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Valtcho D. Zheljazkov, Tess Astatkie, and Ekaterina Jeliazkova

, 1999 ). On the other hand, Tween20 has also been investigated as a means for improving essential oil content of some aromatic plants ( Dobreva et al., 2011 ). There are no studies in the literature whether foliar application of Rocky Mountain juniper or

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Atsushi Kono, Akihiko Sato, Bruce Reisch, and Lance Cadle-Davidson

inoculated onto new detached leaves as above for maintenance and propagation. Effect of Tween 20 on the recovery of sporangia from plastic ware. Sporangia suspension in water (300 μL of ≈1.5 × 10 5 sporangia/mL) was subsampled into 5 sets of 12

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Ryan N. Contreras

150 μM oryzalin (supplied as Surflan ® AS; United Phosphorus, Trenton, NJ) + 0.1% Tween ® 20 (Acros Organics, Geel, Belgium) using a standard household spray bottle that created a fine mist. Each species was replicated once per treatment duration for

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Stéphane Roy, William S. Conway, J. George Buta, Alley E. Watada, Carl E. Sams, and William P. Wergin

`Golden Delicious' apples (Malus domestica Borkh) were dipped in either distilled water, methylene chloride, or one of the following surfactants: Brij 30, Tween 20, Tween 80, Tergitol 15-S-9, and Triton X-100. The fruit then were pressure-infiltrated with a 2% solution of CaCl2. Following 4 months storage at 0 °C, fruit were removed and flesh Ca concentration analyzed. The fruit surface was observed using low-temperature scanning electron microscopy, and fruit were rated for surface injury. Brij 30 altered the epicuticular wax the least and resulted in the smallest increase in flesh Ca concentration and the softest fruit. Triton X-100 altered the epicuticular wax the most and resulted in the highest fruit flesh Ca concentration and firmest of the surfactant-pretreated fruit. Methylene chloride removed some of the epicuticular wax, and fruit pretreated with this solvent had the highest flesh Ca concentration and greatest firmness. However, all of the fruit treated with methylene chloride were severely injured.

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Moritz Knoche and Martin J. Bukovac

The effects of selected surfactants and surfactant blends, frequently used in spray application, on deposit formation and foliar absorption of GA3 by sour cherry (Prunus cerasus L. cv. Montmorency) have been investigated. Globular deposits were observed on droplet drying from solutions without surfactants or when the surfactants Activator 90, Tween 20, or Silwet L-77 were present, while annular-shaped deposits were observed with Regulaid, Ortho X-77, and Triton AG-98. Absorption of GA3 without surfactant was 5- and 17-fold higher by the abaxial (8.5% and 20.2% of applied in 1988 and 1989) than adaxial surface (1.6% and 1.2% of applied in 1988 and 1989). Over 24 hours, Ortho X-77 and Activator 90 (45.7% vs. 33.7% in 1988, 42.5% vs. 41.7% in 1989) were most effective in enhancing GA3 penetration through the abaxial surface, followed by Triton AG-98 (38.6% in 1988), Tween 20 (28.6% in 1989), and Regulaid (23.6% in 1988, 16.8% in 1989). Silwet L-77 significantly reduced GA3 uptake (10.7% in 1989) compared with the nonsurfactant control (18.2% in 1989). GA3 uptake increased at a decreasing rate during a 96-hour absorption period when GA3 was applied alone or with Ortho X-77. However, uptake increased linearly with time in the presence of Regulaid, yielding significantly higher GA3 penetration 96 hours after application (44.8%) compared with GA, alone (11.3%) or GA3 with Ortho X-77 (27.7%). GA3 penetration was independent of Tween 20 concentration in the range from 0.0313% to 0.25% but increased with increasing Ortho X-77 concentration (0.0313$%0 to 0.25%) over a 24-hour absorption period. Chemical names used: alkylpolyoxyethylene ether, free fatty acids, isopropanol (Activator 90); alkylarylpolyoxyethyleneglycols, free fatty acids and isopropanol (Ortho X-77); polyoxyethylenepolypropoxypropanol, alkyl 2-ethoxy-ethanol (Regulaid); polyalkyleneoxide modified polydimethylsiloxane copolymers (Silwet L-77); alkylarylpolyethylene glycol (Triton AG-98); polyoxyethylene (20) sorbitan monolaurate (Tween 20); gibberellic acid (GA3).

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Richard Marini

In five experiments with `Redchief Delicious' and one with `Braeburn', oxamyl (Vydate 2L) was used alone or combined with other chemicals to thin apples. The thinning response to oxamyl depended on dose. In most cases, oxamyl at 600 mg·L−1 and carbaryl at 900 mg·L−1 thinned trees similarly, but the combination of oxamyl plus carbaryl was no more effective than either chemical alone. The combination of oxamyl plus NAA (2.5 to 5 mL·L−1) was slightly more effective than either material alone. The thinning response to oxamyl and carbaryl was related to the concentration of superior oil added to the spray solution; for both chemicals, adding oil at 5 mg·L−1 or Tween 20 at 1.25 mL·L−1 gave equivalent thinning. Apples on trees sprayed with oxamyl plus oil had a dull finish. Adding Tween 20 at 1.25 mL·L−1 improved the thinning activity of carbaryl (Sevin XLR-Plus) more than oxamyl. Similar thinning occurred whether oxamyl was applied when fruit diameter averaged 4 or 10 mm. On `Braeburn' oxamyl, carbaryl, Accel, and NAA were mild thinners, but all combinations of oxamyl or carbaryl plus Accel or NAA overthinned the trees without improving fruit size. In general, oxamyl at 600 mg·L−1 (2 pints of vydate 2L/100 gal.) and carbaryl thin apple trees similarly, and the efficacy of both chemicals is improved by adding a surfactant.

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Dominic Durkin

Freshly harvested Rosa hybrida, `Kardinal' flowers were used to evaluate vase performance after hydration and storage at 37°F. Flowers were placed in one of six solutions for 24 hours and in dry storage for 3 additional days. After storage, half of the roses were cut before placement in vase solution containing 1% dextrose and potassium salts but without an anti-microbial agent.

Roses hydrated in aluminum sulfate had the shortest life followed by roses hydrated in CHRYSAL RVB. Flowers hydrated in CHRYSAL RVB and cut lasted as well as roses hydrated in HYDRAFLOR-100, 60 ppm sodium hypochlorite (naocl), citric acid, or citric acid with Tween 20 for one hour followed by 60 ppm maocl solution. Roses stored in naocl solution performed as well without, as with, cutting before placement in the vase solution. Results will be discussed in terms of microbe and particulate blockage of hydration pathways.

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Masood Z. Hadi, Mark P. Bridgen, and John P. Sanderson

Procedures were developed to determine if live, adult two-spotted spidermites (Tetranychus urticae Koch) could be surface disinfested before being introduced into in vitro cultures of torenia (Torenia fournieri L.). Three time periods (5, 10, and 15 minutes) and five levels of sodium hypochlorite (0.05% to 0.25%) were evaluated. Surface disinfestation was accomplished by agitating 2 × 3 cm pieces of infested bean leaves in sodium hypochlorite solutions and then drying in a mite drier apparatus. All sodium hypochlorite concentrations disinfested the mites completely, however high concentration levels were lethal to the mites. Exposure periods of 10 and 15 minutes also significantly increased mortality. For optimum disinfestation of two-spotted spidermites with minimum mortality, a concentration of 0.05% sodium hypochlorite and 0.05% Tween-20 for 5 minutes should be used.

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Shiow Y. Wang and Dean Der-Syh Tzeng

Foliar application of a mixture of methionine (1 mm) and riboflavin (26.6 μm) reduced the severity of powdery mildew [Sphaerotheca macularia (Wallr. ex Fr.) Jacz. f. sp. fragariae] infection in `Earliglow' strawberry (Fragaria × ananassa Duch.) plants. Efficacy of this mixture on controlling powdery mildew infection was enhanced by supplements of copper, iron, and surfactants [sodium dodecyl sulfate (SDS), Triton X-100, Tween-20, or oxyalkylenemethylsiloxane (Silwet L-77)]. Free-radical scavengers (n-propyl gallate, thiourea) and antioxidants (α-tocopherol, β-carotene) reduced the efficacy of this mixture. Plants treated with a mixture of riboflavin (26.6 μm), d,l-methionine (1 mm), copper sulfate pentahydrate (1 mm), and surfactants (SDS or Silwet L-77 at concentrations of 0.05% to 0.1%) showed a decrease in powdery mildew infection. Results of this study suggest that treatment with a mixture of methionine and riboflavin is beneficial to strawberry plants and may serve as an alternative to fungicides for controlling powdery mildew.

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Alice Spurlin Waegel

Shining club moss, Huperzia lucidula (Michaux) Trevisan, can be propagated in tissue culture, but it is difficult to obtain sterile explants. When standard disinfestation methods were used, 100% of H. lucidula apical shoot-tips disinfested for 10, 20, or 30 minutes with 1% sodium hypochlorite/0.15% Tween 20 became contaminated or browned within 3 weeks. Since this club moss is highly contaminated, a stepwise disinfestation procedure was developed to eradicate spore forming microbes. Based on the principle that vegetative microbial cells are more easily destroyed than spores, stepwise disinfestation induced spore germination before explant treatment with sodium hypochlorite. A 48-hour disinfestation treatment resulted in 50% explant survival without visible contamination. Fewer explants (22%) were successfully disinfested when a 24-hour stepwise disinfestation was used. Applying the stepwise disinfestation method to contaminated cultures after a standard disinfestation protocol produced an additional 15.6% contamination-free club moss shoot-tips. After successful surface disinfestation, H. lucidula shoot-tips and gemmae established in vitro grew normally.