Phytotoxicity of Herbicide Residues In Soils1
- Rodney J. Fink2
Injury to rotational crops by herbicide carryover has been experienced with some triazine herbicides. The objective of this study was to compare relative dissipation rates and carryover phytotoxicity of three triazine herbicides. Corn (Zea mays L.) was planted on May 2, 1969, May 2, 1970, and May 19, 1970. Two-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine), 2-chloro-4-(cyclopropylamino)-6-(isopropylamino)-s-triazine (cyprazine), 2-(4-chloro-6-ethylamino-s-triazine-2-ylamino)-2-methylpropionitrile (SD-15418), and 2-chloro-2′,6′-diethyl-N-(methoxymethyl) acetanilide (alachlor) were applied on day of planting. Atrazine plus nonphytotoxic oil and cyprazine were applied postemergence 20 days after planting. Soil samples were collected 6, 12, 18, and 26 weeks after planting. Soybeans [Glycine max (L.) Merr.], alfalfa (Medicago sativa L.), and oats (Avena sativa L.), were planted in the soil and placed in a growth chamber. Dry matter yields of alfalfa, oats, and soybeans showed that alachlor had the least soil residual followed by SD-15418, atrazine, and S-6115. Soybeans were the most tolerant of the three species to triazine residues in soils.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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