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Joe DeFrank* and James J.K. Leary

Two experiment were conducted in 1999 and 2000 to determine the response of orchid cultivars, grown as potted plants, to postemergence herbicides. In a film covered commercial nursery in Pahoa, four orchid cultivars were exposed to five sequential herbicide applications. The cultivars used were: Emma White (Dendrobium), Wildcat Blood Ruby, Volcano Queen (both Oncidiums), and SuFun Beauty (Vanda). The herbicides evaluated in this experiment were diuron and clopyralid applied at the anticipated (1×), 2×, and 4× use rate. Spray applications were made directly to crop foliage using a spray to wet application. The first application was applied on 11 Nov. 1999 with sequential applications made at 20-, 208-, 73-, and 69-day intervals for a total of five sprays. Orchid dry weight accumulation was not significantly reduced and all cultivars responded in a similar way. “Emma White” was the only cultivar to express abnormal growth to clopyralid in the form of J-shaped flower spikes and deformed flowers. The other three cultivars did not show any noticeable injury in response to any of the spray applications. A follow up experiment was conducted on the dry leeward coast of Oahu in a commercial saran house. Diuron was the only herbicide evaluated at one and four times the anticipated labeled use rate. The first application was made on 27 Apr. 2000 with sequential applications made at 50-, 21-, 70-, and 66-day intervals for a total of five sprays. The orchids selected for this experiment included nine Dendrobiums and one Vanda. Treatments were made directly to plant foliage using a spray to wet application. Whole plant dry weight accumulation of the 10 cultivars responded in a similar way and no herbicide treatment reduced dry weight accumulation in comparison to untreated plants.

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Terri Woods Starman

One and two foliar spray and single-drench applications of uniconazole were applied to Eustoma grandiflorum (Raf.) Shinn (lisianthus) `Yodel Blue' to determine optimal concentrations for potted plant height control. A single uniconazole spray at 10.0 mg·liter-1 applied 2 weeks after pinching, two uniconazole applications at 5.0 mg·liter -1 applied 2 and 3 weeks after pinching, or a drench at 1.60 mg a.i. per pot applied 2 weeks after pinching gave equally good height control. At these concentrations, uniconazole was similar in its effect on plant height to daminozide foliar sprays at 7500 and 2500 mg·liter-l applied once and twice, respectively. Drenching with uniconazole at 1.60 mg a.i. per pot did not increase days to flower (DTF), whereas foliar spray applications did. Drenching did not reduce flower size, but increased flower number at time of harvest. Chemical names used: α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol); butanedioic acid mono(2,2-dimethylhydrazide) (daminozide);(E)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pent-1-ene-3-01 (uniconazole).

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Douglas C Needham and P. Allen Hammer

Salpiglossis sinuata R. et P., a floriferous member of the Solanaceae, was studied for potential as a flowering potted plant when modified by growth retardants. Seedlings of an inbred line P-5 were covered with black cloth for an 8-hour photoperiod to permit vegetative growth to ≈16 -cm-diameter rosettes. Plants were then exposed to an 18-hour photoperiod for the duration of study. Flowering occurred 40 days after the plants were transferred to long days. Neither spray applications of uniconazole at 10, 20, 40, or 100 ppm, nor chlormequat chloride at 750, 1500, or 3000 ppm significantly retarded plant height. Applications of daminozide, ranging in concentration from 1000 to 5000 ppm, alone and in combination with chlormequat chloride, were effective at retarding plant height; however, concomitant restriction of corolla diameter was frequently observed. Chemical names used: 2-chloro- N,N,N -trimethylethanaminium chloride (chlormequat chloride); butanedioic acid mono(2,2-dimethylhydrazide) (daminozide); and (E) -1-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl) -1-penten-3-01 (uniconazole).

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Esmaeil Fallahi and Brenda R. Simons

The influence of three rootstocks, various levels of soil-applied nitrogen in fall, and spring spray applications with and without minimum ground nitrogen on tree growth, productivity, leaf and fruit nutrient partitioning, and postharvest quality of fruit at harvest and after storage in `B.C. 2 Fuji' apple was studied over several seasons. Early results showed that trees on M.26 and M.9 were more precocious and had higher yield and yield efficiency. Trees on M.9 had significantly higher leaf Ca and incidence of sunburned fruit than those on other rootstocks. Trees on M.7 had larger fruit and higher leaf N, K, and Cu, but had lower fruit starch degradation pattern (SDP) and leaf Ca. Soluble solids at harvest were lower in fruit from trees on M.26 rootstock. Trees with fall nitrogen application had lower leaf N and better fruit color. Lower quantities of N application had smaller fruit but better fruit color and higher firmness at harvest. Fruit from all rootstocks did not produce ethylene for several days in the ripening chambers. After this period, fruit on M.9 rootstock produced ethylene before those from other rootstocks. Trees established with only nitrogen spray without any ground application had leaf N deficiency after they started bearing fruit. Establishment of a new `Fuji' orchard based on only nitrogen spray produced weak trees with low yield and yield efficiency, while addition of a small quantity of ground-applied N improved tree growth and fruit quality.

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T.J. Blom

Bract edge burn (BEB) has been observed in different greenhouse operations across North America over the past 10 years. The symptoms develop at anthesis or shortly after shipping. Varieties such as `Supjibi', `V-14 Glory', and `Celebrate 2' are considered susceptible cultivars. A number of trials using endosulfan (Thiodan) have been conducted. In 1993, `Supjibi' branched poinsettias were sprayed with either Thiodan, Decis, Thiodan + Decis, or water or remained unsprayed. The sprays were applied in week 39, 42 or 45. For each treatment period, plants were treated three times at 4-day intervals at label recommendations. At anthesis (week 47), plants sprayed with Thiodan or Thiodan + Decis during week 39 showed necrosis in the margin of the transitional bracts. In 1994, single spray applications in week 39, 40, 41, 42, or 45 of Thiodan, Ca (400 ppm), Thiodan + Ca in a tank mix, unsprayed, or Thiodan followed by four calcium sprays (weekly) in November. At week 48, all treatments except the latter showed necrosis, except this time it was marginal flecking in the transitional or primary bracts. In Spring 1995, single vs. multiple Thiodan applications were compared.

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J.G. Norcini, J.H. Aldrich, and J.M. McDowell

Foliar spray application of dikegulac at 1600 mg·liter-1 during production of Bougainvillea glabra Choicy `Mauna Kea White', and Bougainvillea `Raspberry Ice', `Royal Purple', `Summer Snow', and `Temple Fire' in 4.5-liter hanging baskets (25.4 cm in diameter) was investigated in relation to flowering. The effect of foliar-applied dikegulac at 0, 400, 800, 1200, and 1600 mg·liter-1 on bracteole size of `Mauna Kea White' was also determined. Liners of `Temple Fire' pruned at transplanting (0 weeks) and sprayed with dikegulac at, 0 and 4 weeks had increased flowering and a slightly more compact, pendulous growth habit than plants that had only been pruned at 0 and 4 weeks. Dikegulac had little to no effect on flowering of the other cultivars. Under late-spring to early summer conditions (generally increasing temperatures), bracteole size of `Mauna Kea White' was reduced ≈25 % by 400 mg dikegulac/liter compared to nontreated plants; 800 to 1600 mg dikegulac/liter reduced bracteole size ≈37%. Under late-summer to mid-fall conditions when the weather was cooler and wetter, dikegulac had little to no effect on bracteole size; however, bracteoles of nontreated plants were ≈25% smaller than those of plants grown under the warmer and drier conditions of late spring to early summer. Chemical name used: sodium salt of 2,3:4,6-bis -O- (1-methylethylidene) -α-l-xylo- 2-hexulofuranosonic acid (dikegulac).

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Brent L. Black, Martin J. Bukovac, and Jerome Hull Jr.

Post-bloom fruit thinning of spur-type `Delicious' with NAA may occasionally result in excessive small fruit (50 - 67 mm) not correlated with crop load. We evaluated the effect of carrier volume and time of application on incidence of small fruit over three growing seasons. A constant dose of NAA (30 g·ha-1) was applied in 230 to 2100 liter·ha-1 at about 10 mm king fruit diameter (KFD). Amount of NAA-induced small fruit differed from year to year, but there was no significant effect of carrier volume in any given year. NAA (15 mg·liter-1) was applied as a dilute spray at 5 to 22 mm KFD. Time of application influenced fruit size distribution at harvest in only one of three years. The incidence of small fruit appeared more closely related to temperature during spray application than to carrier volume or time of application. The effect of NAA on growth rate of king fruit with minimal competition (branches hand thinned, no lateral fruit) was determined over the first month after thinning. There was no pronounced effect of NAA on post-treatment growth rate. In a related study, NAA caused a significant decrease in fruit size when two or more fruit were competing on the same spur, while fruit size in the absence of intra-spur competition was not significantly reduced.

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J. Thomas Raese and S. R. Drake

Sprays of calcium materials were applied at high volume rates (620 g Ca/400 liters) with a handgun during early June, late June, and mid-July versus mid-July, early August, and late August for five years, 1985 to 1989. Leaf injury was most severe for the late sprays but no spray injury was observed on the fruit surfaces. Bitter pit was markedly reduced with all sprays except CaSO4. In some years, bitter pit was controlled better with the early sprays. Either early or late sprays improved fruit quality including overall appearance, reduced scald development, improved red color of the skin, increased fruit firmness and reduced incidence of bitter pit in cold air (0°C) storage. Soluble solids and acidity in the fruit was not affected by calcium sprays. Leaf Ca was higher from the late spray applications than from the earlier applications. All calcium chloride spray materials resulted in increased fruit peel and cortex Ca. Calcium nitrate sprays tended to increase fruit nitrogen concentrations leading to undesirable higher N:Ca ratios in the fruit.

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Anna Perkins Nina Bassuk

Budbreak inhibition and poor overwinter survival (OS) limit successful cutting propagation of Acer rubrum October Glory, A. rubrum Red Sunset, Hamamelis vernalis, H. virginiana and Stewartia pseudocamellia. Localized blanching (banding) of the cutting on the stock plant; a range of 3 IBA concentrations, and foliar spray application of: 1% silver thiosulfate(STS), STS followed ten days later by Gibberellin, GA4/7:250ppm(STS GA),50ppm thidiazuron (TDZ) and TDZ followed by GA4/7 (TDZ GA)were tested for increasing growth and overwinter survival.. Carbohydrates were analyzed in cuttings which did and didn't grow. A. rubrum October Glory*, and Hamamelis spp all had increased OS for cuttings which grew. A. rubrum Red Sunset demonstrated a similar trend. Hamamelis spp. had significant increase in carbohydrates for cuttings which grew. A. rubrum October Glory' exhibited the same trend. S. pseudocamellia did not have increased OS with growth. and showed no increases in carbohydrates with growth, but the cuttings that didn't grow had at least 93 % more carbohydrates than the other species analyzed. All species had higher OS when stored in the 3° C cooler, than in the fluctuating cold frame. Banding increased growth of A. rubrum October Glory, and H. virginiana. IBA concentration affected growth of all species. STS increased growth of H. virginiana and S. pseudocamellia. GA4/7 increased growth of all cuttings except A. rubrum October Glory.

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E.W. Stover, P.J. Stoffella, S.A. Garrison, D.I. Leskovar, D.C. Sanders, and C.S. Vavrina

A commercial mixture of 1-naphthaleneacetamide and 1-naphthaleneacetic acid (Amcotone) was applied to tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.) at various timings from early bloom through early fruit development to evaluate effects on fruit size and both early and total marketable yield. Amcotone was applied at rates from 10 to 40 mg·L-1, at three sites for each of the species studied. Measured yield response variables in tomato did not differ between the control and Amcotone treatments, regardless of location. Amcotone treatments did not affect yields or fruit size for pepper at the New Jersey or Texas sites. However, at Ft. Pierce, Fla., early marketable yield of pepper was increased in plots receiving three Amcotone applications at 10 mg·L-1, but total marketable yield was significantly reduced in all plots receiving more than two Amcotone sprays, and mean fruit weight was reduced by all Amcotone treatments. Early and total marketable yield of pepper at Ft. Pierce were markedly reduced in plots receiving four applications of 40 mg·L-1, which was a high rate used to assess potential phytotoxicity. While minimal benefit from auxin application was observed in this study, earlier studies suggest that these results may have been influenced by favorable environmental conditions for fruit development or negative effects on unopened flowers during all Amcotone spray applications.