde Soupert, Nacogdoches, Reve d'Or, New Dawn, Souvenir de St. Anne's, Spice, Lamarque, Puerto Rico, Sarah Jones, Ducher, and Louis Philippe. Lady Bird cosmos have been good late summer/early fall landscape performers.

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All-American daylily cultivars named from 1994-2004 were evaluated for landscape performance and daylily rust (Puccinia hemerocallidis) susceptibility during 2003 and 2004. Cultivars included `Black-Eyed Stella', `Bitsy', `Leebea Orange Crush', `Plum Perfect', `Judith', `Starstruck', `Frankly Scarlet', `Lullaby Baby', `Lady Lucille', and `Chorus Line'. Bareroot plants were planted in raised beds composed of an Olivier silt loam soil in full sun and received irrigation as needed to prevent stress. Visual quality ratings were made weekly from 19 Apr. to 25 Oct. 2003 and 15 Mar. to 20 Sept. 2004. Included in the visual quality ratings were growth habit and flowering with favorable growth habit being compactness, foliage color, uniformity, and overall aesthetics, and favorable flowering being longevity and visual appeal. Flower observations were made in regard to time in bud and peak blooming periods over the same time frames. Daylily rust ratings were taken in September and November 2003 and in August and November 2004. Flowering observations indicated that Black Eyed Stella and Bitsy were the only cultivars showing reliable repeat bloom potential. Among the other cultivars, Judith was the earliest to bud and bloom but also had a blooming period of only 2 to 3 weeks compared to 4 to 5 weeks of bloom for other cultivars. Rust was most prevalent on Judith, Leebea Orange Crush, Starstruck and Lady Lucille. Judith and Leebea Orange Crush have rust symptoms earlier than other cultivars. `Plum Perfect', `Frankly Scarlet', `Bitsy', `Black Eyed Stella', and `Lullaby Baby' were least susceptible to daylily rust.

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