Experimental Approaches to Reed Canarygrass Control

Experimental Approaches to Reed Canarygrass Control

Plant Growth Regulators

Plant growth regulators (PGRs) are synthetic plant hormones used commercially in a variety of agricultural applications. PGRs that promote active growth in dormant tissues may make reed canarygrass rhizomes more susceptible to herbicide treatments. At least eleven different PGR chemicals have potential for this purpose. Of these, X-Cyte® (kinetin, a synthetic cytokinin) and 2:1 mixtures of Cycocel® (chlormequat chloride, a gibberellic acid synthesis inhibitor) and Proxy® (ethephon, an aqueous form of ethylene) are currently under experimental investigation. PGR applications may also have potential for inhibiting panicle development in reed canarygrass. If the PGR approach is feasible and cost-effective, it will be a few years before treatment protocols can be established for their use.

Short-Term Split Applications

Split applications are also designed to elicit greater rhizome mortality with herbicides. A split application is a pair of half-dose herbicide treatments applied on two separate dates, typically 1 – 2 weeks apart. In theory, the first application weakens rhizome apical dominance and the follow up application kills more of the rhizome. Results, however, have been mixed. In general, this approach works well in greenhouse and mesocosm studies, but is less effective in field populations. A major problem with this approach is that the initial application induces necrosis in the leaves, which inhibits absorption and transport of the herbicide during the follow up application.

Reverse Fertilization

Nitrogen availability in the soil can give reed canarygrass an even greater competitive advantage because of its early growth relative to other native wetland species. Reverse fertilization is a way to temporarily remove excess nitrogen from the soil. In this approach, a source of carbon (such as sugar or sawdust) is added to the soil to promote microbial growth. Microbial growth then ties up soil nitrogen so it isn’t available to reed canarygrass. Preliminary results from this approach have been mixed.

Boric Acid Application

Boric acid fertilizer can be used as a nonselective biodegradable herbicide. Foliar applications of 300-ppm boric acid aqueous solution to reed canarygrass has been shown to cause complete foliage dieback within three weeks. This approach has been tested for control of reed canarygrass along roadsides and ditchbanks but has not been attempted in natural areas.