- Pest Type: Weed
- Crops Affected: Wheat, Cotton, Potatoes, Soybeans, Corn
- Scientific Name: Cenchrus incertus
- Pest Order: Poaceae
Field sandbur is a coarse-textured, light green, clump-forming summer annual with prostrate and ascending tillers (generally 10-50 cm tall), which terminate with a spike of spiny burs.
Reproduction is by seed. The seeds are enclosed in a bur about 10 mm long and 4 mm in diameter. Seeds mature in July to October and germinate in spring and early summer.
New leaves are folded in the bud.
Stems are smooth, branched, and flattened. The leaves are alternate, smooth except for sparse hair on the margin, narrow, and less than 15 cm long. The sheath is loose, and ligules are a fringe of short hair.
Stems are either erect or more often decumbent at the base. The prostrate and ascending branches will root at the nodes and will often form matted patches.
Roots are fibrous, and adventitious roots develop at the lower nodes of tillers.
Flowers bloom in July to September and are on a spike (about 4 or 5 cm long) with 4 to 15 spikelets. Seeds are enclosed in a spiny bur. The bur is rather oval, hairy with straight spines which are triangular at the base and finely barbed. The spike is often exceeded by the terminal leaf blade. The full seed spike is erect or ascending and grows up to 50 cm tall.
The plant becomes desiccated and brittle after frost, but the burs remain sharp, hard, and stick to skin, fur, and clothing. The dry burs also float in water.
Field sandbur prefers dry, sandy sites but also grows on heavy soils. This weed can be found in cultivated fields, pastures, waste areas, roadsides, gardens, and lawns. The burs are a discomfort to man and animals, and they lower the quality of hay.
This weed can be found across the United States, especially in the southern half.
Seedlings of foxtails and fall panicum look somewhat similar, but the seedlings of field sandbur have folded leaves in the bud, whereas the others are rolled. Longspine sandbur is very similar to field sandbur, but the burs of longspine sandbur are burs are more rounded to egg-shaped and larger.