Miller, James H.; Manning, Steven T.; Enloe, Stephen F. 2010. A management guide for invasive plants in southern forests. Gen. Tech. Rep. SRS–131. Asheville, NC: U.S. Department of Agriculture Forest Service, Southern Research Station. 120 p.
Mulching for weed control is the use of materials to cover the soil surface that block light, thereby preventing weed germination and growth. While mulches and landscape fabrics are commonly used in restoration operations for reseeding and soil stabilization, mulches for weed control must be applied at rates high enough to prevent light from reaching the soil surface. Mulching is most effective on controlling small seeded species and is marginally effective on established resprouting perennials. There are many types of mulches including natural ones such as straw, bark, sawdust, crop residues, and grass clippings, and artificial ones such as paper, cardboard, and plastic. While mulch applications are not commonly made to control invasives on a large scale, they are still useful. For example, the use of a mulching machine for clearing privet and tallowtree can create a heavy mulch layer that will suppress subsequent seedling recruitment. Another effective use of mulch, especially to suppress dense ground covers, combines cardboard and organic mulch. The cardboard covers and overlaps edges of the treatment area, and is then covered with organic mulch. Small drain holes in the cardboard prevent water from pooling. Left to compost in place, the cardboard will suppress vegetation underneath.
Soil solarization uses polyethylene sheeting to cover low growing, cultivated, mowed, or chopped invasive infestations and trap solar energy to heat the soil and space under the sheeting to kill and suppress invasive plants. At least 2 years of summer cover are needed to suppress most invasives plants by 90 percent. Other plants are killed by this method—it is not selective. Black sheeting is more effective than clear sheeting because it blocks needed sunlight, and, at an extra cost, is available with UV blockers to greatly extend the useful life of sheets to more than one growing season. Sheeting costs range from $1,500 to $3,500 per acre, while the labor costs of installation have not been reported. Sheets can be held in place with soil mounds and squares of old carpet. A detriment is the mosquitoes that breed in rainwater puddles that form on sheets. The method is useful as a first treatment for relatively small areas and where herbicides cannot be used. Summer is the most effective season, and use on wet soils increases control. After removal, the bare soil is open for reinvasion unless desirable revegetation is gained.
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