Tis the season for frost as evident to some in the United States that are experiencing a roar from Ol’ Man Winter. As a grower, having an overall sufficient orchard floor management strategy is key to assuaging such concerns. A vegetation-free strip is one of the tried-and-true ways of providing warmth to the soil as well as ensuring its nutrition.
The use of herbicides is a key component in the establishment and maintenance of such a method. In an essay from the North Carolina Cooperative Extension, it states, “The vegetation-free strip method is superior to all other orchard floor management options. Vegetation under the tree competes for nutrients and water resulting in reduced growth, yield and small fruit.”
Although the vegetation-free strip is the most common practice, there are alternative strategies available. For example, legumes are sometimes applied to give the orchard a bump in nitrogen; however, a grower may find difficulty in controlling the timing of its availability. It also may increase the number of arthropods that’ll feed off the crop.
“Although legumes add nitrogen to the orchard soil, the fertility benefit may not overcome the cost of managing increased arthropod pest populations,” stated Brent Black, Grant Cardon and Marc Rowley of Utah State University in the essay “Alternative Orchard Floor Management Strategies.”
Another practice is applying mulch; some variations include wood chips, paper, weed fabric or straw. Some growers have ventured into organic material. They do keep the weeds down but with annual application the costs can add up if growers don’t have a readily available source for material.
“The most significant problem is that mulches create an ideal habitat for voles. Also, additional nitrogen may be needed to support the microorganisms that drive decomposition of organic mulches,” the North Carolina Cooperative Extension essay noted.
Weed fabrics derived from polyester and polythylene, for example, help the soil to breathe and water to pass through but can be a pricey initial investment.
Not to discount the alternatives, legumes and mulches also bring something to the table despite their drawbacks. However, with the vegetation-free strip, a grower has the advantage of solid grass cover and clean cultivation.
“The grass alley provides a solid place for equipment travel, helps prevent soil erosion, and helps increase water infiltration,” stated Teryl R. Roper, professor of horticulture at the University of Wisconsin-Madison and University of Wisconsin-Extension in the essay, “Orchard Floor Management for Fruit Trees.” “Sod also helps to maintain soil structure. Depending on the cover crop sown, weed invasion can be minimized and sod establishment can be fairly quick.”
With the application of a herbicide, it’s best to create a “weed-free” zone of up to 3 feet alongside the rows of young trees. An interesting method offered by North Carolina Cooperative Extension, is “to apply white latex paint to the bottom 2 to 3 feet of the tree trunk of newly planted trees before applying herbicides.
The Extension noted that by accomplishing this, it lowers the chance of injury from the winter or postemergence herbicides – agents used to fight existing weeds.
“Dip a car wash mitt (wear rubber gloves underneath the mitt) in paint and rub up and down the tree trunk until it is completely painted,” the Extension stated.
Of course, before a grower applies any type of herbicide it is always wise to read the manufacturer’s label and instructions.
“Herbicides, like all pesticides, must always be applied in accordance with label directions,” Roper stated in his essay. “Herbicides should be applied with a low-pressure, boom-type sprayer fitted with flat fan-type nozzles. Low-pressure nozzles and pressures of 20 to 35 pounds reduce drift to non-target plants. Don’t spray into the wind!”
As with most applications, there are many herbicides that may or may not fit your orchard floor management goals. For more information about application, visit your county’s cooperative extension agent.