Formulation affecting alachlor efficacy and persistence in sandy soils.
BACKGROUND
The development of controlled-release formulations of alachlor to extend the period of weed control was studied. This extended duration reduces the need for high herbicide application rates that could lead to environmental contamination. For this purpose, the influence of formulation, as well as the influence of soil characteristics, on alachlor efficacy and persistence in soil of a commercial formulation (CF) and different ethylcellulose microencapsulated formulations (MEFs) was evaluated.


RESULTS
Higher alachlor rates yielded an enhanced initial herbicidal activity. The prolonged release of alachlor provided by the MEFs resulted in a higher herbicidal efficacy and a longer period of weed control compared with the effects of CF in the two soils tested (at 40 days after treatment, oat growth inhibition for CF and MEFs was 1.96% and 93.5% respectively). Soil characteristics strongly influenced alachlor efficacy and weed control by MEFs. The highest alachlor efficacy and persistence were observed in the soil with lowest microbial activity and clay and organic matter content.


CONCLUSIONS
The use of MEFs can be advantageous because they permit the maintenance of the desired concentration of the herbicide in the soil for longer periods of weed control.
Institute of Natural Resources and Agrobiology (CSIC), Apdo 1052, 41080 Seville, Spain. fsopenav@irnase.csic.es
Fátima
F
Sopeña
Celia
C
Maqueda
Esmeralda
E
Morillo
D000081:Acetamides / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical; D004339:Drug Compounding / Q000379:methods*; D004355:Drug Stability; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D012987:Soil / Q000032:analysis*
D000081:Acetamides; D006540:Herbicides; D012987:Soil; C000188:alachlor