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Moritz Knoche, Norman K. Lownds, and Martin J. Bukovac

Effect of carrier volume (range 119 to 668 L·ha-1) on dose response relationships of daminozide and GA3 was investigated using bean (Phaseolus vulgaris L.) seedlings as a model system. Carrier volume was varied by altering nozzle travel speed thereby maintaining constant flow rate and droplet size. Response was indexed by inhibition (daminozide) or stimulation (GA3) of elongation of first plus second internodes above primary leaves 14 days after spray application. Increasing dose by increasing concentration and/or increasing carrier volume at constant concentration increased response. For a given dose retained, response to daminozide was related positively to carrier volume, while GA3 response was not affected. Chemical names used: butanedioic acid mono(2,2-dimethylhydrazide) (daminozide); gibberellic acid (GA3).

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Daniel Leskovar, Shinsuke Agehara, and Smiljana Goreta

The objective of this study was to determine the effects of 1-MCP preharvest spray application on harvest synchrony, maturity, fruit quality, and marketable yield of cantaloupe. Seeds were planted in a commercial field on 16 Mar. (early planting, cv. Caravelle) and 4 Apr. (late planting, cv. Mission) 2005. Standard plant population, fertilization, irrigation, and pest control practices were followed. We evaluated three 1-MCP rates (5, 10, or 25 g·ha-1 a.i.) at three preharvest spraying times for the early (22, 15, and 7 days before harvest, DBH) or once for the late planting experiment (4 DBH). An additional test (late planting) compared fruit quality after storage for melons dipped with 1-MCP (0 or 10 mg·L-1). Fruits were harvested six times during June 2005 (early planting) and once on 19 July 2005 (late planting) and fruit quality parameters were measured at harvest and after storage. The preharvest 1-MCP application slightly delayed maturity and improved early harvest synchrony, but did not affect total marketable or yield by fruit size regardless of timing or rate of application. There was no effect of 1-MCP rate or application timing on fruit quality at harvest or after cold storage, except for an increased in fruit firmness (10%) in one of the six harvests. However, fruits treated with 1-MCP spray at 25 g·ha-1 a.i. (late planting) had higher firmness than those treated with lower rates after 9 days of storage. In addition, 1-MCP postharvest dipping significantly improved fruit firmness; however, a `greening' was evident in the fruit surface. Our results suggest that cantaloupe fruit quality was less affected by early preharvest spray application of 1-MCP applied at less than 25 g·ha-1 a.i. as compared to postharvest applications.

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S.M. Southwick, W. Olson, J. Yeager, and K.G. Weis

During the fruit growing season, April through August 1990, 1991, and 1992, four sprays of 20-22 liters/tree of KNO3 were applied to `French' prune trees (Prunus domestica L. syn. `Petite d'Agen). Spray applications of KNO3 were compared to single annual soil applications of KCl (1.4-2.3 kg/tree) and sprays of urea + KNO3 with respect to leaf K and N, fruit size, drying ratio, and dry yield. Potassium nitrate sprays were as effective, or better, than soil-applied K in maintaining adequate levels of leaf K throughout the season. Treatment effects were not carried over into the next year. Lowest leaf K was found in trees where no K had been applied. Those values were below the adequate level of 1.3% K and the untreated group developed K deficiency symptoms. Consistent effects on leaf K were not obtained when urea was applied and no negative effect on leaf K was demonstrated. Equivalent dry yields per tree were obtained by foliar and soil K applications. There was no best time for KNO3 sprays. Yield per tree was not enhanced when foliar K-N sprays were applied to trees that had levels of 1.3% K or more as of 15 Apr. 1992. Trees that were below optimum K in April tended toward improved dry yields after four K-N sprays. Trees that had no applied K were lowest yielding. Drying ratios and fruit size (number of fruit per kilogram) were not different among K treatments. Dry yields per tree were increased without a decrease in fruit size or an increase in drying ratio with either soil or foliar K application. These results suggest that foliar KNO3 sprays applied four times throughout the growing season can be used to correct incipient K deficiency in `French' prune and to obtain dry yields equivalent to those obtained with soil applications of KCl.

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C.R. Unrath

The canopy of an apple orchard can be objectively quantified by using tree height and cross row limb spread to calculate the tree row volume (TRV). Use of the appropriate water rate, adjusted for canopy density, is an effective tool for determining full dilute water rate for airblast applications. To save run off most dilute pesticides are applied at 70% of TRV. TRV model use will be discussed and illustrated. Comparison of handgun vs airblast applications showed more deposition and thinner activity w/handgun. Thinners applied at a fixed concentration of a.i. showed decreased activity as volume decreased. Applications at the same a.i./ha, regardless of water volume showed similar activity at and below TRV water and reduced activity at higher than TRV water, indicating activity loss from run off. Added testing showed uniform thinner activity only if water volume was within ± 20% of tree TRV rate. A fruit dip experiment showed greatly differing natural fruit drop but similar added chemical induced fruit drop between top, lower outside and lower inside of apple trees, a factor which must be adjusted for w/nozzle distribution on large trees.

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Anil P. Ranwala, Garry Legnani, and William B. Miller

Several experiments were conducted to find effective ways of utilizing gibberellin4+7 (GA4+7) and benzyladenine (BA) to prevent leaf chlorosis during greenhouse production of Easter lilies (Lilium longiflorum Thunb.) while minimizing the undesirable side effects on stem elongation. On an absolute concentration basis, GA4+7 was much more effective than BA in preventing leaf chlorosis. Excessive levels of GA4+7, however, tended to cause stem elongation. When applied at around the visible bud stage, if the foliage was well covered with the spray solution, 25 mg·L-1 of GA4+7 was adequate for maximum protection against leaf chlorosis. Increasing the GA4+7 concentration above 25 mg·L-1 gave no additional benefit on leaf chlorosis. Two possible modes of GA4+7 uptake during a foliar spray application (absorption through leaves and stems, and root uptake of the extra run-off) were studied in terms of their relative contribution to leaf chlorosis and stem elongation. Although both modes of uptake prevented leaf chlorosis, foliar uptake was much more effective than root uptake. However, GA4+7 taken up by the roots contributed mainly to stem elongation. When sprayed to leaves on only the lower half of the plant, a 10-mL spray of either 25 or 50 mg·L-1 of each GA4+7 and BA was enough for complete protection against leaf chlorosis. Increasing volumes had no additional benefit on leaf chlorosis, but increased the chances of unwanted stem elongation.

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Wayne C. Porter and Richard L. Parish

Concerns over ground water, nonpoint pollution, and soil erosion have indicated a need for reduced use of preemergent herbicides and reduced tillage. This study was initiated to determine the feasibility of using postemergent, burndown herbicides under hooded sprayers in the production of southernpeas. Two rates of paraquat, glufosinate, and glyphosate were applied at two application timings. All herbicides controlled rice flatsedge but not goosegrass. Since an untreated strip was left surrounding the drill, complete weed control did not occur in this system. In most cases, delaying application of the herbicides by 2 weeks tended to result in lower yields. However, no differences from a delay in cleaning the hoed check were noted. Plots treated with paraquat at 1.0 pt/A – timing 1 and glufosinate at 7.0 lb a.i./A – timing 2 had yields lower than the hoed check. Based on this study, southernpeas can be grown successfully without the use of a preemergent herbicide by proper timing of a hooded application of a burndown herbicide with proper timing.

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Eugene K. Blythe, Jeff L. Sibley, Ken M. Tilt, and John M. Ruter

In five experiments, singlenode cuttings of `Red Cascade' miniature rose (Rosa) were treated with a basal quick-dip (prior to insertion into the rooting substrate) or sprayed to the drip point with a single foliar application (after insertion) of Dip `N Grow [indole-3-butyric acid (IBA) + 1-naphthaleneacetic acid (NAA)], the potassium salt of indole-3-butyric acid (K-IBA), or the potassium salt of 1-naphthaleneacetic acid (K-NAA); a single foliar spray application of Dip `N Grow with and without Kinetic surfactant; or multiple foliar spray applications of Dip `N Grow. Spray treatments were compared with their respective basal quick-dip controls {4920.4 μm [1000 mg·L-1 (ppm)] IBA + 2685.2 μm (500 mg·L-1) NAA, 4144.2 μm (1000 mg·L-1) K-IBA, or 4458.3 μm (1000 mg·L-1) K-NAA}. Cuttings sprayed with 0 to 246.0 μm (50 mg·L-1) IBA + 134.3 μm (25 mg·L-1) NAA, 0 to 207.2 μm (50 mg·L-1) K-IBA, or 0 to 222.9 μm (50 mg·L-1) K-NAA resulted in rooting percentages, total root length, percent rooted cuttings with shoots, and shoot length similar to or less than control cuttings. Exceptions were cuttings sprayed with 0 to 2.23 μm

(0.5 mg·L-1) K-NAA, which exhibited shoot length greater than the control cuttings. Addition of 1.0 mL·L-1 (1000 ppm) Kinetic organosilicone surfactant to spray treatments resulted in greater total root length and shoot length. Repeated sprays (daily up to seven consecutive days) had no or negative effects on root and shoot development.

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Robert M. Frymire and Janet C. Henderson

Uniform liners of pyracantha (Pyracantha coccinea Roem `Lalandei'), photinia (Photinia × fraseri Dress) and dwarf Burford holly (Ilex cornuta Lindl. and Paxt. `Burfordii Nana') were potted into 3.8 liter containers in a pine bark:sand medium. Ten weeks later, plants received uniconazole treatments as a media drench or foliar spray. The uniconazole drench rates were 0, 0.5, 1.0, and 3.0 mg ai per container for all three plant species. The foliar application rates were 0, 50, 100 and 150 ppm for pyracantha, 0, 25, 50 and 100 ppm for photinia, and 0, 10, 25, and 50 ppm for dwarf Burford belly. Plant heights and widths were recorded at 3 week intervals, and leaf chlorophyll content was determined by calorimeter at the same time as height and weight measurements. At harvest, leaf counts, leaf areas, and shoot, leaf and root dry weights were determined. Initial results indicate that both foliar and media drench treatments of uniconazole reduced growth of pyracantha and photinia at all rates. Only the two highest rates decreased growth of dwarf Burford holly when applied as either a media drench or a foliar spray.

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Garry V. McDonald* and Michael A. Arnold

Previous experiments indicated that plant growth regulators applied during greenhouse production can have a negative effect on subsequent landscape performance of pansy (Viola × wittrockiana H. Gams `Crown Yellow'). Three experiments were initiated in September 2003 to determine the affects of paclobutrazol and ancymidol on production and landscape performance of ornamental cabbage (Brassica oleracea L. var. acephala A.P. deCandolle `Dynasty Pink'), calendula (Calendula officinalis L. `Bon Bon Orange'), and pansy. Seeds were germinated in plug trays (1.5 cm3 inverted cone-shaped pockets) in a growth chamber with a 12 h photoperiod at 25/21 °C day/night. Plants were sprayed with paclobutrazol (formaulated as Bonzi) or ancymidol (formulated as Arest) at plug stage (cabbage, pansy, and calendula on 25 Sept., 2 Oct., 11 Nov., respectively), at 14 days after transplant into 0.73 L containers, or at both stages. Paclobutrazol was applied at 0, 5, 10 or 15 mg·L-1 and ancymidol at 0, 2, 4, or 8 mg·L-1. Cabbage (30 Oct.), pansy (6 Nov.), and calendula (4 Dec.) were transplanted to landscape beds to assess residual effects on growth and flowering. Cabbage and calendula, showed minor differences in growth during greenhouse production due to varying rates of either paclobutrazol or ancymidol, but exhibited a greater response to application time. Only minor differences in growth occurred with pansy during greenhouse production due to rate or time of application using ancymidol, but exhibited major differences in response to both rate and time of application using paclobutrazol. Residual effects on growth and flowering during landscape performance phase will be discussed.

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Gang Li and Michael R. Evans

Seedlings of Cucumis sativus (cucumber), Tagetes patula (marigold), Viola tricolor (pansy), Pelargonium × hortorum (geranium), and Impatiens wallerana (impatiens) were germinated on towels soaked with either deionized water, nutrient control solutions, or humic acid solutions. Root fresh weight and root dry weights were higher for all seedlings germinated on towels soaked with humic acid as compared to seedlings germinated on towels soaked with deionized water or nutrient control solutions. Lateral root number and total lateral root length were higher for cucumber, marigold, pansy, and geranium seedlings germinated on towels soaked with humic acid than those germinated on towels soaked with deionized water or nutrient control solutions. Root fresh and dry weights were higher for impatiens, Begonia semperflorens (begonia), marigold, and geranium seedlings germinated in a sphagnum peat: vermiculite (80:20, %v/v) substrate drenched with humic acid as compared to seedlings germinated in substrate drenched with deionized water or nutrient control solutions. Foliar sprays of humic acid also resulted in increased root fresh and dry weights while foliar application of nutrient control solutions either had no effect or reduced root fresh and dry weights.