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Christian A. Wyenandt, Lisa R. Maimone, Kathryn Homa, Angela M. Madeiras, Robert L. Wick, and James E. Simon

detected on or in seed of cultivars for which no symptoms (i.e., no chlorosis or sporulation) were present, indicating that P. belbahrii may infest or reside in or on seed of Ocimum species or cultivars that are otherwise considered resistant to the

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Maurus V. Brown, James N. Moore, and Patrick Fenn

Plasmopara viticola infects and sporulates through stomata of susceptible grape leaves. Sporulation, chlorosis, and necrosis ratings were made in 1994 and 1995 on grape selections and cultivars and Vitis species grown in a fungicide-free vineyard. Cellulose-acetate impressions were made of the abaxial leaf surfaces and stomata were carefully counted within a circle 100 μm in diameter under a light microscope. Leaves were rated as either pubescent or glabrous. There were significant differences among genotypes for sporulation, chlorosis, and necrosis for 1994 and 1995, with highly significant correlations over both years. Stomatal densities were significantly different, but there were no correlations among levels of downy mildew and stomata! densities. Pubescent leaves had significantly higher sporulation, chlorosis, and necrosis ratings for downy mildew than glabrous leaves over both years.

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Anil P. Ranwala and William B. Miller

Experiments were conducted to evaluate storage temperature, storage irradiance and prestorage foliar sprays of gibberellin, cytokinin or both on postharvest quality of Oriental hybrid lilies (Lilium sp. `Stargazer'). Cold storage of puffy bud stage plants at 4, 7, or 10 °C in dark for 2 weeks induced leaf chlorosis within 4 days in a simulated consumer environment, and resulted in 60% leaf chlorosis and 40% leaf abscission by 20 days. Cold storage also reduced the duration to flower bud opening (days from the end of cold storage till the last flower bud opened), inflorescence and flower longevity, and increased flower bud abortion. Storage at 1 °C resulted in severe leaf injury and 100% bud abortion. Providing light up to 40 μmol·m-2·s-1 during cold storage at 4 °C significantly delayed leaf chlorosis and abscission and increased the duration of flower bud opening, inflorescence and flower longevity, and reduced bud abortion. Application of hormone sprays before cold storage affected leaf and flower quality. ProVide (100 mg·L-1 GA4+7) and Promalin (100 mg·L-1 each GA4+7 and benzyladenine (BA)) effectively prevented leaf chlorosis and abscission at 4 °C while ProGibb (100 mg·L-1 GA3) and ABG-3062 (100 mg·L-1 BA) did not. Accel (10 mg·L-1 GA4+7 and 100 mg·L-1 BA) showed intermediate effects on leaf chlorosis. Flower longevity was increased and bud abortion was prevented by all hormone formulations except ProGibb. The combination of light (40 μmol·m-2·s-1) and Promalin (100 mg·L-1 each GA4+7 and BA) completely prevented cold storage induced leaf chlorosis and abscission.

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J.M. Spiers and J.H. Braswell

The effects of varying Al, Mn, and Ca fertilization levels on `Tifblue' and `Brightwell' rabbiteye blueberry (Vaccinium ashei Reade) plant growth, chlorosis symptoms, and leaf elemental content were studied in a sand culture experiment. Increased Al fertilization linearly decreased Ca, Mg, and Mn leaf concentrations and plant vigor. Calcium fertilization did not affect plant growth or leaf concentration of the two cultivars. Increased Mn fertilization increased Al and Mn leaf concentrations and resulted in more chlorosis symptoms. Plants fertilized with the highest rates of Al and Mn had the least amount of growth.

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C. A. Conover and H. M. Vines

Abstract

Chlormequat (Cycocel, CCC) sprays and drench reduced plant height of poinsettias. Sprays of 5000 ppm were most effective with 25% reduction after 32 days followed by 3000 ppm - 18%, 1000 ppm - 17%, and 5000 ppm drench 12%. Appearance as indicated by chlorophyll analyses and chlorosis ratings was most seriously affected by sprays of 5000 ppm followed by 3000 ppm. The spray application of 1000 ppm and drench of 5000 ppm showed no deleterious effect to appearance. High fertilizer rates stimulated chlorophyll regeneration following spray applications of chlormequat partially overcoming the induced chlorosis. Nitrogen and K in leaf tissue increased in all treatments as fertilizer of that mixture was increased but P decreased.

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Ewell Rogers

Abstract

Sodium ferric ethylenediamine di-(o-hydroxphenylacetate) at 113.4 g per tree depressed the concn of Mn, Zn, P, K, and N in ‘July Elberta’ peach leaves and reduced Fe chlorosis. At 226.8 g, the chelate increased the concn of Fe; depressed the concn of Mn, Zn, and K; and reduced Fe chlorosis in the leaves. The Mn-Fe ratio remained essentially the same in the leaves as the season progressed where no fertilizer was applied; whereas, the 226.8 g rate of FeNa2-EDDHA reduced the ratio. There were no discernable treatment effects on trunk and shoot growth.

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Youbin Zheng, Diane Feliciano Cayanan, and Mike Dixon

replications (30 subsamples). Points for the same day bearing the same letter (beside the symbol) indicate that the means are not significantly different at the P ≤ 0.05 level. During the last week of the experiment, there was interveinal chlorosis on

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Crysta N. Harris, Ryan W. Dickson, Paul R. Fisher, Brian E. Jackson, and Anissa M. Poleatewich

general symptoms of leaf chlorosis and yellowing, and symptoms matched descriptions of N deficiency reported for petunia by Gibson et al. (2007) . Shoot tissue was also analyzed for other plant essential elements, which were also below the recommended

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Touria E. Eaton, Douglas A. Cox, and Allen V. Barker

, had severely chlorotic terminal leaves and branches ( Figs. 2 and 3 ). Fig. 2. Close-up of iron (Fe) deficiency induced chlorosis occurring on calibrachoa grown with oilseed extract fertilizer. Fig. 3. Calibrachoa plant grown with chemical fertilizer

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Giuseppe Cimò, Riccardo Lo Bianco, Pedro Gonzalez, Wije Bandaranayake, Edgardo Etxeberria, and James P. Syvertsen

overaccumulation of carbohydrates in leaves ( Bove, 2006 ; Garnier and Bove, 1983 ). The earliest visible symptoms of HLB in leaves are vein yellowing and asymmetrical chlorosis referred to as “blotchy mottle,” thought to be the result of starch accumulation