Prowl / pendimethalin

WSSA Resistance Group: 3 

Crop/non-crop registration: Field and sweet corn, soybean, potatoes, forage legumes, onions

Sensitive weeds: Mostly annual grasses; common chickweed, pigweed, lambsquarters, velvetleaf.

Application method: PRE or (early POST) in corn, potatoes; PPI or PRE in soybeans, forage legumes.

Absorption & Translocation: Readily absorbed by young roots but no significant translocation occurs;susceptible weeds are controlled as they germinate (affects 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: No significant uptake or translocation by tolerant species.

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); persistence depends on weather conditions (greater if dry); only registered crops may be planted in year of application; days to harvest restriction of 100 days.

Toxicity: Oral LD50 >5000 mg/kg - practically non-toxic (PROWL= 4075 mg/kg- slightly toxic).

Additional comments: Strongly adsorbed to soil particles with negligible leaching; soil organic matter and clay content thus affect application rates; most effective when rain received within 7 days of application; do not graze treated areas or feed treated foliage to livestock prior to 100 days following application.