Shattercane Sorghum bicolor L. (Moench.)
Life cycle: Annual
Native status: Introduced, native to Africa
Habitat: Crop fields
General description: Erect, ‘corn-like’ plant, up to 8 ft tall. Seedhead is a large, open panicle; large seeds maroon to black at maturity. Base of leaf blade is usually hairy.
Key ID traits: Membranous ligule; glabrous leaves, leaf sheaths often covered with waxy bloom.
Similar species: Johnsongrass has similar growth habit to shattercane, but is perennial and produces rhizomes. Johnsongrass rhizomes are intolerant of Iowa’s winters, thus it is not a significant problem in the state. Sorghum almum is a hybrid of shattercane and Johnsongrass that produces short rhizomes.
Miscellaneous: Shattercane is an off-type of sorghums grown for grain and forage. Name is due to seed dropping from plant prior to harvest. Most infestations first started in fields planted to a cultivated variety of sorghum. Infestations in Iowa have decreased since the mid-1980s due to introduction of effective herbicides and the decrease in planting of grain and forage sorghum in the state. The thiocarbamate herbicides (Eradicane, Sutan+) were widely used in Iowa and Nebraska to control shattercane. After several years of use soil microbes adapted to the herbicides and degraded the herbicide so quickly that the products were rendered ineffective. A similar fate has occurred with atrazine, although the enhanced speed of degradation is not as dramatic as with the thiocarbamates.