Sesbania exaltata is variously termed Sesbania, Colorado River hemp, hemp, hemp sesbania, and peatree (Duke, 1981).

The genus Sesbania comprises several species of agricultural value, including Sesbania bispinosa (Jacq.) W.F. Wight (Duke, 1981; Miller et al., 1989) which is often called by its former name, S. aculeata (Yost and Evans, 1988), Sesbania rostrata, Sesbania sesban, and Sesbania exaltata (Raf.) Rydb. (Duke, 1981). The latter species is termed Sesbania exaltata (Rafinesque-Schmaltz) Cory by Munz (1973).

This treatment will be principally confined to the latter.

Seed is of variable hardness; scarification is needed for complete germination (Yost and Evans, 1988).

As reported by Duke (1981), sesbania is a perennial semiwoody herb, except where frost-killed yearly, and it behaves as an annual. Plant is 0.4-4 m in height, stems striate and glabrous. Leaves pinnate and 10 cm long or less, bright green, elongate. 20-80 leaflets per leaf, linear-oblong, 1-3 cm in length, pale green, villous below. Flowers yellow with purple or brown spots or streaks, presented in axillary racemes with few flowers.

Sesbania is easily killed by frost and tolerates an annual mean temperature of 12.5-27.8 degrees C, with the mean of 12 cases being 13.1 (Duke, 1981). It should be established during late spring or during summer (Bugg, pers. comm.).

Sesbania is from the North American Center of Diversity and is native to coastal parts of the United States, including southern California, Arizona, and the Southeast. It ranges from the Warm Temperate Moist through Tropical Dry Forest Life Zone (Duke, 1981).

In general, it is adapted to warm lowland tropical and subtropical areas (Yost and Evans, 1988). It does best with high temperatures, low relative humidities, and moist soils, growing exceptionally well in the Southwest where these conditions are met.

It tolerates higher altitudes than crotalaria (McLeod, 1982). In California, it occurs in overflow lands and along ditches in Alkali Sink, Imperial County, eastern Riverside County, and in La Verne, Los Angeles County. It also ranges to the Atlantic Coast and Central America (Munz, 1973).

Duke (1981) stated that sesbania tolerates mean annual precipitation of 6.2-23.2 dm, with a mean of 12 cases of 13.1, and that it does best on moist soils. Yost and Evans (1988) indicated that sesbania does best with moderate to abundant rainfall but tolerates drought once established. They further mentioned that it can be used in semiarid areas, germinating with seasonal rains and maturing during dry periods; it tolerates soil waterlogging and flooding. Sesbania requires more water than other summer legumes, such as crotalaria or cowpea, but also tolerates waterlogged soils better (Miller et al., 1989).

In wildlife plantings, sesbania is sown "with ample fertilizer" and equal parts of browntop millet, proso or hog millet, and beggarweed (Duke, 1981).

Bugg and Dutcher (1993) grew sesbania in combination with other warm-season cover crops in pecan orchards. Satisfactory stands were obtained with the following per ha fertilization rates: in orchard #1, 11.51 kg/ha of P205 (N:P:K 0-46-0) and 1.92 kg/ha K20 (0-0-60); in orchard #2, 14.77 kg/ha P205 and 2.46kg/ha K20; in orchard #3, 11.92 kg P205 and 1.99 kg/ha K20.

Sesbania tolerates soil pH of from 4.5-7.2, with the mean of 10 cases being 6.2 (Duke, 1981). It is said to tolerate alkalinity (Yost and Evans, 1988).

Sesbania can tolerate heavy, waterlogged soils (Yost and Evans, 1988; Miller et al., 1989) and flooding (Yost and Evans, 1988). It purportedly will grow on any soil, including those that are infertile, and has a low lime requirement; best growth is on rich loams (McLeod, 1982).

When planted in a mature pecan orchards in Georgia, sesbania appeared intolerant of shade (R.L. Bugg, pers. comm.).

Sesbania tolerates salinity (McLeod, 1982; Yost and Evans. 1988) and has been used as a green manure for reclaiming saline soils in India, often in conjunction with gypsum (Yost and Evans, 1988).

Sesbania has been characterized as a perennial woody shrub, but an annual at high latitudes (Duke, 1981). Munz (1973) terms it an annual in California. In U.S. agriculture, it is treated mainly as a summer annual legume (McLeod, 1982), and it grows rapidly during a 60- to 90-day summer growing period (Miller et al., 1989).

Suggested seeding rates have included 22-28 kg/ha (broadcast) (Duke, 1981), 10-20 lbs/acre (Miller et al., 1989), 20 to 25 lbs/acre (McLeod, 1982), and 20 to 90 kg/ha (Yost and Evans, 1988).

Suggested sowing depth in 3/4 inches (McLeod, 1982), but seed can be broadcast (Duke, 1981).

Sesbania can be established in perennial warm-season sod by herbiciding with glyphosate, the broadcasting the seed and disking to break up sod and incorporate seed (Bugg, pers. comm.).

Sesbania should be established during late spring or during summer (Bugg, pers. comm.).

Specific Rhizobium inoculant is necessary in most situations unless effectively nodulated crops have ben grown previously (Yost and Evans, 1988). Sesbania should receive "Special Culture 1 For Sesbania" (Duke, 1981) ("Sesbania Spec. 1", Nitragin Co., Burton and Martinez, 1980).

Southern Seedsmen's Association (1992) listed 6 suppliers of sesbania seed. Peaceful Valley Farm Supply carries it. (Mark Van Horn, pers. comm.) Seed is available annually, but never in abundance--in 1992 it was unavailable past July 1. (Fred Thomas, pers. comm.)

Sesbania flowers from April to October in the wild (Munz, 1973), but with normal practices in the Sacramento Valley, it blooms from mid-July to October (Bugg,pers. comm.).

Sesbania seeded in May should have matured seed by mid August (Bugg, pers. comm.).

Sesbania produces seeds profusely and can become a weed if not properly managed. Plants should be harvested for seed when about two-thirds of the seed has begun to turn from green or purple to brown (Yost and Evans, 1988).

The seed remains viable for a relatively long time (McLeod, 1982).

The growth habit is erect (Bugg et al., 1989). Sesbania is described by Munz (1973) as a glabrous annual attaining heights of from 10-30 dm. It has stiff tall stems, and can reach 10 feet in height in 60 days of hot summer weather (Miller et al., 1989).

Sesbania is mentioned as attaining heights of 10-30 dm (Munz, 1973), 10 feet (Miller et al., 1989), and 1-4 m (Yost and Evans, 1988).

Sesbania is shallow rooted compared to other summer legumes and may require irrigation until well established (Duke, 1981).

Drought during the seedling stage can be much more damaging than once the plants are larger (Evans and Rotar, 1987).

Can be planted to moisture without subsequent irrigation for three weeks. Extra water was required to initiate germination in trials at Davis, California. (Mark Van Horn, pers. comm.)

One cultivation may be needed to reduce weeds (Duke, 1981).

Sesbania can be mowed using a flail chopper even after the plant is lignified; it is not clear whether the plant tolerates high mowing very well (R.L. Bugg, pers. comm.).

At 60 days, plants will be quite fibrous and incorporation will require chopping beforehand if a fine seed bed is desired after incorporation. (Mark Van Horn, pers. comm.)

Sesbania can be mowed using a flail chopper even after the plant is lignified (R.L. Bugg, pers. comm.).

Sesbania, Cowpea, or Crotalaria juncea can follow crops such as early sweet corn and early processing tomatoes, and precede fall-planted crops such as vegetable brassicas and cereal grains (Miller et al., 1989).

According to Duke (1981), sesbania has been used as a warm-season cover crop in citrus from Florida to southern California, and on irrigated lands is sometimes used in rotation with vegetable crops. The Yuma Indians use the plant to produce a strong, lustrous fiber for making nets and fishing lines.

Sesbania is sometimes used for wildlife enhancement in southern Georgia. Plantings along orchard borders may do double duty by providing habitat to game birds and predatory insects (Bugg and Dutcher, 1989). As a drought-intolerant species, it might be suitable as a summer cover crop in moist, low-lying (pecan) groves or in orchards with solid-set irrigation (Bugg et al., 1991).

When sesbania is used as a green manure, its roots are said to open up subsoil (McLeod, 1982).

Sesbania can be sown in mixtures with browntop millet, proso or hog millet, and beggarweed to provide quail food (Duke, 1981).

According to Miller et al. (1989), the stiff tall stems of sesbania leave a great deal of residue. Phytomass (dry) production is about 1,500 kg/ha (Evans and Rotar, 1987).

N content is about 65 kg/ha (Evans and Rotar, 1987).

Sesbania can be sown in mixtures with browntop millet, proso or hog millet, and beggarweed to provide quail food (Duke, 1981).

The plant can become very tall and lignaceous, so might be expected to inhibit traffic (R.L. Bugg, pers. comm.)

Grown as a summer cover crop in pecan orchards, sesbania often harbors cowpea aphid (Aphis craccivora) and bandedwinged whitefly (Trialeurodes abutilonea), and has associated lady beetles when pecan aphids become depleted (Bugg et al., 1989). When densities of pecan aphids dropped during July or August, whitefly-infested understory stands of sesbania arrested and retained high densities of convergent lady beetle (Hippodamia convergens Guerin-Meneville), and the principally-arboreal Ollavnigrum (Mulsant). Although adult lady beetles were significantly more abundant in cover-cropped than in control understoreys of resident vegetation from early August through mid September, this did not contribute to increased coccinellid densities in the associated pecan trees, nor to reduction of pecan aphids (Bugg and Dutcher, 1989; Bugg and Dutcher, 1993).

Red imported fire ant was abundant in experimental orchard, yet few ants were seen on sesbania, despite the frequent abundance of cowpea aphid. We have often observed ants tending colonies of this aphid on cowpea, but never on sesbania (Bugg and Dutcher, 1989).

Red imported fire ant (Solenopsis invicta) forages for honeydew produced by cowpea aphid (Aphis craccivora) on cowpea and hairy indigo (Indigofera hirsuta) but not on sesbania (Sesbania exaltata), based on a replicated study conducted in Georgia (Kaakeh and Dutcher, 1992). Ethanol and water extractions of sesbania are toxic to S. invicta.

Duke (1981) reported that the following plant-parasitic nematodes have been isolated from sesbania: Belonolaimus longicaudatus, Dolichodorus heterocephalus, Heterodera glycines, H. schachtii, H. trifolii, Meloidogyne arenaria, M. incognita acrita, M. javanica, and Pratylenchus pratensis.

Sting nematode was abundant and caused reduced yields for cool- season vegetables following cover cropping with a sorghum X Sudan grass hybrid or Sesbania exaltata. Rootknot nematode, Meloidogyne incognita, failed to develop high densities on any of the cover crops, but was particularly abundant on vegetables following sesbania and cowpea (Rhoades, 1983).

Sting nematode was abundant and caused reduced yields for cool-season vegetables following cover cropping with Sesbania exaltata (Rhoades, 1983).

Sesbania is not a good weed competitor as a seedling, it can reach 10 feet in height in 60 days of hot summer weather (Miller et al., 1989). When grown in wildlife plantings, sesbania requires at least one cultivation to reduce weeds (Duke, 1981). Bugg and Dutcher (1989) evaluated weediness in various warm-season cover crops grown in a pecan orchard in southern Georgia, and found sesbania to be especially prone to weed invasion.

Seed serves as food for quail and other wildlife during winter and spring (Duke, 1981).