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.
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).