Research ArticleArticles

Spray Adjuvants Are Management Tools

T.E. “Ted” Whitmore
Arboriculture & Urban Forestry (AUF) March 1986, 12 (3) 57-65; DOI: https://doi.org/10.48044/jauf.1986.013

Article Figures & Data

Figures

  • Figure 1.
    Figure 1.

    Surfactant molecules break the surface tension of water when the water repellent ‘head’ protrudes through the water surface. The greater the number of molecules the more surface tension is reduced.

  • Figure 2.
    Figure 2.

    Drops of water on waxed paper: (a) no surfactant, (b) with 1 pint Ortho X-77® (non-ionic spreader) and (c) with 2 pints Ortho X-77 per 100 gallons.

  • Figure 3.
    Figure 3.

    On waxy leaves: (a) spray without spreader does not deposit satisfactorily; (b) high spreader rates ‘slide’ deposits to the ground or into depressions; (c) proper spreader-sticker gives good spray coverage.

  • Figure 4.
    Figure 4.

    anzate® 200 spray residue held by NuFilm-17® on seed corn leaf a full month after application. Blight control was excellent, despite the few lesions showing in this September photograph.

  • Figure 5.
    Figure 5.

    Physical compatibility: In a good smooth spray mixture (a) the individual particles of pesticide are not distinguishable while an incompatible or flocculated mixture (b & c) usually shows a visible separation though it may be more subtle than shown here.

  • Figure 6.
    Figure 6.

    Drift control agents reduce the breakup of sprays into fine droplets that can drift on the wind and increase the range of air blast sprayers and hydraulic hand gun sprayers.

Tables

  • Table 1.

    Alkaline Hydrolysis. Effect of high pH spray solutions on some commonly used pesticides

    ChemicalCommon nameComments
    Dyrene®AnilazineSubject to hydrolysis
    Difolitan®CaptafolDecomposes rapidly above 9.0.
    Furadan®CarbofuranUnstable under alkaline conditions.
    Dylox®TrichlorfonDegrades rapidly (approx. 99% of applied degraded in 2 hrs) in alkaline pond water (pH 8.5) at room temperature.
    Proxol®”
    Dipterex”
    Counter®TerbufosSubject to hydrolysis under alkaline conditions.
    Systox®DemetonSubject to hydrolysis under alkaline conditions.
    Cygon®DimethoatepH 6.0 ½ life = 12 hours. Unstable in alkaline water.
    Diazinon®DiazinonpH 6.0 ½ life = 37 hours. Hydrolysis rapid in strong acid or alkaline water.
    Imidan®PhosmetpH 8.0 ½ life = 4 hours
    pH 7.0 ½ life = 12 hours
    pH 4.5 ½ life = 13 days
    Captan®CaptanpH 10.0 ½ life = greater than 2 minutes
    pH 4.0 ½ life = 4 hours
    Malathion®MalathionStable at pH 5.0-7.0 but rapid hydrolysis in more acidic or alkaline solutions
    Polyram®PolyramUnstable under strongly acidic or alkaline conditions

    • The truth about a couple of fungicides commonly maligned about alkaline hydrolysis.

      BENLATE® or TERSAN® 1991. Benomyl is systematically fungicidal and quite stable in mildly acid to slightly alkaline water solutions. The first breakdown of benomyl is MBC (Methyl 2-benzimidazole carbamate) which is essentially as effective fungicidally. fungicidally.

      BRAVO® . pH 7.0 or lower: no hydrolysis in aqueous solutions. pH 9.0: Rate of decline 1.8% per day (half life = 38.1 days).

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Spray Adjuvants Are Management Tools
T.E. “Ted” Whitmore
Arboriculture & Urban Forestry (AUF) Mar 1986, 12 (3) 57-65; DOI: 10.48044/jauf.1986.013
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