For larger areas, control of Miscanthus is possible using chemical or mechanical means. Ideal control measures include the following steps:
- In late winter or early spring, before new growth starts, remove previous year's growth by cutting (or burning, see below) the entire plant back to the ground. If possible, remove the clippings and all previous year's growth.
- This removal ensures vigorous new growth, and the lack of any dead leaves or culms creates ideal conditions for the use of chemical control.
- When new growth is 12" tall, in mid-spring or early summer, spray all green tissue with glyphosate. Allow the plant to die and, when completely brown, cut the dead foliage back to the ground. NOTE: If it is not feasible to remove the previous year's growth, as indicated in step 1, wait until plants are 12-24" tall, usually early to mid-summer, to proceed with spraying. Coverage will be hampered by standing dead culms from the previous year.
- If necessary, spray regrowth again in late summer or early fall, when growth is 12", with glyphosate.
- Repeat the process the following year, if necessary.
Chemical spraying of the cut surfaces after cutting plants back (often recommended for controlling woody plants) is NOT an effective way to control Miscanthus. An adequate amount (12-24") of actively growing green foliage should be present for good chemical control.
Repeated mowing, as short as possible throughout the growing season, will kill Miscanthus, usually in 2 seasons. But areas where there is a seed bank may require several years of mowing. At least 2 mowings per year should be done, ideally monthly, or mowing management similar to that needed for lawn or turfgrass care, will provide the best control.Miscanthus cannot tolerate repeated mowing or cutting back DURING THE GROWING SEASON. Cutting the plants back in late winter or when dormant will provide NO control and can actually enhance growth if the cuttings are removed, similar to haying.
Removal of Individual Plants or Hand Digging
Individual plants can be removed by digging, and for small areas this is a very practical and easy method. Plants can be removed any time of the year. Removal before flowering assures that fewer seeds are spread into the area. Removal of flowers prior to seed formation is also helpful in controlling the spread of plants in small areas.
BURNING, especially in late fall or winter, WILL INCREASE MISCANTHUS GROWTH, VIGOR, AND SEEDSET.
BURNING SHOULD ONLY BE DONE AS A MANAGEMENT PRACTICE WHEN IT CAN BE FOLLOWED BY CHEMICAL CONTROL.
Burning in late winter or early spring will remove all of the previous year's growth, plants will regrow with increased vigor and if allowed to flower, the seed set can actually be enhanced after burning. Burning, however, can clean an area, so that all foliage will be green and actively growing for effective and efficient chemical control.
Cattle prefer Miscanthus and in Japan it is controlled in fields by allowing cattle to graze beginning in June. Heavy grazing is a known method in Japan for controlling Miscanthus. Goats, sheep and horses will also eat Miscanthus. Most North American wildlife, including deer, will not eat Miscanthus, it is of little value to wildlife as food.