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Gene E. Lester, John L. Jifon, and D. J. Makus

Netted muskmelon [Cucumis melo L. (Reticulatus Group)] fruit quality (ascorbic acid, β-carotene, total free sugars, and soluble solids concentration (SSC)) is directly related to plant potassium (K) concentration during fruit growth and maturation. During reproductive development, soil K fertilization alone is often inadequate due to poor root uptake and competitive uptake inhibition from calcium and magnesium. Foliar applications of glycine-complexed K during muskmelon fruit development has been shown to improve fruit quality, however, the influence of organic-complexed K vs. an inorganic salt form has not been determined. This glasshouse study investigated the effects of two K sources: a glycine-complexed K (potassium metalosate, KM) and potassium chloride (KCl) (both containing 800 mg K/L) with or without a non-ionic surfactant (Silwet L-77) on melon quality. Orange-flesh muskmelon `Cruiser' was grown in a glasshouse and fertilized throughout the study with soil-applied N–P–K fertilizer. Starting at 3 to 5 d after fruit set, and up to 3 to 5 d before fruit maturity at full slip, entire plants were sprayed weekly, including the fruit, with KM or KCl with or without a surfactant. Fruit from plants receiving supplemental foliar K had significantly higher K concentrations in the edible middle mesocarp fruit tissue compared to control untreated fruit. Fruit from treated plants were also firmer, both externally and internally, than those from non-treated control plants. Increased fruit tissue firmness was accompanied by higher tissue pressure potentials of K treated plants vs. control. In general, K treated fruit had significantly higher SSC, total sugars, total ascorbic acid, and β-carotene than control fruit. Fall-grown fruit generally had higher SSC, total sugars, total ascorbic acid and β-carotene concentrations than spring-grown fruit regardless of K treatment. The effects of surfactant were not consistent but in general, addition of a surfactant tended to affect higher SSC and β-carotene concentrations.

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John M. Ruter

Loropetalum chinensevar.rubrum, Chinese fringe-flower, was introduced into the United States in 1989 and quickly became on of the most popular plants in the nursery trade. Growth abnormalities (little-leaf disorder) became a problem on container-grown plants in pine bark substrates during the late 1990s. Symptoms are as follows: darkening of older growth, shortening of internodes, upward cupping of leaves, crinkling of new growth, particularly the distal part of the leaf, decrease in leaf size. In severe cases leaf necrosis occurs along with stem elongation, thus branches appear to be elongating without new leaves. Petioles become very short. Branchlets may also be reflexed or drooping. In Florida, an eriophyid mite has been touted as the causal agent for the disorder. On plants sampled from Georgia nurseries, eriophyid mites have never been detected. `Ruby' consistently has the problem, while it has also been noted on `Sizzling Pink' and `Suzanne'. Plants in the ground do not express the problem. There may be an element present in native soil that is not supplied in sufficient quantity in organic substrates. Foliage from a commercial nursery was sampled for micronutrients concentrations. Initial data indicated that copper, zinc, and nickel were low and could be causing the problem. In May 2005, a study was initiated at a commercial nursery in Grady County, Ga. Copper and zinc sulfate, along with nickel lignonsulfonate, was applied as foliar sprays to symptomatic plants of `Suzanne' growing in #5 containers. Within two weeks after treatment, plants sprayed with copper sulfate resumed normal growth. Control plants, or plants treated with zinc or nickel did not resume normal growth. A second study was initiated in June to evaluate different rates of copper sulfate and Kocide, a copper fungicide. Medium to high rates of copper sulfate and the high label rate of Kocide were effective. The plants in this study had severe symptoms and required repeat applications of copper. Further research is needed on appropriate formulations of copper, rates of application, and rates of incorporation into pine bark substrates to eliminate the problem.

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Wheeler G. Foshee III, Eugene K. Blythe, William D. Goff, Wilson H. Faircloth, and Michael G. Patterson

killed, new growth developed abnormally ( Fig. 1 ). Fig. 1. Abnormal development of new growth on young ‘Sumner’ pecan trees (newly planted, first growing season trees at the initiation of the study) after 12 repeated foliar applications of

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Kuo-Tan Li, Jacqueline K. Burns, and James P. Syvertsen

plants, including citrus ( Alferez et al., 2005 , 2006 ). Using foliar CMNP application, citrus leaves and immature fruit had no visual phytotoxic symptoms and did not abscise when used at a concentration that caused mature fruit abscission. At this CMNP

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Enrique E. Sánchez and Timothy L. Righetti

This study was carried out on mature `Delicious' apple trees (Malus domestica Borkh.) on EM 9 rootstock. Labeled B (99.63 Atom % 10B) was applied as boric acid. Treatments were postharvest foliar B at 375 mg·L–1, postharvest foliar B (375 mg·L–1) plus urea (2.5% wt/vol), and a soil application at the same per-tree rate as the foliar treatments (16 g boric acid/tree). Postharvest foliar B applied with or without urea was efficiently transported from the leaves into storage tissues for the next year's growth. However, soil-applied B remained mostly in the roots while very little was translocated to the above-ground portions of the tree at full bloom. When urea was added to a foliar B spray, the amount of B in the roots and flower clusters increased at full bloom. Although increasing the efficiency of foliar B applications may not be necessary, combining urea and B into a single application is recommended when growers want to apply both N and B. Shoot leaves from all treatments collected late in the season (midsummer) had similar B concentrations, even though treatments altered the amount of added B that was present in different tree tissues early in the season.

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Ren-Huang Wang, Yu-Mei Hsu, Duane P. Bartholomew, Subbiyan Maruthasalam, and Chin-Ho Lin

Foliar application of aviglycine reduces natural flowering in pineapple HortScience 40 123 126 Lin, C.H. Kuan, C.S. Hsu, Y.M. Bartholomew, D.P. 2005 Delaying Natural Flowering in Pineapple 8

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Kellie J. Walters and Roberto G. Lopez

., 1976 ). It is labeled for foliar spray applications on floriculture crops to increase lateral branching, abort flowers and flower buds, and inhibit internode elongation ( Currey et al., 2016b ; Hayashi et al., 2001 ); although not labeled, recent

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Shanshan Sun, Mengying An, Liebao Han, and Shuxia Yin

osmotic adjustment. In accordance with the results of Athar et al. (2008) , treatments with NaCl resulted in a marked increase in MDA and H 2 O 2 contents. However, foliar application of EBR effectively reduced MDA and H 2 O 2 content, and particularly

Open access

Y. Erner, S. Schwartz, A. Bar-Akiva, and Y. Kaplan

Abstract

Band application of MgCl2·6H2O under the tree canopy of ‘Shamouti’ orange [Citrus sinensis (L.) Osbeck] trees significantly increased leaf Mg and Cl concentration. MgSO4 and MgO were not effective. Fertigation with MgCl2·6H2O was less efficient than band application and was not superior to foliar application of Mg(NO3)2·6H2O for increasing leaf Mg concentrations. In spite of high Cl concentration of the leaves, no visible toxicity symptoms were observed.

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D.K. Harris, A.D. Owings, and S.E. Newman

Poinsettias and other floral crops when treated with the growth retardant uniconazole, Sumagic™, are more compact in growth habit. They have also been shown to have reduced stem strength. Calcium applied as a drench has been demonstrated to increase plant height and plant dry weight of poinsettias. Unicomazole reduced plant height without affecting dry weight. Bract color was more intense when calcium was applied as a weekly spray. Poinsettia plants had greater levels of foliar calcium when applied as a drench. Poinsettia plants sprayed and drenched with calcium and treated with uniconazole had greater levels of foliar calcium, however, this was not significantly greater than the control plants treated with uniconazole alone. The lowest level of foliar calcium was observed in uniconazole treated plants where calcium was applied as a spray. Uniconazole applications weakened the stein structure of poinsettias as with other floral crop species.