Upright perennial grass, reproducing by large rhizomes and seeds. Well adapted to hold its own in competition with crop plants. Stems up to 6 to 8 feet high or more, from a freely branching, stout, rhizome-possessing, fibrous root system. Leaves alternate, simple, relatively wide and long. Spikelets 1-flowered, in groups of 3, in rather open large panicles. Fruit a caryopsis or grain, finely striate, reddish-brown. Flowers from May till frost and seed to frost.
Prevention of Spread of Johnsongrass
New infestations of Johnsongrass may be reduced by planting Johnsongrass free seed, using livestock feed that is free of Johnsongrass seed and cleaning machinery before leaving infested fields.
Johnsongrass Control Practices
Control of Johnsongrass shall mean preventing the production of viable seed and destroying the plant's ability to reproduce by vegetative means.
Procedures to be used to control Johnsongrass shall include cultural control practices and chemical control or a combination of these two controls.
Cultural Control Practices
Cultivation may begin any time during the growing season and shall be done in such a manner as to cut off the entire plant at each operation (use a duckfoot or blade type implement). Cultivations shall be 3 to 5 inches deep at intervals of 14 to 18 days. When the plants have been so weakened that they emerge more slowly, the cultivation intervals may be extended to such time as will permit the plants to grow not more than 10 days after each emergence of first plants, but not to exceed intervals of 3 weeks.
Cultivation shall be continued until the plants have been eradicated or have been suppressed to such extent that remaining plants may be more economically destroyed by the application of approved chemicals to individual plants or by hand cultivation.
In yards, flower gardens, lawns and among trees and shrubbery, hoeing and other effective means of thoroughly cutting the Johnsongrass at regular intervals, not to exceed 14 days during the growing season, shall be construed as intensive cultivation.
A combination of small grains and intensive cultivation may be used. Close grazing or mowing at 2 or 3 week intervals through the growing season and followed by late fall plowing, to expose the root stalks through the winter, is an accepted control practice.
Herbicides Approved for Controlling Johnsongrass
The following herbicides may be used for cost-share with landowners. Other products labeled and registered for use on this noxious weed in Kansas may be used in accordance with label directions but are not available for cost-share. Be sure to follow all label directions and precautions. For additional information consult the current KSU publication of "Chemical Weed Control for Field Crops, Pastures, Rangeland, and Noncropland".
- Bromacil (Hyvar). Do not apply to cropland. Use for industrial sites and noncrop areas. Apply before or during active plant growth. Follow label directions and precautions.
- Glyphosate (Roundup). For best results apply to actively growing plants when most have reached boot to head stages of growth. Do not apply after the plants turn brown in the fall. Allow 7 or more days between application and tillage. Always follow label directions and precautions.
- Sulfometuron (Oust + nonionic surfactant). Do not apply to cropland. Apply preemergence or early post emergence to boot stage. Follow label directions and precautions.
- Trifluralin (Treflan). Apply Treflan at the 2x rate. Follow label directions and precautions.
- Fluazifop-P-butyl (Fusilade). Follow label directions and precautions.
- Sethoxydim (Poast, Poast Plus). Follow label directions and precautions.
- Fluazifop-P-butyl + Fenoxaprop-ethyl (Horizon 2000, Fusion). Follow label directions and precautions.
- Primisulfuron (Beacon) Follow label directions and precautions.
- Nicosulfuron (Accent) Follow label directions and precautions.
- Imazapic (Plateau) Follow label directions and precautions.
- Quizalofop (Assure) Follow label directions and precautions.
- Sulfosulfuron (Outrider) Follow label directions and precautions.
- Imazapic + Glyphosate (Journey) Apply to Johnsongrass when it has reached 18-24 inches in height at the whorl. Follow label directions and precautions.
- Nicosulfuron + Rimsulfuron (Steadfast) Follow label directions and precautions.
- Foramsulfuron (Option) Follow label directions and precautions.
There are no biological controls approved for Johnsongrass at this time.