19 Mar What are some options for organic brush control?
D.H.KansasAnswer: Brush control can be done in a variety of ways without using chemicals that are prohibited for use under USDA’s organic standards. You will need to weigh the information below with your own experience to date with the practicality and feasibility of each proposed method. You can design a combination of management strategies to provide the best control for a variety of non-native, invasive plants. If you review the articles referenced below, please disregard any references to herbicide materials (that would be prohibited in organic systems). Instead, look at the information about plant life cycle and growth habits, and the non-chemical approaches to managing brush that may be both helpful and allowed within an organic system. Management Ideas and Tools: General tips: A first step toward effective management strategies is to properly identify the species you wish to control, and to understand the life cycle and growth habits of the plant(s) The best treatment is often a combination of complementary treatments. Strategic timing can make any given approach much more effective. On the other hand, bad timing could make things worse by stimulating growth. Physical controls will be most effective when done when roots are most exhausted, such as in the spring after budbreak, or during a drought. Hand Removal/Physical Uprooting: Pull out the small plants including the roots. Hand pulling works best when the soil is moist and the plants are less than 3/8 inch diameter (2). As you pull plants, avoid excessive soil disturbance to avoid bringing up new seeds that may be buried in the soil (1). Many types of seeds can remain viable in the soil for many years, such that follow-up control of seedlings that emerge later is essential (2).Tools such as a “Weed Wrench” or “Root Talon” can help pull stems up to 2.5 inches in diameter. The “Weed Wrench” comes in four different sizes, with jaws that open from 1″ to 2.5″, with the larger ones clearly being bigger, heavier tools. Their website provides some guidelines for use and selection: The Weed Wrench Co. http://email@example.com Toll Free: 877-484-4177 Phone: 541-471-2012 Fax: 541-471-4120The Weed Talon appears to have been designed for removal of buckthorn, but seems that it would work on a variety of species. http://roottalon.com Lampe Design, LLC (651) 699-4963. A review of this tool is available at http://tncweeds.ucdavis.edu/tools/rtalon.html.Cutting: Cut off larger plants that cannot be pulled up by their roots; then cover the cut surface to prevent resprouting. Materials you use to cover the stumps might be as simple as something to prevent light from reaching the cut, such as a can or black plastic. The best time to cut and chemically treat the stumps is in late summer and throughout the fall (2). Keep track of the location of the cut trees so you can check whether they are re-growing, and if they are, address any re-growth promptly. Grazing animals: Woody perennials have a variety of physical and chemical defenses (i.e. thorns and unpalatable elements) to avoid being browsed. Goats are good at eating woody perennials. Their digestive systems are well adapted to getting nutrients form woody material, and their larger livers allow then to detoxify substances such as tannins and terpenes. However, multiple species can also be useful. Timing of grazing is important. Grazing goats, sheep, cattle or other animals in the summer removes foliage and can help exhaust root reserves when they otherwise would be building up for the dormant season. However, fall and winter foliage may be more palatable and less toxic. High stocking density for a short period of time (not overgrazing) can reduce selectivity in grazing to increase shrub consumption. Feeding high protein supplements can also help increase consumption of woody material. These and many other ideas can be found in the resource “Targeted Grazing: A natural approach to vegetation management”. This reference is a wealth of information by many authors with a great deal of experience in the field. Chapter 9 is entitled Targeted Grazing to Control Weedy Brush and Trees, written by Erika Campbell and Charles A. Taylor, Jr. It covers tips on breed selection, selective breeding, timing, stocking rate, as well as considerations for animal production. Chapter 18 of this book is entitled “Additional Resources for Targeted Grazing” is also noteworthy. Two of its writers are ATTRA specialists Linda Coffey and Margo Hale. Mechanical scraping: The bark of brush and saplings can be scraped off using a “bush scraper” pulled behind a tractor or draft animals. This may scrape all the bark off one side of the saplings, interfering with the transport of water and carbohydrates. The author commented, “The speed of death is important because in cases where the plant suffers a severe shock, such as fire or breaking, it sends a message to send out new growth from the root.” “In a slow death the plant never really gets the message it’s dying.” The scraped area also becomes a prime entrance location for disease and insects which inadvertently help control the trees. In this case study, scraping was followed by a spring burn to clean up the dead material.Flaming: Flaming means heating a plant’s tissues with a propane torch. This technique can provide effective non-chemical alternatives to kill new sprouts. It is like cooking tender green shoots, and should not be confused with actual burning where the plant catches fire. Like other strategies, the timing of treatment is important. Flaming should be done when the plants are small, tender and moist. With relatively little fuel, you can knock back the plants when they are weakest, and prevent strong regrowth. Prescribed Burning: Fire is one method proposed for controlling woody perennial seedlings in fire-adapted areas. Certified organic operations should check any plans for burning with their certifiers for clarity of permissibility. USDA’s National Organic Standards section 205.203 (e) states that, “The producer must not use burning as a means of disposal for crop residues produced on the operation: Except, that, burning may be used to suppress the spread of disease or to stimulate seed germination.” As you describe your weed management strategies, you will want to include a description of any proposed burning. Under most circumstances, invasive species should not be considered crop residue, but it is good to have agreement about your plans.Timing for burning is recommended in the Midwest from late March to early May, or as soon as leaf litter is dry. Resprouting after burning at this time will be less vigorous due to the low carbohydrate levels in the plants in early spring. Repeated burning of established stands may be required every year or two-to-three years for 5-6 years or more (1, 2). Prescribed fire may be ineffective and therefore unsuitable in low litter areas. In dense stands, seedlings and saplings may be cut and allowed to dry on site to create fuel for future fires. Even with plants that are vulnerable to fire, one needs to be vigilant about managing any resprouting that occurs. (1). Replanting with Desirable Plant Species: After brush control, it may be helpful to replant your site with desirable trees, shrubs, or herbaceous plants. Clearly, the plants you choose will depend on your intended land use, whether it is to be a natural or agricultural area.References:(1) PCA Alien Plant Working Group(2) Buckthorn: What you can do! – Invasive species: Minnesota DNR(3) Controlling Aspen Regrowth with Grazing. Daniels, Calvin, Stockman Grassfarmer. February 1995, p. 30.(4) Targeted Grazing: A natural approach to vegetation management. A handbook on grazing as a new ecological service.2006 ASI, A. Peischel and D.D. Henry, Jr.(5) The Nature Conservancy Weeds