• Topics: Agronomy  | Weeds in Florida (SP 37)  | Leguminosae (Fabaceae) (taxonomic family)  | Weed Management in Cotton  |  Peanut Weeds  |  Ferrell, Jason A  | Hall, David W  | Vandiver, Vernon V 

Hemp Sesbania, Sesbania exaltata (Raf.) Cory¹

Classification

• Common Name: Hemp Sesbania

• Scientific Name: Sesbania exaltata (Raf.) Cory (Sesbania macrocarpa Muhl. may be the correct name for this species.)

• Family: Leguminosae (Fabaceae), Bean Family

Seedling

The stems are thick and smooth with two faint ridges along the upper portion (Figure 1). The cotyledon blades are oblong, thick and smooth, with a midvein that is indistinct near the base on the upper surface but distinct on the lower surface. The petioles are short and flat with smooth ridges across the upper surface. The leaves alternate with the first leaf being simple. All additional leaves are even-pinnately compound with 6-8 or more leaflets. The individual leaflets have very short, minute stalks. The central rachis has a groove on the upper surface. The petiole has 2 stipules. The developing opposite leaflets are initially pressed together.

Figure 1. 

Seedling, Hemp Sesbania (Sesbania exaltata [Raf.] Cory).

Mature Plant

S. exaltata is a robust annual with smooth stems growing to 4 m tall and with few or no branches (Figure 2). The stem tips have few or no hairs. The leaves are alternately arranged and are once even-pinnately compound. The leaves may be as long as 30 cm. Each leaf may have from 20-70 leaflets. The leaflets have smooth margins and are narrowly oblong to linear-elliptic or linear with a point on the tip. The leaflets may be up to 3.5 cm long and 8 mm wide, and are smooth and somewhat waxy beneath. The stipules are not persistent. The flowers occur in the axils of the leaves. The calyx tube is smooth and is from 3-4 cm long. The corolla is 1.5-2.0 cm long. The petals are yellow and are often streaked or spotted with purple. The fruit is a dry, smooth, linear pod from 10-20 cm long and 3-4 mm broad. Each pod contains from 30-40 seeds.

Figure 2. 

Mature plant, Hemp Sesbania (Sesbania exaltata [Raf.] Cory).

History

Sesbania is from the word Sesban which is thought to be the name of an Arabic genus. The Latin word exaltata means tall and refers to the height of the plant. The Latin words macro, large, and carpo, fruit, refer to the long pod.

Habitat

S. exaltata occurs along ditches, roadsides, fields, disturbed sites, river banks and lake shores throughout Florida westward to southern California and northward to New York. It is also found in Central America.

Biology

Hemp Sesbania germinated at temperatures ranging from 15-40°C. Optimal growth occurred from 30-35°C. The seed coats are from 59-63% impermeable. These can be made permeable by acid scarification or mechanical scarification. This results in 98% germination. Increased germination also resulted from an increase in oxygen concentration (from 0 to 100%). Induced moisture stress by osmotic pressure from 0 to -8 bars resulted in a decreased germination from 95% at 0 bars to 21% at -8 bars. After burial 18% of the seeds were still viable after 5½ years.

Control

Peanuts

Hemp sesbania will successfully escape control of most preemergence herbicides. However, preemergence applications of Valor will provide approximately 80% control. Paraquat plus Storm, at cracking, is a highly effective option while paraquat alone or with Basagran will not provide satisfactory control. Postemergence, Ultra Blazer is an excellent option and will deliver very high levels of control. Other commonly used postemergence herbicides are largely ineffective against hemp sesbania.

Cotton

Hemp sesbania is a difficult weed to control since it will successfully escape control of most preemergence and postemergence herbicides. The only truly effective herbicides are glyphosate and Staple applied postemergence. Most postdirected herbicides are also not highly effective on this weed. Therefore, timely applications of glyphosate are very important.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.

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