Treat multiflora rose in May and June

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BUTLER, Pa. - Multiflora rose is a problem in pastures for many area farmers. It thrives on idle land, fence rows, and hilly pastures.

Originally introduced from Asia and promoted as a “living fence” to control erosion and provide food and cover for wildlife, multiflora rose quickly spread and is now considered a noxious weed in nearby states.

Its aggressive growth can rapidly overtake desirable land, forming a dense, thorny thicket within a few years.

Although the weed spreads mainly through seed dispersal by birds and other animals, it also spreads by layering. Layering occurs when the tip of the cane, or woody stem, touches the ground, forms a shallow root system, and generates a new shoot.

Mature shrubs can grow 9-12 feet wide and 6-10 feet tall, producing many arching, thorny canes.

Now’s the time. According to Ryan Hockensmith, Extension Agronomy Agent for Beaver, Butler, and Lawrence counties, late May through early June has proven to be the ideal time to apply herbicides for the control of multiflora rose.

Local studies have shown that the opportune time to successfully kill the weed is when it reaches the bud to bloom stage.

Hockensmith suggests three foliar applied herbicides for control during this period. The herbicides are Ally, Crossbow, and glyphosate (Roundup). All three should be applied to uniformly wet the entire foliage.

Ally is used at a rate of 1 ounce per 100 gallons of water plus a surfactant. Ally does not carry a grazing restriction but will limit crop rotation. It is also safe on established grasses.

“Ally may take up to 3 weeks to exhibit symptoms, so don’t be discouraged,” Hockensmith said.

Herbicide. Crossbow can be used at a rate of 4 to 6 ounces per 3 gallons of water. It does carry a 14-day grazing restriction for dairy cattle if 2 gallons per acre or less is used. It is also safe on grasses.

Glyphosate use rates vary with the concentration of the product, so consult the label.

In local studies, glyphosate has provided more variable control in late spring than the other two products, but shines as we get into late summer and early fall. A 14-day interval is required for grazing animals.

Good news. “The news isn’t all bad on the multiflora rose front,” said Hockensmith, who reports seeing more evidence of the Rose Rosette disease throughout western Pennsylvania.

While this virus probably won’t eradicate this pest, it should reduce it over the long run, he said.

Plants contracting the virus will usually die. Watch for weak looking plants that produce many reddish colored shoots towards the end of their canes.

For more information on multiflora rose, request a copy of Agronomy Facts 46: Multiflora Rose Management in Grass Pastures by calling the Butler County Extension office at 724-287-4761.

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