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Persistence of imazamethabenz‐methyl in soils after autumn and spring applications to wheat
Author(s) -
JENSEN K. I. N.,
GAUL S. O.,
KIMBALL E. R.,
SPECHT E. G.
Publication year - 1997
Publication title -
weed research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 74
eISSN - 1365-3180
pISSN - 0043-1737
DOI - 10.1046/j.1365-3180.1997.d01-59.x
Subject(s) - soil water , loam , agronomy , leaching (pedology) , precipitation , chemistry , persistence (discontinuity) , environmental science , biology , soil science , physics , geotechnical engineering , meteorology , engineering
Summary Imazathabenz‐methyl dissipated rapidly in sandy and sandy loam field soils in Nova Scotia. Canada, seeded to wheat ( Triticum aestivam L.).The time to 50% loss of herbicide residues in the 0‐10 cm soil zone was about 3‐4 weeks after October applications and about 2.5 weeks after June ones. After October applications, there was further loss of >60% of the remaining parent herbicide during the winter and early spring despite periods of prolonged snow cover and freezing, or near freezing, soil temperatures. After October applications, imazamethabenz‐methyl residues in May‐collected samples from the 10‐20 and 20‐30 cm soil zones ranged from 40% to 80% and from 15% to 40%, respectively of those extracted from the 0‐10 cm zone over four sites. Precipitation in the month after October applications ranged from 105 to 180 mm. which suggests leaching may play an important role in dissipation at times of the year when precipitation greatly exceeds evapotranspiration. Levels of the phytoioxic free acid ranged from 15% to 35% of the parent herbicide in selected samples. These residues had no effect on spring wheat replacement crops. The effect of the herbicide on replacement crops may also be influenced by the soil pH. A laboratory study demonstrated that as soil pH increased from 4.1 to 6.5. degradation of imazamethabenz‐methyl increased with a corresponding increase in free acid formation.