Nanoparticles based
on biodegradable polymers have been shown to
be excellent herbicide carriers, improving weed control and protecting
the active ingredient in the crop fields. Metribuzin is often found
in natural waters, which raises environmental concerns. Nanoencapsulation
of this herbicide could be an alternative to reduce its losses to
the environment and improve gains in its efficiency. However, there
is a paucity of information about the behavior of nanoformulations
of herbicides in environmental matrices. In this study, the stability
of nanoencapsulated metribuzin in polymeric nanoparticles (nanoMTZ) was verified over time, as well as its dissipation
in different soils, followed by the effects on soil enzymatic activity.
The physiological parameters and control effects of nanoMTZ on Ipomoea grandifolia plants
were investigated. No differences were verified in the half-life of
nanoencapsulated metribuzin compared to a commercial formulation of
the herbicide. Moreover, no suppressive effects on soil enzymatic
activities were observed. The retention of nanoMTZ
in the tested soils was lower compared to its commercial analogue.
However, the mobility of nanoencapsulated metribuzin was not greatly
increased, reflecting a low risk of groundwater contamination. Weed
control was effective even at the lowest dose of nanoMTZ (48 g a.i. ha–1), which was consistent with
the higher efficiency of nanoMTZ compared to the
conventional herbicide in inhibiting PSII activity and decreasing
pigment levels. Overall, we verified that nanoMTZ
presented a low environmental risk, with increased weed control.