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Shiv D. Sharma and M. Singh

Various combinations of glyphosate and 2,4-D (± surfactant) were evaluated for control of Brazil pusley [Richardia brasiliensis (Moq.) Gomez]. Typical 2,4-D symptoms on plants were manifested within 2 to 3 days after treatment. Application of glyphosate alone had only marginal effects (14%) on Brazil pusley, but the addition of Induce® (nonionic surfactant) significantly increased control to 83% and reduced the fresh weight by 68%. Application of Landmaster®II or a tank-mix of glyphosate + 2,4-D (± surfactants) resulted in 96% to 100% control. Treatment with 2,4-D alone, or with Induce®, or L-77® (organosilicone surfactant) resulted in 84%, 90%, or 100% control, respectively. Very low fresh weights of Brazil pusley were recorded when 2,4-D +Induce® or L-77®, Landmaster®II (± surfactants), or the tank-mix (± surfactants) were applied. In the regrowth studies, shoot weight was greater following application of glyphosate with or without L-77® or Kinetic® (a blend of nonionic and organosilicone) than following other treatments. The fresh weight of the shoots in the regrowth study, recorded following the application of 2,4-D or Landmaster®II (± surfactants), was very low except when Kinetic® was added to Landmaster®II. No regrowth of shoots occurred following the tank-mix treatment. Similar observations were recorded for roots. Plants treated with 2,4-D did not regrow. The presence of 2,4-D in either formulation accelerated synergistic effect of the glyphosate to the target site. Therefore, 2,4-D could be used either as a component of a formulation or in a tank-mix with glyphosate to control Brazil pusley. Chemical names used: N-(phosphonomethyl glycine) (glyphosate); 2,4-dicholorophenoxyacetic acid (2,4-D).

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David Bubenheim, Kanapathipillai Wignarajah, Wade Berry, and Theodore Wydeven

Recycling wastewater containing soaps and detergents for plant growth is highly desirable when fresh water is limited. This is especially true during times of drought and is imperative in some specialized situations such as a regenerative space habitat. To regenerate food, water, and air, the National Aeronautics and Space Administration's Controlled Ecological Life Support System (CELSS) must recycle wastewater commonly known as gray water. The anionic surfactant Igepon is the principal ingredient of many detergent formulations and soaps and is a prime candidate for use in a space habitat. To determine if gray water would have phytotoxic effects on crops grown in a CELSS, `Waldmann's Green' lettuce (Lactuca sativa L.) was grown in nutrient solutions containing varying concentrations of Igepon TC-42. Igepon concentrations of 250 mg·L-1 or higher in nutrient solutions resulted in phytotoxic effects in lettuce. Thus, the toxic threshold of Igepon is <250 mg·L-1. Toxicity symptoms include browning of the roots within 4 hours of exposure to Igepon followed by suppression of root dry mass within 24 hours. Plant death never resulted from exposure to Igepon used in these experiments, although roots were killed. The phytotoxic effect of Igepon was not persistent; plants initially displaying acute toxicity show clear signs of recovery within 3 days of initial exposure. Further, when fresh plants were exposed to these same nutrient solutions 3 days or more following initial Igepon addition, no phytotoxic effect was observed. The elimination of the phytotoxicity was associated with a decrease in fatty acid components in the nutrient solution associated with Igepon. The degradation of phytotoxicity appears to be associated with microbes present on the surface of the roots and not directly due to any plant process or instability of the surfactant.

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Feras Almasri, Husein A. Ajwa, Sanjai J. Parikh, and Kassim Al-Khatib

methods have indirectly led to improving molecular diffusion of fumigants and their persistence in soils ( López-Fernández et al., 2016 ). It has been reported that the efficacy of Met-Na was improved when applied with the soil surfactant Integrate

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Michael W. Olszewski, Samara J. Danan, and Thomas J. Boerth

Surfactants increase wettability of pine bark and may be required in coarse substrates to enhance lateral movement of water and reduce infiltration rate through a container ( Bilderback, 1993 ). Cid-Ballarin et al. (1998) hypothesized that

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Robert A. Saftner, J. George Buta, William S. Conway, and Carl E. Sams

ICI Surfactants, Wilmington, Del., for samples of Atlox 8916TF, Brij 93 and 98 and Renex 30 and 36; OSi Specialties, Inc., Tarrytown, N.Y., for samples of Silwet L-77 and L-7604; Union Carbide Corp., Danbury, Conn., for samples of Tergitol 15-S-3

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John Sloan* and Wayne Mackay

Soils exhibit a degree of hydrophobicity and can repel water rather than absorb it. Surfactants lower the surface tension of water which may increase its infiltration into the soil and adsorption to soil solids. The objective of this study was to determine if water treated with a surfactant would increase conserve soil moisture and decrease the amount of water needed to sustain healthy plant growth. Clay and sandy loam soils were placed in 15-cm greenhouse pots. Impatiens seedlings were transplanted into each pot. All pots were fertilized equally and the Impatiens flowers were allowed to grow for 8 weeks. Then the pots were treated with tap water or tap water mixed with a commercial surfactant at one times (1×) or two times (2×) the recommended rate. After applying the water treatments, pots received no additional water. Each pot was weighed twice per day and the plants were observed for signs of wilting. Upon initial signs of wilting, each plant was rated on a scale of 1 to 3 with 1 = no wilting, 2 = leaves starting to droop, and 3 = wilting leaves and stems. Addition of the surfactant at the 1× and 2× rates slowed the loss of water from both the sandy loam and the clay soils. The effects of the surfactant were apparent within 3 to 5 days in the sandy loam soil and 6 to 10 days in the clay soil. The benefits of reduced water loss from soil were manifested by reduced wilting in Impatiens plants in soils treated with 1× and 2× the recommended rate of surfactant. In the clay soil, use of the surfactant increased the amount of time before Impatiens plants began to wilt. It appears that adding a surfactant to irrigation water can conserve soil moisture and extend the time between water applications.

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Matthew D. Madsen, Michael A. Fidanza, Nicholas S. Barney, Stanley J. Kostka, Turmandakh Badrakh, and Mica F. McMillan

–oxirane copolymers was effective at improving seedling emergence and plant growth in water repellent soils. This surfactant chemistry was patented by Kostka and Schuermann (2008) and is distributed under the trade name SET-4001 (Aquatrols Corporation of America

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Daniel K. MacKinnon, Dale Shaner, Scott Nissen, and Phil Westra

it to a crop by a conventional sprayer presents many challenges. The effectiveness of 1-MCP in field applications will be influenced by many factors, including spray volume, surfactants, and spray nozzle types, perhaps more so than with other

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K. Wignarajah, David Bubenheim, Theodore Wydeven Jr., Wade Berry, and Greg Schlick

Anionic surfactants are the major class of surfactants used in detergent, laundry and related industries. Hence, they are a major contaminate of both domestic and industrial waste streams. Lettuce (Lactuca sativa cv Waldemann's Green) was grown in nutrient solutions with the addition of the anionic surfactant, Igepon TC-42. The toxic response of lettuce to Igepon was that the roots turned brown and became necrotic within 24 h following exposure. Growth was supressed for approximately 4 days following exposure to concentration greater than 0.35 mM; new roots formed rapidly and growth resumed. When fresh plants were transferred to the solutions containing Igepon 48 h following introduction of the surfactant no signs of toxicity were observed. This would indicate that either the first series of plants absorbed the toxic material or the Igepon was decayed or degraded in the nutrient solution. The rapid recovery of plants from this stress suggests the potential of a wide range of strategies that could be developed for utilizing waste streams containing anionic surfactants.

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R.C. Ebel, D.G. Himelrick, A. Caylor, and J. Pitts

The surfactant “Surfactant WK” (dodecyl ether of polyethylene glycol) was applied to peach trees [Prunus persica (L.) Batsch] at full bloom over 3 years. Blossoms died rapidly so that within 2 days dead blossoms could be distinguished easily from live blossoms or set fruit. There were strong (R 2 > 0.87), linear correlations between concentration of “Surfactant WK” applied and percent blossoms removed and fruit set, which were similar over the 3 years. Trees were hand-thinned according to commercial practices after treatment. There was similar cropload, fruit weight, and yield across treatments at harvest indicating no negative effects by the chemical on productivity. There was only slight limb damage at the highest concentrations of “Surfactant WK,” which overthinned blossoms. We recommend that based on the effectiveness, consistency, and lack of significant phytotoxicity, “Surfactant WK” be reevaluated as a thinning chemical for peach trees.