SEDL / STP / STP1400-EB / STP10440S

Optimum Surfactant HLB Value for Nicosulfuron Is Salt Dependent

Nalewaja, JD
Professor, North Dakota State University, Fargo, ND

Matysiak, R
Visiting Scientists, Agricultural University, Poznan,

Woznica, Z
Visiting Scientists, Agricultural University, Poznan,

Pages: 10    Published: Jan 2001

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Abstract

Experiments were conducted to determine nicosulfuron {2-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide} phytotoxicity to large crabgrass (Digitaria sanguinalis L.) as influenced by surfactant HLB, spray volume, pH, and carrier solution salts. Nicosulfuron phytotoxicity to crabgrass was greater when applied in 240 than 80 L/ha in a pH 4 spray carrier, regardless of surfactant. However at pH 9, 80 L/ha spray volume also was effective when most surfactants had a HLB value between 12 and 17. Surfactant chemistry determined the effect of sodium bicarbonate and ammonium nitrate on nicosulfuron efficacy. The optimum HLB for a surfactant with nicosulfuron was lowered when the spray carriercontained ammonium nitrate. Ammonium nitrate enhanced or reduced nicosulfuron phytotoxicity depending on the HLB and chemistry of the accompanying surfactant. Sodium bicarbonate antagonized nicosulfuron phytotoxicity more when applied with low (12 to 13) than high (16 to 17) HLB surfactants. The data demonstrate that the most efficacious surfactant for nicosulfuron depends upon spray volume, pH, and carrier salt.