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 herbicide S -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.
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Claims 4
Claim · model-written summary
Phytotoxicity of the weak acid and weak base herbicides (dicamba, 2,4-D, prometone, amitrole) increased as soil pH rose, with a maximum at pH 6.5
Not reportedTaxon
Verbatim
e1“Phytotoxicity increased as the soil pH increased and reached a maximum at pH 6.5”
Claim · model-written summary
Phytotoxicity of dalapon, diquat, paraquat and vernolate increased as soil pH fell, with a maximum at pH 4.3
Not reportedTaxon
Verbatim
e2“Conversely, phytotoxicity increased as soil pH decreased and reached a maximum at pH 4.3”
Claim · model-written summary
Soil pH between 4.3 and 7.5 had no effect on the phytotoxicity of chloramben, picloram, dichlobenil, isocil, diuron and nitralin
Not reportedTaxon
Verbatim
e3“Soil pH levels between 4.3 and 7.5 had no effect on the phytotoxicity”
Claim · model-written summary
A one-unit change in soil pH decreased the phytotoxicity of seven herbicides by a factor of two to four
- Treatment
- A change of one pH unite4
- Outcome
- phytotoxicitye4
- Direction
- decreasede4
- Value
- a factor of two to foure4
Not reportedTaxon
Verbatim
e4“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”