Author:
Corbin F. T.,Upchurch R. P.,Selman F. L.
Abstract
The influence of soil pH (4.3 to 7.5) on the phytotoxicity of herbicides incorporated into high organic soils was studied. Phytotoxicity increased as the soil pH increased and reached a maximum at pH 6.5 for the weak aromatic acids 3,6-dichloro-o-anisic acid (dicamba) and (2,4-dichlorophenoxy)-acetic acid (2,4-D) and the weak bases 2,4-bis(isopropylamino)-6-methoxy-s-triazine (prometone) and 3-amino-s-triazole (amitrole). Conversely, phytotoxicity increased as soil pH decreased and reached a maximum at pH 4.3 for the weak aliphatic acid 2,2-dichloropropionic acid (dalapon), the cationic herbicides 6,7-dihydrodipyrido[1,2-a:2′,1′-c]pyrazinediium ion (diquat) and 1,1′-dimethyl-4,4′-bipyridinium ion (paraquat), and a nonionic herbicideS-propyl dipropylthiocarbamate (vernolate). Soil pH levels between 4.3 and 7.5 had no effect on the phytotoxicity of (a) the weak aromatic acids 3-amino-2,5-dichlorobenzoic acid (chloramben) and 4-amino-3,5,6-trichloropicolinic acid (picloram); and (b) the nonionic herbicides 2,6-dichlorobenzonitrile (dichlobenil), 5-bromo-3-isopropyl-6-methyluracil (isocil), 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron), and 4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline (nitralin). A change of one pH unit decreased the phytotoxicity of 2,4-D, dicamba, dalapon, prometone, amitrole, paraquat, and vernolate by a factor of two to four depending on the particular herbicide and the pH values considered.
Publisher
Cambridge University Press (CUP)
Subject
Plant Science,Agronomy and Crop Science
Cited by
39 articles.
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