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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research » Research » Research Project #435470

Research Project: Efficacy and Crop Safety of Herbicide-Treated Mulch for Liner Production of Woody Ornamental Plants

Location: Horticultural Crops Research

Project Number: 2072-22000-043-31-G
Project Type: Grant

Start Date: Sep 1, 2018
End Date: Aug 31, 2019

To evaluate the potential safening effect of treating mulches with herbicides prior to adding to the top of liners containing woody ornamental plants.

The maximum labeled rates of flumioxazin, oxyfluorfen, isoxaben, and two-way mixes of these three products will be applied to two kinds of mulch (cedar bark and rice hulls). This will result in six treatments for each of the two mulch types (12 separate treatments), plus three check pots (non-mulched, mulched with nontreated cedar bark, and mulched with nontreated rice hulls) for 15 treatments in the trial. Woody plant species will be determined based on availability, but three species are envisioned to be tested (15 treatments x 3 replicates = 45 plants for each of the three species, 135 total plants). Plant material will be transplanted into appropriate-sized pots for the plant species to be tested, each filled with standard potting soil. An adequate volume of cedar bark and rice hulls will be spread on sheets and treated with the herbicides noted earlier, and allowed to dry for 24-hours prior to application to pots. Pots will be maintained outside, and visual weed control and injury percentages will be estimated periodically during the growing season. The plants will then be destructively harvested and above- and below-ground biomass measured, and observed for abnormalities in growth (crooked stems, swellings at the soil line, etc.). The experimental design for the trial will be a completely random design with three replicates for each of the three species.