Johnsongrass (Sorghum halapense)
Plant Characteristics: Rhizomatous perennial warm-season grass. Johnsongrass has a very tall ligule and leaves are characterized by a very prominent white midrib. Seed head is a brown open panicle.
Establishment: Johnsongrass is considered a weed in row crops. It has a high drought tolerance. Johnsongrass can be planted in April by broadcasting at rates of 20 to 30 lb/ac or drilling at 10 to 15 lb/ac. Planting depth should be 1/4 to 3/4 inches.
Fertilization: Best adapted to clay loam or sandy soils with a pH of 5 to 7.5. Very responsive to nitrogen applications.
Grazing/Hay Management: The primary use is hay production but can be grazed under good management. Forage production occurs from May to September with yields ranging from 5 to 7 tons/ac. Harvest Johnsongrass at heading boot stage. Rotational grazing is recommended because close continuous will reduce vigor and stand persistence.
Forage Quality: Prussic acid is a problem, along with nitrate poisoning under drought stress and interstitial cystitis.