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A WEED REPORT from the book Weed Control in Natural Areas in the Western United States Perennial pepperweed <br /> helpful for removing accumulated thatch.Mowing breaks old stems into small fragments and helps prevent <br /> shading of favorable species.Combining mowing with herbicides has been shown to be an effective control <br /> strategy.For best results,mow plants at the bolting or flower bud stage and apply herbicides to <br /> resprouting shoots once they have reached the flower bud stage. <br /> Cultural Cattle,sheep,and goats will graze perennial pepperweed,especially rosettes in early spring.When stands <br /> are dense it becomes difficult for most animals to graze.Goats appear to tolerate heavy consumption of <br /> fresh plants.Sheep and goats permanently maintained in a pasture suppress growth of perennial <br /> pepperweed.However,once livestock are removed,plants quickly resprout. <br /> Burning is not effective at reducing perennial pepperweed stands,but it is helpful at removing accumulated <br /> thatch.Perennial pepperweed thatch burns best in winter or spring under dry conditions before initiation <br /> of spring growth. <br /> Seasonal flooding for an extended period during the growing season can significantly reduce populations.It <br /> is not known how long perennial roots can survive flooded conditions,but anecdotal information indicates <br /> that 6 months of submergence are required. <br /> Establishing desirable vegetation in disturbed areas can suppress perennial pepperweed and slow <br /> reinvasion after control.Because perennial pepperweed is very competitive,seed or transplant desirable <br /> vegetation after dense perennial pepperweed stands are controlled.Choose vigorous,fast-growing plant <br /> species that are adapted to the site.Perennial grasses are a good choice for natural areas and pastures. <br /> Grasses are tolerant of broadleaf-selective herbicides,and overtime grasses form a thick sod that prevents <br /> future weed establishment.in pastures,promote grass expansion and vigor with fertilization and grazing <br /> management. <br /> Biological Biological control agents are being evaluated for use on perennial pepperweed in the United States,but <br /> currently no organisms are available. <br /> CHEMICAL CONTROL <br /> The following specific use information is based on reports by researchers and land managers.Other trade <br /> names may be available,and other compounds also are labeled for this weed.Directions for use may vary <br /> between brands;see label before use.Herbicides are listed by mode of action and then alphabetically.The <br /> order of herbicide listing is not reflective of the order of efficacy or preference. <br /> GROWTH REGULATORS <br /> 2,4-D Rate:2 qt product/acre(1.9 lb a.e./acre) <br /> Several names Timing:Postemergence at rosette to flowering stages.Most effective at flower bud or flowering stage. <br /> Remarks:2,4-D often requires annual application for multiple years.It is broadleaf-selective and safe <br /> on most grasses.2,4-D has minimal soil activity.Do not apply ester formulations when outside <br /> temperatures exceed 80°F.Amine forms are as effective as ester forms,and amine forms reduce the <br /> chance of off-target movement. <br /> AROMATIC AMINO ACID INHIBITORS <br /> Glyphosate Rate:2 to 4 qt product(Roundup Pro Max)/acre(2.25 to 4.5 lb a.e./acre).Spot treatment:2%product <br /> Roundup,Accord XRT v/v <br /> Il,and others Timing:Postemergence from seedling to bloom stage.Most effective at flower bud or flowering stage. <br /> Remarks:Glyphosate will not kill seeds or inhibit germination the following season.Glyphosate is <br /> nonselective and has no soil activity.It can create bare ground conditions that are susceptible to weed <br /> recruitment.In areas with desirable vegetation,use spot treatment.Glyphosate is a good control <br /> option if reseeding is planned shortly after application,as it will not injure seedlings emerging after <br /> application.Add a surfactant when using a formulation where it is not already included(e.g.,Rodeo, <br /> Aquamaster). <br /> BRANCHED-CHAIN AMINO ACID INHIBITORS <br /> Chlorsulfuron Rate:1 to 2.6 oz product/acre(0.75 to 1.95 oz a.i./acre) <br /> Telar Timing:Postemergence from seedling to flowering stage.Most effective at flower bud or flowering <br /> stage. <br /> Remarks:Chlorsulfuron has long soil residual activity.It has mixed selectivity,but is generally safe on <br /> grasses.Always use a surfactant.2,4-D at 1 to 2 pt/acre can be tank-mixed with chlorsulfuron for <br /> 2 of 3 2013 <br />