Field mint is widespread on Prince Edward Island and has become a problem in the production of cereal grains, potatoes, and other crops. Studies were conducted to determine if deep burial of the rhizome could be used as a control method. Rhizome pieces measuring 2.5, 5.0, or 10.0 cm in length were hand-buried in soil at depths of 2.5, 5.0, 10.0, or 20.0 cm in the spring. As planting depth increased, shoot emergence was delayed and fewer shoots emerged throughout the season. The smallest rhizome of 2.5 cm produced the fewest shoots during the season, but larger rhizomes (5.0 or 10.0 cm long) produced greater amounts of shoot and rhizome dry weights than smaller rhizomes. Deep burial of field mint to 20.0 cm by inversion plowing could be used as a means of field mint control, especially in early planted competitive crops that close canopy quickly.

In greenhouse and field studies, fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy] propanoic acid} controlled quackgrass [Agropyron repens (Beauv.) # AGRRE] in potato (Solanum tuberosum L. ‘Russet Burbank’). Quackgrass control with fluazifop at 0.25 and 0.5 kg ai/ha in the greenhouse was greatest with application at the two-leaf stage compared with the four-and six-leaf stages. Control was not affected by rhizome length, with similar control obtained of plants grown from 2- and 10-node rhizome pieces. Removal of quackgrass shoots at 6 or 24 h after treatment resulted in decreased control at application rates of 0.25 and 0.5 kg/ha. Fluazifop at 0.5 kg/ha controlled quackgrass treated at the four-leaf stage. The active enantiomer of fluazifop at half the rate of the racemic mixture controlled the quackgrass to the same extent. Fluazifop did not affect potato yield.

Reduction of initial top growth of quackgrass with haloxyfop at 0.13 kg ai ha-1 and above in the greenhouse was comparable at the 2-, 4-, and 6-leaf stages. Quackgrass control was not affected by rhizome length in plants grown from 2-node and 10-node rhizome pieces. Removal of quackgrass shoots 6 h after treatment resulted in increased initial topgrowth, regrowth, and rhizome weight at all application rates when compared to treatments with no removal of shoots; however, growth decreased with increasing rates of haloxyfop. Later removal at 24 or 96 h after treatment did not affect quackgrass control, indicating rapid translocation. In field-grown potato, haloxyfop applied at 0.25 kg ha-1 at the 4- to 5-leaf stage controlled more than 80% of quackgrass. Lower rates controlled less than 80% when used alone; but adding cultivation improved control. No adverse effect on potato yield was noted with haloxyfop.