Rice fields treated with Penoxsulam herbicide show good safety

Penoxsulam is a sulfonylurea herbicide. The drug is absorbed through weed leaves, stems and roots, and is translocated via the xylem and phloem to the meristematic zones where it acts. When used in rice fields, Penoxsulam provides both foliar treatment and soil residual (pre-emergence) control effects.

After Penoxsulam treatment, weeds quickly stop growing; 2-4 days after application the growing points fade, and sometimes the leaf veins turn red; 7-14 days after application the stem tips and leaf buds begin to wither and necrose; 2-4 weeks after application the weeds die. The speed of weed death is related to the accumulation of branched-chain amino acids in the plant. Young weeds have small reserves of branched-chain amino acids and die relatively quickly; larger plants and older weeds die slowly, and unfavorable environmental conditions will slow down the speed at which the herbicide takes effect.

The active ingredient in Penoxsulam degrades rapidly within rice plants, making it safe for rice from the 1-leaf stage through to before harvest. Some research reports indicate that when Penoxsulam is applied as a soil residual (pre-emergence) treatment after direct-seeded rice sowing, it also provides good control of weeds and is safe for rice.