Herbicide absorption and translocation patterns were determined following a wet blade method of application to dogfennel stems. Treatment consisted of severing stems with a pruning shear blade containing 5 μl of [14C]-triclopyr or [14C]-clopyralid solution. More than 73 or 82% of applied [14C]-triclopyr or [14C]-clopyralid was absorbed immediately, and uptake increased to more than 90%, 60 min after treatment. Both radiolabeled compounds appeared in the roots as soon as 12 h after treatment. By 48 h, 5 to 7% of the [14C] label was present in the roots, and 7 to 10% was exuded from the roots.

Laboratory studies were conducted to determine the effect of various factors on germination of dogfennel and yankeeweed. Dogfennel seed were found to be strongly photoblastic with no germination in the dark. Yankeeweed seed were moderately photoblastic, with 12% germination occurring in the absence of light Germination for both species increased in response to red light (650 nm), indicating phytochrome regulation. At the soil surface, dogfennel and yankeeweed emergence was 40 and 48%, respectively, but declined rapidly with increasing soil depths where dogfennel germination was lower than that of yankeeweed. Yankeeweed germination was 60 to 75% from 10 to 30 C while dogfennel germination was 45 to 70% between 15 to 30 C. Both species germinated over a broad range of pH (6 to 10) with the highest germination occurring at pH 8. Yankeeweed and dogfennel were moderately tolerant to water stress, but yankeeweed tolerated higher water stress than dogfennel. Both species germinated over a wide range of conditions, possibly enhancing adaptation to many diverse environments.

Greenhouse and field studies were conducted to investigate the responses of container-grown dogfennel, multiflora rose, and purple loosestrife to clopyralid or triclopyr applied to plants from a pruning shear blade. Clopyralid or triclopyr was diluted with water to various concentrations and placed on one side of a pruning shear blade in final volumes of either 1 or 5 μl. The shears were then used to sever and treat stems. Results indicated that 20% triclopyr concentrations in 5-μl total volume (360 μg active) gave ≥ 96% reductions of foliar regrowth in dogfennel, multiflora rose, and purple loosestrife 70, 42, and 56 days after treatment (DAT), respectively. The same delivery rate for clopyralid gave 96% dogfennel control 70 DAT. Subsequent visual ratings with multiflora rose (105 DAT) and purple loosestrife (260 DAT) confirmed that early reductions in biomass were good indicators of long-term control.