Treflan / trifluralin

WSSA Resistance Group: 3

Crop/non-crop registration: Soybeans, beans, canola, direct-seeded alfalfa, transplants of tomatoes, peppers, cole crops, carrots, strawberries

Sensitive weeds: Annual grasses; will provide good control of pigweed and lambsquarters including triazine-resistant biotypes.

Application method: PPI - incorporate to 8-10 cm (3"-4"); should be incorporated within 24 hrs to avoid volatilization and photodegradation losses, especially on moist soils.

Absorption & Translocation: Readily absorbed by young roots and shoots but no significant translocation;susceptible weeds are controlled as they germinate (affects shoots: grass coleoptile, BLW (broadleaf weeds): hypocotyl/epicotyl). Established weeds are not controlled.

Mode of Action: Disruption of mitosis (inhibitor of microtubule synthesis).

Metabolic pathway inhibited: Binds to tubulin, the major microtubule protein; leads to microtubule loss and absence of spindle apparatus. This prevents the alignment and separation of chromosomes during mitosis. Dinitroaniline-induced microtubule loss typically results in the swelling of root tips as cells in this region fail to divide or elongate.

Basis of Selectivity: Physiological growth processes associated with seed germination.

Symptoms: Inhibits root and shoot growth; initial effects observed on roots, especially the development of lateral or secondary roots; leads to thickened and stubby primary roots, especially tips. Inhibition of shoot growth is a secondary effect caused by limited root growth. Most weeds affected do not emerge from soil, but if they do, typically have one or two leaves.

Residuality: Intermediate (1-4 months); recommended rates provide season long control.

Toxicity: Oral LD50 >5000 mg/kg - practically non-toxic.

Additional comments: Strongly adsorbed to soil particles with negligible leaching; soil organic matter and clay content thus affect application rates; activated upon incorporation; rainfall is not required.

Images above: Trifluralin (PPI) damage to corn roots. Note: the thickened and stubby primary root, especially the root tip and absence of lateral roots (left). Trifluralin (PPI) damage to corn shoots (right).

Images above: Trifluralin (PPI) damage to winter wheat shoots (left). Trifluralin (PPI) on broadleaf and grass crops and weeds. Note: healthy appearance of soybean and seedling alfalfa in the front flat and tomatoes in the second flat (right).