Twenty two different knapweed (Centaurea sp) species are well established in the United States. Four of these knapweed overlap in distribution and share similar morphological characteristics. This includes spotted (C. stoebe), brown (C. jacea), black (C. nigra) and meadow knapweed (C. xmoncktonii). The key to separating these and other knapweed species are the involucre bracts.Read More
Twenty two different knapweed species (Centaurea sp) are well established in North America. Most are introduced opportunists that have aggressively invaded natural areas, pastures, open woodlands, rights-of-way, and disturbed areas. Brown (C. jacea), black (C. nigra) and meadow knapweed (C. ×moncktonii) are long-lived perennial plants that are problematic in the United States and southern Canada.Read More
Invasive plants often establish and flourish on steep, rough terrain that is difficult to access. This makes early detection and management difficult and hazardous work. Nigel Davis, a commercial applicator in Helena, Montana, understands the challenges involved with treating invasive plants in natural areas with ground-based equipment. “Some of our application sites are really remote, and between the snakes and steep terrain it’s labor intensive and dangerous” says Davis. “We needed to find a better, more efficient way to treat these infestations.”
Davis became interested in the use of drones, or unmanned aerial vehicles (UAV), to treat invasive plants about a year ago. He looked at various companies and models available and selected a model produced by a company located in the United States.
“I wanted to work with an American company and needed a drone that could handle at least a four-gallon payload capacity. There are lots of different options for tank capacities, but I opted for a 4 gallon unit for longer battery life that would still let us meet objectives” Davis explains.
The drone is outfitted with a 4-gallon tank, pump, a six-foot boom, and six nozzles. Davis did his own testing to determine which nozzles provided the best coverage for areas he was typically spraying. The nozzles he selected produce a 12-foot pattern with a 24-inch average overlap when spraying. He calibrated the drone sprayer output and checked its application pattern with spray cards, to ensure accuracy and coverage. He also had to make a few adjustments to the boom angle, and is considering taller landing gear to protect the booms.
The drone can treat from one to four acres with the four-gallon tank, depending on site conditions and customer specifications for application volume. “I have complete control of the volume output and speed, so I can manipulate application rate dependent on each unique situation” says Davis.
In a typical application, the ground speed is five meters per second at a height of five meters. It takes about four minutes to spray one acre. Davis explains that the speed and altitude can be adjusted depending on the environment where you are working.
Along with studying for and passing the Federal Aviation Administration drone certification exam, it still takes time and practice to become proficient flying the drone. “There is always a learning curve with any new technology, and flying a drone is no different,” says Davis. “We felt comfortable after about 10 to 12 hours of flying time, but that will vary among different operators.” He currently uses the drone to treat invasive plants on steep, rocky terrain—areas that are unsafe to traverse on foot or with all-terrain vehicles.
“We limit flying time to about five hours a day, from early morning to about noon, depending on wind and temperature, he says. “I still find that my motor skills get tired working the controller, and my brain gets tired operating flight controls”.
About half of the target areas can be treated by uploading the infested area to the drone GPS and using autopilot to fly the established grid. After treating the area, the drone returns to the launch spot and lands. It is completely GPS controlled if that option is selected.
Infestations that can’t be uploaded to the GPS are flown by hand, which requires the operator to see the entire infestation. In these situations, Davis positions himself near the target infestation where he can also see his launch-based ground crew. When the drone needs refilling or a new battery, Davis flies it back to the launch site to be resupplied then returns it to complete the application. Trees are also an issue, so he hand-flies the drone for spot-treating infestations near trees.
“It’s nice not to have to worry about rattle snakes anymore! Well, not as much anyway!” says Davis.
Davis plans to add a camera to the drone after he gains more experience. “Flying a drone via a camera and drone goggles is more difficult, so we wanted to visually fly it for a while” he explains. “A camera will allow us to locate weeds, set a GPS point on the infestation, and then program the drone to go back and spray those locations. The capability is there, we just haven't done it yet.”
Davis treated a total of 35 acres of invasive plants with the drone this season, primarily targeting spotted knapweed and leafy spurge. The application rate for spotted knapweed is 3.3 ounces of Opensight® specialty herbicide per acre. Leafy spurge on grazed land is treated with 1 quart of Tordon® 22K herbicide per acre. Liberator was added as a surfactant and drift agent at 0.25 percent volume-to-volume. Visual assessments of spotted knapweed and leafy spurge control the season of application indicate that drone-applied herbicide treatments provided good to excellent control of both species.
Benefits of Drone Application
Davis believes that using a drone for herbicide application may have distinct advantages, especially on rugged terrain. These include easy access to remote infestations, zero foot print (wheel tracks) on the ground, reduced applicator exposure, reduced herbicide drift, and cost-effective control.
“A really important advantage of the drone is that it keeps our employees from attempting hazardous terrain with all-terrain vehicles or backpack sprayers. We can also reduce the amount of herbicide solution we apply because we can put the herbicide exactly where we want it without having to treat the entire hillside or field” he explains.
Tips and Advice
Along with his certification as a commercial herbicide applicator, Davis is a pilot with more than 3000 hours of fixed-wing aircraft time. “Being a pilot is a huge help in flying drones” he says. “You already understand FAA airspace regulations, basic aerodynamics, weather, and wind. This knowledge is really important for safe flight and also makes the test for becoming a FAA Part 107 drone pilot much easier.”
Davis has advice for people considering purchasing a drone for invasive plant management. “One of the most important things you can do is work with an American manufacturer with operations in the United States. You are pretty much assured that a mishap or crash will occur, and you will need advice on how to fix it, or there may be issues with computer programming, or the controller, battery, charger, etc. It's nice to be able to contact help within similar time zones as ours.”
Davis asserts that drone technology has an important future in invasive plant management. “Based on our work this summer, I believe that drones have the ability to greatly expand the capability of private and public land managers for invasive plant detection and control in natural areas.”
More information on Drones
®™ Trademarks of Dow AgroSciences, DuPont or Pioneer and their affiliated companies or respective owners.
Opensight® 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. Consult the label before purchase or use for full details. Always read and follow label directions.
Tordon® 22K herbicide is a federally Restricted Use Pesticide. Always read and follow label directions.
Absinth wormwood (Artemisia absinthium L.) is a perennial broadleaf plant introduced as an ornamental into North America from Europe in 1841. The plant escaped cultivation and is now widely distributed in the U.S. and Canada. This article describes the biology, ecology, identification, and management of absinth wormwood in natural areas.Read More
Herbicides are an important tool for removing noxious or invasive weeds from plant communities, allowing desirable vegetation to respond. Field research trials were established to determine if warm and cool season grasses could be planted either in late autumn as a dormant fall planting or in the spring after a September application of herbicide.Read More
Japanese chaff flower (Achyranthes japonica) is a highly invasive, non-native, perennial plant in the Amaranth family. This article discusses distribution and management of this non-native plant.Read More
Guy B. Kyser, Vanelle Peterson, Steve B. Orloff, Steven D. Wright, Joseph M. DiTomaso (2011). Invasive Plant Science and Management: July-September, Vol. 4, No. 3, pp. 341-348. http://wssajournals.org/doi/abs/10.1614/IPSM-D-11-00002.1Read More
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
A summary of research presented as a poster–Integrated Management of Yellow Starthistle with Burning, Aminopyralid (Milestone), and Revegetation–at the Western Society of Weed Science Annual Meeting, Reno, NV 2012 by Guy B. Kyser, Arthur W. Hazebrook, and Joe DiTomaso.Read More
Fall rain and cooler temperatures provide good conditions for extending the herbicide application season. The following species and many others can be effectively controlled in the fall. Follow the links for control recommendations for each species.Read More
This TechNote summarizes research on: 1) Integrating herbicides with other methods for managing yellow starthistle and 2) Controlling coast fiddleneck (Amsinckia menziesii)and yellow starthistle. Also included are practical management tips on herbicide rate and time of application to optimize yellow starthistle control.
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.
Practical guidelines for cleaning and winterizing your truck-mounted, ATV, or backpack sprayers.
Proper cleaning and winterization of herbicide application equipment is important to ensure safe storage over the winter. Spending a little extra time in the fall will save you time and money next spray season!
2010. Proceedings Western Society of Weed Science. V63: p44.
Ruth Richards*, Big Horn County Weed and Pest Control District, Greybull, WY; Mary B. Halstvedt, Dow AgroSciences, Billings, MT and Tom D. Whitson, University of Wyoming, Professor Emeritus.
Big Horn County is located in north central Wyoming. Russian olive, Elaeagnus angustifolia, was listed as a state noxious weed in 2007. Russian olive removal projects were initiated across the state. A standard treatment program involves the mechanical removal of all above ground growth followed by a foliar treatment to regrowth. Standard herbicide recommendations for treating the regrowth proved to be inadequate. The objective of this project was to identify an effective herbicide, rate and timing. Russian olive trees were mechanically removed in February 2008 using a mulcher mounted on a skid steer. Plots were set up as a randomized complete block with three repetitions. Treatments included two timings: 5 months (July 2008) after removal when regrowth was 2-4 feet tall and 8 months (October 2008) after removal to regrowth from 3-8 feet. Early timing treatments were triclopyr ester alone at 2, 3, and 4 lb ae/A (2, 3, and 4 qts/A Remedy® Ultra/Garlon® 4 Ultra), triclopyr ester plus aminopyralid (Milestone®) at 2+ 0.11 lb ae/A (2 qt + 7 fl oz/A). Later timing treatments were triclopyr ester alone at 2 and 3 lb ae/A, triclopyr ester plus 2,4-D at 1 +1 lb ae/A, triclopyr ester plus aminopyralid at 2+0.11 lb ae/A, aminopyralid+metsulfuron at 0.11+.02 lb ae/A (Chaparral® at 3.3 oz/A), and triclopyr amine at 3 lb ae/A (Garlon® 3A at 4 qts/A) plus aminopyralid at 0.11 lb ae/A. All treatments included 1 qt of MSO/A. Plots were visually evaluated for percent control 1 YAT in October 2009. None of the early treatment plots yielded acceptable levels of control. In the later application timings, triclopyr ester at 2 lb ae/A plus aminopyralid at 0.11 lb ae/A yielded the highest control at 97%. Triclopyr ester at 3 and 4 lb ae/A both showed 93% control. Triclopyr ester at 2 lb ae/A provided only 66% control. The treatment that provided the lowest level of control at 47% was the triclopyr ester tank mixed with aminopyralid+metsulfuron at 1 lb+.11+.02 lb ae/A. Applications in July will not provide effective control of Russian olive regrowth. Treatments applied in October when there was more regrowth were significantly more effective. Adding 0.11 lb ae/A (7 fl oz/A) of aminopyralid to 2 lb ae/A (2 qt/A) triclopyr ester improved Russian olive control to 95% from 66% when triclopyr ester was applied at 2 lb ae/A alone.
®™ Trademarks of Dow AgroSciences, DuPont, or Pioneer and their affiliated companies or respective owners.
The USDA Plants database lists more than 20 Rubus species (and associated hybrids) that were introduced to North America. Himalayan blackberry (Rubus armeniacus) and cutleaf blackberry (Rubus laciniatus) are the two most widespread of the invasive blackberry species.Read More
Fall is an excellent time to control invasive weeds with Milestone. Late summer and fall rains in many areas of the Central Plains and the West will provide land managers with a good opportunity to extend their application season.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.
Plants in the carrot (Apiaceae) family share the characteristic of an umbel-shaped flower head. The family includes hundreds of plants, some that are valuable vegetables and herbs, and a few that are masters in chemical warfare. Accurate identification is important for management and avoiding accidental poisoning. This article reviews distribution, identification and management of three invasive, toxic plants in the carrot family: poison hemlock (Conium maculatum), wild parsnip (Pastinaca sativa), and giant hogweed (Heracleum mantegazzianum).Read More
The carrot (Apiaceae) family comprises 434 genera and about 3,700 species and is characterized by a flat-topped flower cluster, called an umbel. Water hemlock (Cicuta), one of several toxic members of this family, is considered to be the most toxic plant in North America. There are four species of water hemlock in North America, all highly poisonous and native to North America: spotted (C. maculata), western (C. douglasii), bulblet-bearing (C. bulbifera), and Mackenzie’s (C. virosa).Read More