Persistence and Leaching of Herbicides in Oxisol and Their Efficiency in Suppressing Weed Emergence Flow

Aims: The aim of this study was to evaluate the residual effect of herbicides on the flow of emerging plants over time, at different depths of soil in an area of cane sugar over a oxisol.

Study Design: In the field, the design was a randomized block with six treatments and four replications. In the greenhouse, the completely randomized design while maintaining the same treatment in the field, In both steps, we used the following herbicides, sulfentrazone, amicarbazone, tebuthiurom, diuron + hexazone, imazapic and control treatment.

Place and Duration of Study: The field experiment was carried out at Sugarcane Center in Ribeirão Preto, São Paulo State, Brazil (21°12’00.4”S, 47°52’21.7”W) during the rainy season (setember to march).

Methodology: To assess the leaching were used PVC pipe of 10 cm in diameter, longitudinally sectioned, were buried to a depth of 20 cm attempting to maintain the original structure of soil. After fixing the pipes in the ground, were sown seeds of ivy-leaf morning glory (Ipomoea hederifolia) between cane rows, in order to verify the effectiveness of herbicides in controlling this plant daninha. After 90 days, the tubes were removed, separated into halves and placed in greenhouse, where seeds of the test plants rope-glory (Ipomoea hederefolia) lengthwise along the profile of each half of the tubes. At 30 days after sowing, the number of plants was recorded at depths 0-5, 5-10, 10-15 and 15-20 cm.

Results: The herbicides sulfentrazone and amicarbazone obtained greater control of Ipomoea hederifoliaemergency flow over other treatments. For 0-5 cm deep layer of the herbicides studied showed leaching. The herbicide sulfentrazone showed higher leaching compared to other herbicides in the 0-5 and 5-10 cm deep. Tebuthiuron controlled germination of Ipomoea hederifolia at depths greater than 10cm,

Conclusion: The suppressive effect on emergency flow of weeds was observed only superficially.