Grazing for Control of Himalayan Blackberry
(Rubus discolor)
Contrary to its common name, Himalayan blackberry is a native of western Europe. Himalayan blackberry was probably first introduced to North America in 1885 as a cultivated crop. By 1945 Himalayan blackberry had become naturalized along the West Coast. Himalayan blackberry occurs mainly in areas with an average rainfall greater than 76 cm, at altitudes up to 1800 m. and on both acidic and alkaline soils. Himalayan blackberry tends to prefer wet sites even in relatively wet climates.
Studies done on prescribed grazing of Himalayan blackberry in Australia indicate the following: In an ungrazed area, 96% of the plants produced daughter plants; in areas grazed lightly by horses the number dropped to 11%; in areas grazed by cattle only 1% of all plants had daughter plants; and no plants had daughter plants in areas grazed by sheep.
In New Zealand the recognized method of blackberry control in the past has been the farming of large numbers of goats. This method had been effective in preventing canes from totally covering large areas. Blackberry is readily eaten by goats throughout the year, even when their is an abundant supply of pasture and other plants. In many areas of California the use of Angora and Spanish goats is showing promise as an effective control for Himalayan blackberry. In Cleveland National Forest goats are herded for firebreak management of brush species on over 79,000 acres of land. Goats are less costly to utilize than mechanical and chemical control methods. They can negotiate slopes too steep to mange with machines and do not pose the environmental dangers inherent with herbicides.
Sheep are more selective than goats in their food choices by function well in grazing down a variety of plants. Thus sheep grazing may be a practical alternative to mowing. It is important to properly manage sheep grazing due to soil compaction
if sheep are allowed to graze wet areas.
Chickens, surprisingly enough, are known to effectively digest (and destroy) all weed seeds passing through their crops and can thoroughly graze back vegetation in areas of up to one acre in size. Releasing chickens into an area after the mature plants are removed allows them to scratch and peck out weed seeds and potentially reduce the weed seed bank into the soil.
