Research programs to improve forage production for the southern livestock industry have been in progress across the region for more than a century. The characteristic infertile soils and associated low quality, summer-growing grasses indicate potential for substantial benefit from the perennial warm-season legume plant functional group. Considering the tremendous number of warm-season or summer-growing legumes described in the taxonomic literature, rate of success in development of existing species for use as commercially propagated forage plants is extremely low. This plant group includes a tremendous range in growth forms from trees and vines to herbs. An extensive range in primary propagation mechanisms from primarily climbing viney spread to obligate seed multiplication is represented. These wide ranges are included among the few species of value or potential value for forage and among those considered invasive. The potential for invasiveness is closely associated with success as a forage plant due to similar requirements for high levels of success in the two roles. Conversion of almost the entire southern landscape to agricultural uses early in the last century left little recognizable need to consider potential escape of crop plants. Kudzu presents a rather drastic illustration of unintended and unexpected consequences, with no real solution readily apparent. Control efforts must be made, but these must be more strategically based than many past unsuccessful efforts. In many situations, use of grazing animals appears to provide a cost-effective component for a control strategy. Control of kudzu in commercial forests, natural areas, and urban landscapes must be addressed.
The additional perennial warm-season legumes potentially useful as forage plants must be considered in light of the unexpected results from kudzu. Sericea lespedeza can become a problem within the landscapes where it is now used as a forage and conservation plant. Effective strategies for dealing with the existing problem of unwanted stands and preventing future similar situations are needed. The limited available resources for control of plant pest problems in either commercial or non-commercial situations demand that priorities be set and only the highest priority plant invasion problems fully addressed. As with kudzu, some level of reduced-cost limitation of continuing spread of both sericea lespedeza and mimosa in localized situations should be attainable with strategic grazing perhaps selecting species of grazing animal according to the plant community involved. Cattle as generalist grazers may be less desirable where grasses are to be provided competitive advantage. Goats typically browse woody species in preference to grasses, while sheep can be used to some extent to target forb species over grasses and woody plants. Current information indicates that planning, timing of interventions, monitoring, and planned follow-up over periods of several years will be required to control existing undesired populations of the perennial legumes kudzu, sericea lespedeza, and mimosa. In some situations, ecological processes over extended time may be key components of economical control strategies. Also, more emphasis on developing the potential forage resources provided by native species of this plant functional group, rather than primary emphasis on introduction of novel species, appears appropriate.
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