Soybean Oil as a Summer Spray for Apple: European Red Mite Control, Net CO2 Assimilation, and Phytotoxicity

Abstract

<jats:p>Soybean [<jats:italic>Glycine max</jats:italic> (L.) Merrill] oil was applied to apple trees [<jats:italic>Malus sylvestris</jats:italic> (L.) Mill var. <jats:italic>domestica</jats:italic> (Borkh.) Mansf.] as a summer spray in six studies to determine if it controls European red mites [<jats:italic>Panonychus ulmi</jats:italic> (Koch.)], how it affects net CO<jats:sub>2</jats:sub> assimilation (A), and if it causes phytotoxicity. Sprays of 0.5%, 1.0%, and 1.5% soybean oil {TNsoy1 formulation [soybean oil premixed with Latron B-1956 (LAT) spreader-sticker at 10 oil: 1 LAT (v/v)]} reduced mite populations by 94%. Sprays of 1% and 2% soybean oil reduced mite populations to three and four mites per leaf, respectively, compared to 25 per leaf on water-sprayed plants. Soybean oil concentrations of 1.0% and 1.5% applied to whole trees reduced A for less than 7 days. Phytotoxicity did not occur when soybean oil was applied with an airblast sprayer at concentrations of 1.0% and 1.5% or with a mist bottle at 2%. Phytotoxicity occurred when soybean oil was applied with a mist bottle at 4% and 6%, which left soybean oil leaf residues of 0.22 to 0.50 mg·cm<jats:sup>-2</jats:sup>. No phytotoxicity occurred with 4% SunSpray, which resulted in a mean leaf residue of only 0.13 mg·cm<jats:sup>-2</jats:sup>. Spraying 1% soybean oil tended to give better mite control than 1% SunSpray Ultra-Fine oil, but caused greater oil residues and a greater reduction in A.</jats:p>

Phytotoxicity of GF‐120® NF Naturalyte® fruit fly bait carrier on sweet cherry (Prunus avium L.) foliage

“…The majority of the studies were on soybean oil, reportedly less phytotoxic than petroleum‐based or mineral oils 15, 16, 22. The acute phytotoxicity observed on cherry leaves has also been reported for soybean oil applications on apple,17 dandelion15 and grape;16 in most cases, damage increased with increasing concentration. When applied directly to soybean leaflets, propylene glycol was not phytotoxic at concentrations up to 10%,21 yet did cause chlorosis and necrosis on soybean and corn leaves when introduced in vapour form in a controlled chamber 20…”

“…Of the ingredients known to be in the bait matrix, soybean oil and propylene glycol have been previously investigated for potential phytotoxicity on a variety of crops,14–21 although other ingredients, such as ammonium acetate, have not been ruled out as potential contributing factors. The majority of the studies were on soybean oil, reportedly less phytotoxic than petroleum‐based or mineral oils 15, 16, 22.…”

Impact of physical characteristics of some mineral and plant oils on efficacy against selected pests

“…1995; Hix et al. 1999) and European red mite (Moran et al. 2003) on apple trees and terrapin scale ( Mesolecanium nigrofasciatum ) on peach trees (Sams and Deyton 2002).…”

Late dormant rapeseed oil treatment against black cherry aphid and cherry fruit moth in sweet cherries

“…Mineral oil has been tested against adult, nymph and eggs and as a oviposition deterrent of arthropod pests (Chapman 1967; Agnello et al. 1994; Moran et al. 2003; Fernandez et al.…”

“…Application of dormant mineral oil against insect and mite pests has been used for decades (Chapman et al 1941;Chapman and Pearce 1949;Schøyen and Jørstad 1956;Chapman 1967). Mineral oil has been tested against adult, nymph and eggs and as a oviposition deterrent of arthropod pests (Chapman 1967;Agnello et al 1994;Moran et al 2003;Fernandez et al 2005). Knowledge of the effects of vegetable oil as a pesticide is more scarce.…”