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Maurizio Micheli, Daniel Fernandes da Silva, Daniela Farinelli, Graziana Agate, Rafael Pio and Franco Famiani

; Thorpe et al., 2008 ). We propose including neem oil among the “complex mixtures.” This oil, extracted from the seeds of Azadirachta indica (A. Juss.), has been known and used for a long time in agriculture, as a fertilizer, soil conditioner and

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Tracy Monique Magellan, Chad Husby, Stella Cuestas and M. Patrick Griffith

sexdens rubropilosa ) with negative results ( Miyashira et al., 2011 ) and on mosquito ( Aedes aegypti ) with positive results ( Guirado and Bicudo, 2007 ; Laranja et al., 2003 ). Prior studies indicated neem oil ( Fiaz et al., 2012 ; Mamoon-ur-Rashid et

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James D. Spiers, Fred T. Davies Jr., Chuanjiu He, Carlos E. Bográn, Kevin M. Heinz, Terri W. Starman and Amanda Chau

This study evaluated the influence of insecticides on gas exchange, chlorophyll content, vegetative and floral development, and plant quality of gerbera (Gerbera jamesonii Bolus `Festival Salmon'). Insecticides from five chemical classes were applied weekly at 1× or 4× their respective recommended concentration. The insecticides used were abamectin (Avid), acephate (Orthene), bifenthrin (Talstar), clarified hydrophobic extract of neem oil (Triact), and spinosad (Conserve). Photosynthesis and stomatal conductance were reduced in plants treated with neem oil. Plants treated with neem oil flowered later—and at 4× the recommended label concentration had reduced growth, based on lower vegetative dry mass (DM) and total aboveground DM, reduced leaf area, thicker leaves (lower specific leaf area), higher chlorophyll content (basal leaves), and reduced flower production. Plants treated with acephate at 4× the recommended label concentration were of the lowest quality due to extensive phytotoxicity (leaf chlorosis). Plants treated with 1× or 4× abamectin or spinosad were of the highest quality due to no phytotoxicity and no thrips damage (thrips naturally migrated into the greenhouse). The control plants and plants treated with 1× bifenthrin had reduced quality because of thrips feeding damage; however gas exchange was not negatively affected.

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Morgan L. Cromwell, Lorraine P. Berkett, Heather M. Darby and Takamaru Ashikaga

approved fungicides. Potassium bicarbonate (Eco-Mate Armicarb “O”; Helena Chemical Co., Collierville, TN; 85% a.i.), Bacillus subtilis strain QST713 (Serenade MAX; AgraQuest, Davis, CA; 14.6% a.i.), and clarified hydrophobic extract of neem oil (Trilogy

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Joseph G. Masabni and S. Alan Walters

College Station, TX, combined for both mushroom and city compost treatments. In 2010, 70% neem oil at 0.78% v:v (Green Light Neem Concentrate; Scott’s Miracle-Gro Co., Marysville, OH) and pyrethrin at 0.26% v:v (Bonide 857 Pyrethrin Spray Concentrate

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James D. Spiers, Fred T. Davies, Chuanjiu He, Carlos Bogran, Amanda Chau, Kevin M. Heinz and Terri W. Starman

This research focused on the influence of insecticides on gas exchange, chlorophyll content, vegetative and floral development, and overall plant quality of gerbera (Gerbera jamesonii var. `Festival Salmon'). Insecticides from five chemical classes were applied weekly at 1× and 4× the recommended concentrations. Insecticides used were: abamectin (Avid® 0.15 EC), acephate (Orthene® Turf, Tree & Ornamental Spray 97), bifenthrin (Talstar® Nursery Flowable), clarified hydrophobic extract of neem oil (Triact® 70), and spinosad (Conserve® SC). Phytotoxicity occurred in the form of leaf chlorosis on all acephate treatments, with the greatest damage occurring at the 4× concentration. Photosynthesis and stomatal conductance were significantly reduced in plants treated with neem oil extract. Plants treated with the neem oil extract (1× and 4×) flowered later and had reduced growth [lower shoot dry mass (DM) and total DM]. Plants that received 4× the recommended concentration of neem oil extract had reduced leaf area, thicker leaves (lower specific leaf area), higher leaf chlorophyll content, and reduced flower production, as determined by flower number and flower DM. Plants treated with acephate 4× concentration were the lowest quality plants due to extensive phytotoxicity (leaf burn), which also reduced photosynthesis. The highest quality plants were treated with spinosad and abamectin due to zero phytotoxicity and/or no thrips damage (thrips naturally migrated into the greenhouse). The control plants and plants treated with bifenthrin 1× were not marketable due to thrips damage; however, plant growth characteristics and gas exchange were not statistically different.

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Kenneth W. Cote, Edwin E. Lewis and Peter B. Schultz

The twospotted spider mite, Tetranychus urticae Koch, is a serious pest of many nursery crops. Regular acaricide applications are required to maintain acceptable population levels of this pest. Phytoseiulus persimilis Athias-Henriot is a commercially available predator used to control T. urticae populations. The effects of acaricide residues were tested on P. persimilis and T. urticae using a leaf disk system. Both species were exposed to residues for 24 hours 1, 3, 7, and 14 days after acaricide application. Abamectin, Gowan 1725, hexythiazox, horticultural oil, neem oil, pyridaben, and spionosyn residues caused no mortality to P. persimilis 1, 3, 7, or 14 days after application. Chlorfenapyr was harmful to both species at all times after application. Bifenthrin residue was toxic to P. persimilis at all times after application, but was only harmful to T. urticae up to one week after application. Tetranychus urticae mortality from Gowan 1725, horticultural oil, and neem oil residues was significantly greater than the control 24 hours after application, but not thereafter. Tetranychus urticae mortality from hexythiazox and spinosad residues was not significantly greater than the control. Proper pesticide selection may create favorable conditions for release of P. persimilis and reduce acaricide dependency.

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Harold E. Moline and James C. Locke

The antifungal properties of a hydrophobic neem (Azadirachta indica A. Juss.) seed extract (clarified neem oil) were tested against three postharvest apple (Malus domestica Borkh.) pathogens—Botrytis cinerea (pers.) ex Fr. (gray mold), Penicillium expansum Thom. (blue mold rot), and Glomerella cingulata (Ston.) Spauld. & Schrenk. (bitter rot). The antifungal activity of neem seed oil also was compared to that of CaCl2. A 2% aqueous emulsion of the clarified neem seed oil was moderately fungicidal to B. cinerea and G. cingulata in inoculated fruit, but bad little activity against P. expansum. Ethylene production was reduced 80% in fruit dipped in 2% neem seed oil compared to wounded, inoculated controls. Neem seed oil was as effective an antifungal agent as CaCl2, but the effects of the two combined were not additive.

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H.B. Pemberton, G.L. Philley and W.E. Roberson

Plants of Rosa L. `Peace' were field planted in Feb. 1995 in order to test black spot (Diplocarpon rosae Wolf) control efficacy of several compounds. Plants were protected from fungal infection by black spot with weekly sprays of chlorothalonil (Daconil) from 5 Apr. to 8 June 1995 to allow plant establishment. Spray treatments for efficacy testing were started on 23 June and ended on 1 Nov. 1995. All plants were uniformly weeded, fertilized, and irrigated as needed for the duration of the experiment. Plants were rated for defoliation and disease development on 18 July, 1 Sept., and 10 Nov. 1995. A wettable granular formulation of cyproconazole (Sentinel) controlled black spot significantly better when a surfactant, Latron B-1956, was added to the spray solution at 0.5 mL·L–1. Differences between treatments with and without surfactant were greater at lower rates vs. higher rates of cyproconazole. The most effective Sentinel rates with the surfactant were 0.13 g·L–1 applied every 14 days or 0.26 g·L–1 every 21 days. A formulated combination of chlorothalonil and thiophanate methyl (ConSyst) controlled black spot on a 7-day interval at 1.2 g·L–1, but not when applied at 1.8 g·L–1 every 14 days. Control was no better than the standard mancozeb (Dithane) treatment. Neem oil (NeemGard) was not effective on the 14-day schedule tested. Tank mixing neem oil with chlorothalonil or thiophanate methyl (Domain) did not significantly improve control. Neither myclobutanil (Systane) or a formulated combination of mancozeb and myclobutanil (RH 0611) was effective in controlling black spot.

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D. Grant McCarty II, Sarah E. Eichler Inwood, Bonnie H. Ownley, Carl E. Sams, Annette L. Wszelaki and David M. Butler

, Oro Valley, AZ) and extract of neem oil (70% neem oil; Monterey Lawn and Garden Products, Fresno, CA) as necessary. At first harvest, recently matured leaves were collected from each treatment, dried at 65 °C, and TN determined by combustion as