Environmental fate of the insecticide cypermethrin applied as microgranular and emulsifiable concentrate formulations in sunflower cultivated field plots.

A field dissipation and transport study of the insecticide cypermethrin applied as microgranular (MG) and emulsifiable concentrate (EC) formulations has been conducted in field sunflower cultivations and bare soil plots with two different slopes (1% and 5%). The dissipation of insecticide in soil (on planting rows) was monitored for a period of 193 days. Cypermethrin residual concentrations in the upper soil layer (0-10 cm), 2 days after soil application (DASA), ranged from 0.53 to 0.73 µg g(- 1) when the maximum values were observed 7 DASA, ranged from 1.06 to 1.23 µg g(-1). The dissipation rate was better described by first-order kinetics. The average half-life in cultivated (tilled and planted) plots was 23.07 and 24.24 days for soil slopes 5% and 1%, respectively. In uncultivated (tilled but not planted) plots the respective values were 22.01 and 22.37 days. The insecticide was found below the 10 cm soil layer occasionally in few samples at low concentrations (< 0.02 µg g(- 1)). In runoff water it was detected once (7 days after foliar application, at levels below LOQ), when in sediment it was detectable for seven samplings. The maximum values were observed 7 days after foliar application, when they reached 0.097 and 0.143 µg g(-1) in cultivated plots with soil slopes 1% and 5%; and 0.394 and 0.500 µg g(-1) in uncultivated plots, respectively. The amount of cypermethrin which was transferred by the sediment remained at low levels (less than 0.01% of the totally applied active ingredient), even in plots with 5% inclination. The insecticide was detected in leaves and stems of the sunflower plants after the foliar application up to the day of harvest. On the contrary, in roots it was detectable during the whole cultivation period. No residues were detected in flowers or seeds.

Persistence of oxyfluorfen in soil, runoff water, sediment and plants of a sunflower cultivation.

A field dissipation and transport study of oxyfluorfen in a sunflower cultivation under Mediterranean conditions have been conducted in silty clay plots (cultivated and uncultivated) with two surface slopes (1% and 5%). The soil dissipation and transport of oxyfluorfen in runoff water and sediment, as well as the uptake by sunflower plants, were investigated over a period of 191 days. Among different kinetic models assayed, soil dissipation rate of oxyfluorfen was better described by first-order kinetics. The average half-life was 45 and 45.5 days in cultivated plots with soil slopes 5% and 1% respectively, and 50.9 and 52.9 days in uncultivated plots with soil slopes 5% and 1%. The herbicide was detected below the 10 cm soil layer 45 days after application (DAA). Limited amounts of oxyfluorfen were moved with runoff water and the cumulative losses from tilled and untilled plots with slope 5% were estimated at 0.007% and 0.005% of the initial applied active ingredient, while for the plots with slope of 1%, the respective values were 0.002% and 0.001%. The maximum concentration of oxyfluorfen in sediment ranged from 1.46 µg g(-1) in cultivated plot with soil slope 1% to 2.33 µg g(-1) in uncultivated plot with soil slope 5%. The cumulative losses from tilled and untilled plots with slope 5% were estimated at 0.217% and 0.170% while for the plots with slope of 1%, the respective values were 0.055% and 0.025%. Oxyfluorfen was detected in sunflower plants until the day of harvest; maximum concentrations in stems and leaves (0.042 µg g(-1)) were observed 33 DAA and in roots (0.025 µg g(-1)) 36 DAA. In conclusion, oxyfluorfen hardly moves into silty clay soil and exhibited low run-off potential so it represents a low risk herbicide for the contamination of ground and adjacent water resources.