Deposition and behavior of simazine and pendimethalin treated on the leaves of Manilagrass (
Zoysia matrella) was studied in 1990. In the test in early April, simazine and pendimethalin were applied 2 kg/ha (as a.i.) to the dormant turf field, and in late October, these herbicides were applied with the same dosage to the growing turf field mowed at 25 mm or 50 mm height, respectively.
The amounts of the herbicides deposited on the turf leaves were influenced by the formulation type, spray volume, SAA addition, and the plant height. The initial amounts of both herbicides detected from the leaves after treatment were high when the herbicides applied with low volume spray of wettable powders, and added SAA to the water solution. In addition, the both herbicides, deposited higher concentration on the leaves mowed at 50 mm height than at 25 mm. During the experiments, simazine detected from the leaves remained in higher concentration levels, while pendimethalin decreased rather rapidly.
The behavior of simazine and pendimethalin retained in the turf leaves was studied by the pot test in a green house in 1991. Simazine and pendimethalin were applied 2 kg/ha (as a.i.) to the dormant turfgrass in early April and to the growing turfgrass in mid May. Simazine residue in the leaves decreased a little during the test period. Artificial rainfall applied at an earlier stage slightly promoted run-off of the simazine from leaf surface to the soil.
Pendimethalin residue decreased gradually provably due to the herbicide run-off from leaves to the soil by rainfall and also to the volatilization from the leaf surface.
With the both herbicides, the amounts runoff from the leaves to the soil were greater in the early-April treatment than in the midMay treatment.
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