Saltcedar (Tamarix ramosissima, T. pentandra, T. chinensis, and T. parviflora) and Russian olive (Elaeagnus angustifolia L.) are rapid growing, non-native deciduous trees that were introduced into the United States for erosion control (saltcedar), windbreaks (Russian olive) or as ornamental plantings.Read More
by CELESTINE DUNCAN
Autumn olive is an invasive woody shrub or small tree that grows to about 20 feet in height.
The shrub is widespread in the eastern third of the United States and Ontario, Canada (Figure 1). Autumn olive is native to Asia and was introduced to North America around 1830 for ornamental use, soil stabilization, strip-mine reclamation, and food and cover for wildlife.
Autumn olive is one of the first plants to leaf out in spring and grows rapidly, leading to suppression of native plants. The shrub establishes in a wide range of habitats and has nitrogen-fixing root nodules that allow it to grow on nutrient-poor sites. The plant is commonly found invading open and early-successional woodlands, abandoned agricultural fields, and edges of streams and rivers.
Autumn olive and Russian olive (Elaeagnus angustifolia) share similar habitat and invasive characteristics; however, autumn olive is more widespread in the eastern half of the United States, and Russian olive is more prevalent in the West. A comparison of vegetative characteristics between autumn olive and Russian olive is available at: bit.ly/Autumn-Russian-Olive.
There are several management options for autumn olive, depending on tree size, density, and environmental constraints. The following information discusses effectiveness of various management methods. (For detailed information on controlling Russian olive, go to bit.ly/saltcedar)
Small trees that are not well established can be removed with a weed wrench or dug with a spade when soil is moist. Digging must remove the entire root system, so the plant does not resprout.
Larger trees can be removed with a tractor, skid steer, or backhoe. This will cause significant disturbance, and follow-up management will be needed to restore the site to minimize soil erosion and invasion of other non-native plants. Roots remaining in the soil will likely resprout, so a foliar herbicide treatment will be necessary to stop reinvasion.
Cutting the shrub at the base will cause prolific sprouting and increase the number of stems if a herbicide is not applied to the cut surface. An effective strategy for controlling autumn olive is to kill both the above-ground portion and the root system, which eliminates the potential for resprouting. This is most effectively achieved through herbicide use.
Selective systemic herbicides will effectively control autumn olive. Sites will need to be monitored for possible resprouts and new seedlings that germinate following application.
Results of field trials conducted in Virginia, Pennsylvania, and Indiana show that Vastlan® specialty herbicide (Garlon® 3A), or Garlon® 4 Ultra specialty herbicide alone or in combination with Milestone® specialty herbicide, will control autumn olive without injury to desirable understory grass vegetation. The addition of Milestone improves autumn olive control and also provides broadleaf weed control on species such as knapweed and thistle. Desirable plants remaining on the site will compete with autumn olive resprouts and germinating seedlings, decreasing the potential for reinvasion. There are several herbicide application options described below, depending on tree size, density, and management equipment available.
I. High-Volume Foliar Treatments to Individual Trees (smaller than 6 feet in height)
Foliar spraying is a method of control in which herbicide is sprayed directly on the leaves. Herbicide application needs to occur after the plant is in full leaf and before the onset of fall color in order to maximize effectiveness.
Herbicides are generally applied to wet the leaves, but not to the point of runoff. Treatments can be made to autumn olive shrubs smaller than 6 feet in height. It is important to calibrate your equipment to determine the amount applied per acre, including application made with a backpack sprayer or hand gun from a main tank. Typically, about 100 gallons per acre (GPA) are sprayed when “spraying to wet” without any runoff from the leaves. At an application volume of 100 GPA, mix 7 fluid ounces (0.05% v/v) of Milestone® specialty herbicide and 4 quarts (1%) of Garlon® 4 Ultra specialty herbicide in 100 gallons of water with 1 quart (0.25% v/v) of a non-ionic surfactant.
For small infestations and follow-up spot treatments, mix 1.3 fluid ounce of Garlon 4 Ultra with 2.1 cc’s of Milestone (use a syringe to measure the Milestone) in one gallon of water with a non-ionic surfactant, and spray to wet foliage. The addition of Milestone to the mix will improve autumn olive control and will also control associated noxious and invasive weeds.
II. Foliar Treatments to Resprouting Autumn Olive after Mowing or Cutting
Autumn olive will resprout following cutting, mowing, or shredding operations. Wait at least six months after cutting, until resprouts grow to 3 to 4 feet tall, before applying the herbicides. This allows time for plants to regrow and develop adequate leaf area for more herbicide uptake from a foliar application. This may mean the application will need to occur the year after cutting, or, at least, in late summer after a previous winter mowing. It may also occur earlier in the spring of the same year.
Autumn olive resprouts can be controlled with a foliar application of Milestone® at 7 fluid ounces per acre (fl oz/A) plus Garlon® 4 Ultra at 4 quarts per acre (qts/A) with a non-ionic surfactant. See the high-volume foliar treatment above for mixing guidelines.
III. Low-Volume Basal Bark Applications
This treatment method is effective on trees with stems up to, but not larger than, 6 inches in diameter (Figure 2). The herbicide application can be made any time of year, including winter months, except when the bark is wet or frozen, or frost is present on stems. Applications are easier on grazed sites or during late fall to early spring when there is little foliage to intercept the spray. Another advantage to treatment this time of year is that many desirable plants are dormant, and selectivity can be improved. For best results, herbicide applications should be avoided during rapid growth of autumn olive in the spring.
A mixture of Garlon® 4 Ultra in an oil carrier is very effective for low-volume basal bark applications. An oil carrier ensures good coverage and herbicide absorption through the bark. The recommended concentration of Garlon 4 Ultra is 20% (see Table 1 for mixing recommendations).
Be sure to adjust the sprayer nozzle to deliver a spray that matches the size of the stem (use an adjustable solid cone nozzle). Spray the herbicide mixture lightly but evenly (similar to using spray paint) on the plant’s stem or trunk, from ground level up to 12 to 15 inches, and on any exposed root flares (Figure 2). Apply the mixture to all sides of every stem, but not to the extent that runoff and puddling occur at the crown or root collar. Autumn olive with old, rough bark may require individual stems to be treated from ground level to a height of about 15 to 18 inches.
Spray solutions are made with oil. Use oil carriers such as basal oils, diesel, kerosene, seed oils, or other oils with instructions for basal and cut-stump applications. Precaution: Soil oils are more viscous at low temperatures and harder or impossible to use in cold temperatures. Herbicides and basal oil need to be registered or accepted for use on the type of site where the treatment occurs.
IV. Basal Cut-Stump and Cut-Stump Application
Basal cut-stump treatments involve cutting six inches above the ground level, followed by herbicide application (Figure 3 and 4). Apply the herbicide solution (Table 1) to the sides of the stump, including the root collar area, the outer portion of the cut surface (cambium), and any exposed root flares (Figure 4) until thoroughly wet but not to the point of runoff. Avoid cutting followed by herbicide application during heavy sap flow, since this can interfere with penetration of oil-based basal mixes and decrease control. Heavy sap flow can also carry the herbicide mixture off the stump, resulting in poor control. While it is customary to treat soon after cutting, applications may be made any time after cutting (for example, cut in winter and treat the following spring), but should occur before resprouting.
Cut-stump treatments involve cutting the tree close to the ground and applying herbicide only to the exposed cambium (Figure 3). Cut-stump treatments are very effective for controlling autumn olive and can be used any time of the year as long as the herbicide does not freeze when applied, and the tree is not frozen. When using Vastlan® specialty herbicide cut stumps should be treated immediately (within 30 minutes) after cutting. When using Garlon® 4 Ultra specialty herbicide, applications can be made up to one week after cutting, but before resprouting begins (Table 2).
Monitor autumn olive that has been manually removed or treated with herbicide for at least two years to determine if complete control has been achieved. Shrubs that resprout or are not completely killed by the first treatment will require a follow-up treatment. Label recommendations should always be followed to maximize the potential for successful control.
Burch, Pat. Field Scientist. Dow AgroSciences.
Dow AgroSciences. Unpublished field trial data.
EDDMapS. 2018. Early Detection & Distribution Mapping System. The University of Georgia — Center for Invasive Species and Ecosystem Health. Available online at www.eddmaps.org/
Munger, Gregory T. 2003. Elaeagnus umbellata. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available online
www.feis-crs.org/feis/ [2018, January 1].
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow.
State restrictions on the sale and use of Garlon® 4 Ultra specialty herbicide apply. Consult the label before purchase or use for full details. Milestone® and Vastlan® specialty herbicides are not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state.
Milestone: When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. State restrictions on the sale and use of Milestone apply. Consult the label before purchase or use for full details. Always read and follow label directions.
BY CELESTINE DUNCAN
Scentless chamomile, also known as daisy or scentless false may-weed (Matricaria perforata or Tripleurospermum perforatum), is an annual, biennial, or rarely perennial forb. The plant is native to Europe and was likely introduced to North America in the 1930’s as an ornamental or crop-seed contaminate. The weed is widespread in Canada, Alaska, and much of the United States (Figure 1). It establishes well in moist, disturbed areas along streambanks, meadows, riparian areas, pastures, and hayfields.
Scentless chamomile reproduces only by seed, with individual plants capable of producing more than 300,000 seeds a year.
Seed can be widely dispersed on equipment, in contaminated crop seed and feed, and by water. Seedlings germinate primarily during spring and fall, forming a dense mat, especially on disturbed areas. Fall-germinated seedlings overwinter and are usually the first to flower in spring. The seed does not need a dormancy period to germinate and can remain viable for up to 15 years when buried in soil.
Flowering occurs from May through October, depending on moisture. Flowers have a yellow central disk surrounded by while petals, similar to oxeye daisy (Fig. 2 and Sidebar: What’s the Difference Between Scentless Chamomile and Oxeye Daisy). Flowering stalks are slender, branched, and from six inches to three feet in height. Leaves are alternate, fernlike, finely divided, and odorless when crushed (Fig. 3). This is not the chamomile used as a tea.(1)
Scentless Chamomile is not competitive in healthy perennial plant communities. However, it quickly colonizes disturbed sites and can reduce establishment of desirable native vegetation. Although most grazing animals avoid the plant, it has been observed to cause blistering on livestock muzzles and irritation to mucous membranes.
The key to effective management of scentless chamomile is prevention, early detection, and control. Eradication is difficult once the invasive plant has established and produced seed. Transportation networks, such as road and railway systems, serve as corridors for scentless chamomile spread. Maintaining weed-free road and railway right-of-ways, cleaning equipment, and tarping hay/grain trucks will reduce seed spread. Seeding desirable perennial vegetation on disturbed sites will reduce establishment of scentless chamomile.
Several selective broadleaf herbicides will effectively control scentless chamomile, including Transline® and Milestone® specialty herbicides. Scentless chamomile is reported to be resistant to 2,4-D, and applicators should alternate between different herbicides to reduce the possibility of developing herbicide resistance.
Field trials were conducted at more than 32 sites in North America to determine the effectiveness of Milestone on scentless chamomile. Plant growth stage at application ranged from rosette to late-bud. Results of studies showed that applying Milestone at 4 to 7 fluid ounces per acre (fl oz/A) from the rosette to the pre-bud growth stage provides good control of scentless chamomile. Optimum control is achieved when plants are 12 inches in height or less. Scentless chamomile plants treated at the flowering growth stage are still capable of producing seed. The addition of metsulfuron-methyl to Milestone does not significantly improve control over Milestone applied alone.
Areas with desirable herbaceous vegetation should not be treated with a non-selective herbicide, such as glyphosate. Vegetation growing on the site will be killed or injured with a glyphosate application thus eliminating desirable plants that compete with newly germinating scentless chamomile.
Mechanical and Manual Control
Mowing can reduce seed production in pastures, hay land, and non-cropland. The plants should be cut before the flowers are fully formed; however, plants will flower below the cutting height. Repeated mowing can also reduce the competitive ability of desirable vegetation, causing an increase in scentless chamomile seedling establishment.
Tillage effectively controls scentless chamomile seedlings on pasture or cropland. Frequent, shallow tillage will kill seedlings. Deep cultivation should not be used because it buries seed and extends the longevity of seed viability in soil.
Hand-pulling is effective on small infestations and can prevent the spread of scentless chamomile into new areas. Plants that are flowering should be bagged and removed from the site.
Two insects are established for the control of scentless chamomile in Canada: Omphalapion hookeri, a seed-head-feeding weevil from Germany was released in British Columbia in 1992 and reduces seed production in scentless chamomile; and Rhopalomyia tripleurospermi, a gall midge from eastern Europe, released in British Columbia in 1999 reduces scentless chamomile vigor and flowering ability. Both insects are listed as established and dispersing in Canada. In the United States, collection and release of these two agents has not been approved by Animal Health Inspection Service (Merenz pers. comm.).
Land management practices that improve desirable plant competition reduces establishment of scentless chamomile and increases effectiveness of management methods. Practices that increase the competitiveness of desirable plant species and communities—such as proper grazing management, critical area planting (e.g. following wildfire or disturbance), and seeding competitive forage on hay and pastureland—will make the environment less suitable for invasive plant establishment and spread. Use of selective broadleaf herbicides can effectively remove scentless chamomile from desirable grassland communities. With any management method, follow-up monitoring after treatment is important to control seedling populations germinating from the long-lived soil seed bank.
Alberta Department of Agriculture. 2007. Scentless Chamomile Biology and Control. Agri-Facts Agdex 640-6. ( www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex871 )
British Columbia Ministry of Forest, Lands and Natural Resources. Omphalapion hookeri (Kirby) and Rhopalomyia tripleurospermi (Skuhrava). Accessed: January 1, 2018. Available online
( www.for.gov.bc.ca/HRA/plants/biocontrol/index.htm )
Dow AgroSciences. Internal field trial data.
Merenz, Richard. 2017. Personal communication. Plant Protection and Quarantine Officer, USDA APHIS PPQ. Helena, MT.
USDA, NRCS. 2018. The PLANTS Database (plants.usda.gov, January 1, 2018). National Plant Data Team, Greensboro, NC 27401-4901 USA.
1. People living in North America are familiar with chamomile tea, an infusion used to calm upset stomachs or to help with sleep. Two types of chamomile are used for health: German chamomile (Matricaria recutita) and Roman chamomile (Chamaemelum nobile).
2. Metsulfuron-methyl rate ranged from 0.37 to 0.45 ounces product per acre.
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow.
Milestone® specialty herbicide is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed, or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details.
State restrictions on the sale and use of Milestone and Transline apply. Consult the label before purchase or use for full details. Always read and follow label directions.
Native tallgrass prairies are diverse ecosystems that evolved with periodic disturbances such as fire and grazing pressure and are dominated by species that include big bluestem (Andropogon gerardii Vitman), Indiangrass [Sorghastrum nutans(L.) Nash], and switchgrass (Panicum virgatum L.).Read More
2010. Proceedings Western Society of Weed Science. V63: p43.
Byron Sleugh, Mary Halstvedt, Chad Cummings, Vanelle Peterson, Dow AgroSciences, Indianapolis, IN; and Robert G. Wilson, University of Nebraska Panhandle Research Center, Scottsbluff, NE.
Chemical control of saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia L.) has had varying degrees of success. Some non-selective herbicides cause unacceptable injury to desirable species or do not control invasive species under the canopy. Aminopyralid (Milestone®) controls many invasive herbaceous broadleaf weeds, but control of saltcedar and Russian olive has not been fully explored. Experiments were established to assess the efficacy of various aminopyralid containing products and aminopyralid and triclopyr (Garlon 3A or Garlon 4 Ultra) mixtures on these plants. Treatments included triclopyr amine and triclopyr ester at various rates plus aminopyralid at 120 g ae/ha (0.l1 lbs ae/acre) and Milestone® VM Plus at 9.6 L/ha (1 gal/acre) [triclopyr amine at 1.12 kg ae/ha (1 lb ae/acre) and aminopyralid 120 g ae/ha (0.11 lb ae/acre)]. At 326 days after application, 3.3 kg ae /ha (3 lbs ae/acre) triclopyr ester plus 120 g ae/ha aminopyralid provided excellent control (98%) of Russian olive and saltcedar (94%), similar to efficacy of imazapyr at 1.12 kg ae/ha (1 lb ae/acre). Triclopyr + aminopyralid treatments caused little to no grass injury (0 to 5%) compared to the imazapyr treatments (50 to 85%). Milestone® VM Plus at 9.6 L/ha provided 91% control of saltcedar and no grass injury. Adding aminopyralid to either the triclopyr amine or triclopyr ester was synergistic and provided increased control of Russian olive and saltcedar thus providing another option for controlling these species without significant injury to desirable understory vegetation.
®Trademark of Dow AgroSciences, LLC. Please read and follow all label instructions. 
Studies were initiated by the University of Hawai’i Cooperative Extension Service Invasive Weed Management Program to find a method to improve individual plant herbicide application techniques and determine efficacy of various herbicides applied as undiluted formulations.
Guy B. Kyser, Arthur W. Hazebrook and Joe DiTomaso (2013-in press) Invasive Plant Science and Management (DOI: 10.1614/IPSM-D-12-00094.1, http://pinnacle.allenpress.com/doi/abs/10.1614/IPSM-D-12-00094.1)Read More
Undesirable or invasive woody vegetation threatens the biology and ecology of prairie grasslands and native woodlands. Removing invading woody species can be accomplished year-long, with fall, winter and early spring herbicide applications, extending your vegetation management efforts.
Herbicides play an important role in integrated management of yellow starthistle and can be used alone or in combination with other techniques such as timely mowing, grazing, burning, or use of biological control insects.
Catastrophic fire seasons of recent decades prompted a number of agencies and researchers to synthesize and expand upon the knowledge-base related to invasive plant issues following wildfires. The following short list of literature reviews, handbooks, and recently published research provides a starting point for exploring issues and developing management guidelines related to invasive plants following wildfires.Read More