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- Author or Editor: Henry M. Donselman x
Tissue culture labs based in countries with high labor costs are becoming more dependent on proprietary plants. This has increased the necessity of high profile plant breeding programs. Foliage and flowering plant breeding programs have evolved rapidly to take advantage of the benefits associated with tissue culture labs.
Breeding strategies and methods will be discussed on existing flowering and foliage programs for Anthuriums, Euphorbia, Aloe, Spathiphyllum, Homalomena, and Dieffenbachia. Embryo rescue in the lab has increased the survival of wide crosses from different species within a genera. Rapid multiplication of selected clones has increased the efficiency of screening for disease and insect resistance in the selection of new cultivars. Marketing, along with improved horticultural characteristics, determine the success of new releases.
Abstract
West Indian mahogany [Swietenia mahagoni (L.) Jacq.] grown outdoors under 63% shade in southern Florida exhibited 3 distinct growth phases during the autumn and winter months. During the first phase (September through November), long-day conditions enhanced growth beyond that of natural daylength plants. In the 2nd phase (December through February), plants were essentially quiescent under both photoperiodic regimes in response to cool temperatures. In the 3rd phase (beginning in March), both long-day and natural daylength plants resumed growth at comparable rates. Thus, extending the photoperiod increases the growth rate in the autumn, but has little effect thereafter.
Abstract
Extractability (in 1 n NH4OAc, pH 7.0) of Mg, Fe, Mn, Zn, and Cu from a Canadian peat, perlite, and sand medium amended with 6 commercial micronutrient fertilizer mixes was determined over an 80-week period with semi-weekly leaching. With the exception of Fe from FeDTPA, which dropped rapidly from very high levels to almost zero, and Fe from Esmigran, which was not extractable by NH4OAc, levels of all 5 elements from most fertilizer sources decreased slightly during the 1st month but then remained rather constant for the remainder of the 18 month experimental period. Extractable Mn, Zn, and Fe were reduced significantly by the superphosphate in Micromax Plus.
Abstract
The oleander aphid, Aphis nerii Fonscolombe, is a common pest of oleander, Nerium oleander L. Acephate, bendiocarb, chlorpyrifos, dimethoate, fenvalerate, methidathion, methomyl, permethrin, phosalone, and pirimicarb provided 100% control for 5 days after one spray application. Dimethoate, fenvalerate, methomyl, and pirimicarb provided additional residual control when plants were reinfested with aphids 5 days posttreatment.
Abstract
A leafspot disorder of Ficus elastica Roxb. ‘Robusta’, previously reported as being caused by K deficiency, was induced experimentally by withholding water or growing plants in full sunlight. Leafspots formed on lower surfaces of recently matured leaves of containerized plants grown under the above conditions. Leafspotting was worse on sun-grown plants that were water stressed, air layered, or both. Leafspots were not observed on shade-grown plants which were not subjected to water stress. Leaf diffusive resistance was highly correlated with leafspot incidence, indicating that the most severely stressed leaves also had the most spots. In severely stressed plants, air layering increased the time required for stomatal reopening following irrigation from 24 to 48 hours, prolonging the water stress of leaves above the girdle. Air layering by girdling resulted in significantly more spotting on field-grown plants than air layering by vertically slitting the stem. Root development of air layers was comparable using either method of air layering.
Abstract
Fifty-two cultivars of cannas (Canna X generalis L.H. Bailey and C. indica L.) were evaluated in a field planting for relative susceptibility to Hippeastrum mosaic (HM), a disease caused by Hippeastrum mosaic virus. The cultivars ‘Mrs. Pierre S. DuPont’ and ‘Pink Gem’ were the most susceptible to HM, while 2 red-leaved cultivars, ‘Wyoming’ and ‘Ambassador’, were highly resistant. Thirty-eight cultivars of cannas grown in containers were evaluated for susceptibility to canna rust (Puccinia thaliae Dietel). The cultivars ‘Halloween’ and ‘Yellow King Humbert’ were highly susceptible to rust, while the most resistant cultivars, ‘Louis Cayeaux’ and ‘La Boheme’, were still moderately susceptible. No single cultivar exhibited good resistance to both HM and rust.
Abstract
The genus Heliconia (Heliconiaceae) includes a number of species showing potential as commercial cut flower crops (1). H. Psittacorum and some of its hybrids (e.g., ‘Golden Torch’) are particularly promising because of their attractive flowers, long straight clean peduncles, prolific year round flower production, excellent postharvest characteristics, and few pest problems. The inflorescences can be used in a manner similar to those of bird-of-paradise (Strelitzia reginae), but they are less massive and are therefore, easily incorporated into smaller floral arrangements.