Susceptibility of Pea Cultivars to Trifluralin

The relative susceptibility of ‘Alaska’ and ‘Perfection’ cultivars of peas ( Pisum sativum L.) to trifluralin (α,α,α-trifluoro-2,6-dinitro- N,N -dipropyl- p -toluidine) was studied in excised roots, and in greenhouse and field plantings. Elongation of excised Alaska and Perfection pea roots was reduced 32 and 25%, respectively, by 4 mg/L dosages of trifluralin in aseptic culture, and 25 and 10% by 1.68 kg/ha dosages in greenhouse-grown plants. Seedling emergence in the greenhouse and field was reduced or delayed in both cultivars by 1.68 kg/ha trifluralin. Yields of field-grown Alaska and Perfection peas were reduced by trifluralin dosages equal to and exceeding 0.84 and 1.68 kg/ha, respectively, when there was a June water deficit (8 cm). Yields were not reduced in either cultivar when June rainfall was near normal (10.9 cm).