African rue (Peganum harmalaL.) is a toxic and highly invasivenonnativ - PDF document

African rue (Peganum harmalaL.) is a toxic and highly invasivenonnative plant that infests much of the western and south-western United States. It is a native of the deserts of Africa andsouthern Asia that was first noticed in the United States nearDeming, New Mexico in 1930. It is now a significant problem inNew Mexico, Arizona, California, Nevada, Idaho, Oregon,Washington and the far western part of Texas (especially Reeves,Loving, Ward, Pecos and Crane Counties).In western Texas, African rue begins growing in late spring, ear-lier than most native warm-season plants. Young plants are Texas Cooperative EXTENSIONThe Texas A&M Universit y S y stem L-542910-02African Rue On rights-of-way and noncropland areasAfrican rue often grows along caliche roadsides and on caliche oilfield pad sites. Soil-applied herbi-cides do not work well in such areas because the soil infiltration rates are extremely slow and thecaliche binds the herbicide (making it less available to the plant roots). On these sites, use Arsenalª,a liquid herbicide diluted in water and applied to the foliage. Table 2 shows both broadcast and indi-vidual plant treatment rates. For best results, treat in the fall when plants are actively growing. Usethis product with caution because it can damage desirable plants. When African rue is growing withdesirable plants, use the individual plant treatment method. HerbicideBroadcast rateIndividual plant (a.i./acre)treatment rateTime to applyRemarks Table 3. Mixing instructions for individual plant treatments with Arsenalª.Ounces of ingredient for various tank sizes IngredientPercent1 gal.4 gals.15 gals.30 gals.55 gals.125 gals.Arsenalª0.50.64 oz.2.6 oz.9.6 oz.19.2 oz.35.2 oz.80.0 oz.Surfactant0.250.32 oz.1.3 oz.4.8 oz.9.6 oz.17.6 oz.40.0 oz.Dye0.250.32 oz.1.3 oz.4.8 oz.9.6 oz.17.6 oz.40.0 oz. Educational programs of Texas Cooperative Extension are open to all people without regard to race, color, sex, disability, reli Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amenJune 30, 1914, in cooperation with the United States Department of Agriculture. Chester P. Fehlis, Director, Texas Cooperative Texas A&M University System. Biology and Management Produced by Agricultural Communications, The Texas A&M University SystemExtension publications can be found on the Web at: http://tcebookstore.org Educational programs of Texas Cooperative Extension are open to all people without regard to race, color, sex, disability, reli Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amenJune 30, 1914, in cooperation with the United States Department of Agriculture. Chester P. Fehlis, Director, Texas Cooperative Texas A&M University System. Biology and Management (a.i./acre)treatment rateTime to applyRemarksArsenalª0.5 pounds0.5%Late SeptemberApply to fall regrowth (2 pints of through Octoberthat is in good growing product)(or to first frost)condition. Use the individual plant treatment method near desirable v������uc ‡g|lÜ‹ @
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stem On rights-of-way and noncropland areasAfrican rue often grows along caliche roadsides and on caliche oilfield pad sites. Soil-applied herbi-cides do not work well in such areas because the soil infiltration rates are extremely slow and thecaliche binds the herbicide (making it less available to the plant roots). On these sites, use Arsenalª,a liquid herbicide diluted in water and applied to the foliage. Table 2 shows both broadcast and indi-vidual plant treatment rates. For best results, treat in the fall when plants are actively growing. Usethis product with caution because it can damage desirable plants. When African rue is growing withdesirable plants, use the individual plant treatment method.For broadcast treatments, combine the recommended rate of Arsenalª (2 pints) with 0.25 percentnonionic surfactant in water. Use ground application equipment to deliver 10 to 25 gallons per acreof total spray volume. For individual plant treatments, use 0.5 percent Arsenalª with 0.25 percent nonionic surfactant inwater. Mix thoroughly. Add a blue dye to identify treated plants. Table 3 gives mixing instructions forvarious tank sizes. Spray each plant thoroughly to the point of glistening, but not to the point ofrunoff. Table 2. Recommendations for controlling African rue on rights-of-way and HerbicideBroadcast rateIndividual plant (a.i./acre)treatment rateTime to applyRemarksArsenalª0.5 pounds0.5%Late SeptemberApply to fall regrowth (2 pints of through Octoberthat is in good growing product)(or to first frost)condition. Use the individual plant treatment method near desirable vegetation. Table 3. Mixing instructions for individual plant treatments with Arsenalª.Ounces of ingredient for various tank sizes IngredientPercent1 gal.4 gals.15 gals.30 gals.55 gals.125 gals.Arsenalª0.50.64 oz.2.6 oz.9.6 oz.19.2 oz.35.2 oz.80.0 oz.Surfactant0.250.32 oz.1.3 oz.4.8 oz.9.6 oz.17.6 oz.40.0 oz.Dye0.250.32 oz.1.3 oz.4.8 oz.9.6 oz.17.6 oz.40.0 oz. Produced by Agricultural Communications, The Texas A&M University SystemExtension publications can be found on the Web at: http://tcebookstore.org Educational programs of Texas Cooperative Extension are open to all people without regard to race, color, sex, disability, reli Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amenJune 30, 1914, in cooperation with the United States Department of Agriculture. Chester P. Fehlis, Director, Texas Cooperative Texas A&M University System. Biology and Management (a.i./acre)treatment rateTime to applyRemarksArsenalª0.5 pounds0.5%Late SeptemberApply to fall regrowth (2 pints of through Octoberthat is in good growing product)(or to first frost)condition. Use the individual plant treatment method near desirable African rue (Peganum harmalaL.) is a toxic and highly invasivenonnative plant that infests much of the western and south-western United States. It is a native of the deserts of Africa andsouthern Asia that was first noticed in the United States nearDeming, New Mexico in 1930. It is now a significant problem inNew Mexico, Arizona, California, Nevada, Idaho, Oregon,Washington and the far western part of Texas (especially Reeves,Loving, Ward, Pecos and Crane Counties).In western Texas, African rue begins growing in late spring, ear-lier than most native warm-season plants. Young plants are Texas Cooperative EXTENSIONThe Texas A&M Universit y S y stem L-542910-02African Rue On rights-of-way and noncropland areasAfrican rue often grows along caliche roadsides and on caliche oilfield pad sites. Soil-applied herbi-cides do not work well in such areas because the soil infiltration rates are extremely slow and thecaliche binds the herbicide (making it less available to the plant roots). On these sites, use Arsenalª,a liquid herbicide diluted in water and applied to the foliage. Table 2 shows both broadcast and indi-vidual plant treatment rates. For best results, treat in the fall when plants are actively growing. Usethis product with caution because it can damage desirable plants. When African rue is growing withdesirable plants, use the individual plant treatment method. HerbicideBroadcast rateIndividual plant (a.i./acre)treatment rateTime to applyRemarks Table 3. Mixing instructions for individual plant treatments with Arsenalª.Ounces of ingredient for various tank sizes IngredientPercent1 gal.4 gals.15 gals.30 gals.55 gals.125 gals.Arsenalª0.50.64 oz.2.6 oz.9.6 oz.19.2 oz.35.2 oz.80.0 oz.Surfactant0.250.32 oz.1.3 oz.4.8 oz.9.6 oz.17.6 oz.40.0 oz.Dye0.250.32 oz.1.3 oz.4.8 oz.9.6 oz.17.6 oz.40.0 oz. Educational programs of Texas Cooperative Extension are open to all people without regard to race, color, sex, disability, reli Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amenJune 30, 1914, in cooperation with the United States Department of Agriculture. Chester P. Fehlis, Director, Texas Cooperative Texas A&M University System. Biology and Management African rue grows in many types of soil, including alkaline and saline soils. It spreads rapidly intodisturbed areas, roadsides, oilfield pads and desertified rangeland. It may contain allelopathic sub-stances that prevent the growth of other plants. Managing toxicityAfrican rue is toxic to cattle, sheep and probably horses. The most toxic parts of the plant are theseeds and fruits, with a lethal dose of 0.15 percent of the animalÕs body weight. Young leaves are alittle less toxic and dry leaves are apparently nontoxic. Fortunately, the plant is very unpalatable tolivestock and most will eat it only if forced to by starvation or mineral deficiencies.poisoning in animals are:loss of appetitelistlessnessweakness of the hind legsknuckling of the fetlock jointspoisoning in animals are:stiffnesstremblingincoordinationfrequent urinationThe body temperature of poisoned animals is usually below normal. They salivate excessively, wet-ting the lower jaw and muzzle. Post-mortem examination may reveal hemorrhages in the heart andliver. The most dangerous time of the year for livestock is spring and summer when the plantÕs seedsare present and acute poisoning may occur. Do not graze areas infested with African rue duringthis time, especially if little other grazeable forage is available. If symptoms of chronic poisoningappear, remove animals and give them good quality feed and water; chronic poisoning cases gener-ally recover.Maintaining a proper stocking rate is the first step in preventing toxicity problems. Do not over-graze land, especially if this could force animals to consume African rue. Controlling African rueWhere African rue dominates the plant composition and has replaced desirable native plants, it mayneed to be controlled. Given its aggressive nature, the plant is extremely hard to control withmechanical techniques. Mowing or blading causes the plant to re-sprout and spread. Grubbing individ-ual plants is nearly impossible because the roots are too deep to dig out and any root left in theground may re-sprout. Continued grubbing year after year may eventually control individual plants.Repeated deep cultivation (10 to 12 inches), combined with re-seeding perennial plants, has beensomewhat successful but is expensive.The most practical and economical way to control African rue is with herbicides. Treatments are spe-cific, depending on the type of soil and the environmental conditions. Use broadcast methods to treatlarge areas that are heavily infested. Use individual plant treatment methods for smaller areas or scat-tered infestations.For large areas densely infested with African rue, broadcast Spike 20Pª, a pelleted herbicide thatworks best in loose soils such as sand, loamy sand or sandy loam. It can be applied with groundapplication equipment.To treat smaller areas or sparsely scattered plants, apply Velpar Lª, a herbicide that must penetrateinto the root zone. Apply it undiluted to the soil directly below the plant canopy. Velpar Lª is nonse-lective and will kill grasses in the immediate application area.Both Spike 20Pª and Velpar Lª can move off the application area and should not be used on slopesor near desirable plants. Table 1. Recommendations for controlling African rue on rangeland.HerbicideBroadcast rateIndividual plant (a.i./acre)treatment rateTime to applyRemarksSpike 20Pª1.5 poundsAnytime of yearDo not use when plants are growing on heavy clay or compact caliche soils.Velpar Lª2 ml/foot of canopyApril through Do not use when plants Octoberare growing on heavily compacted caliche soils. Flower and fruit RootSeedlingFall regrowthAfrican rue on roadside