Culture and Use of Black Locust

Abstract

Robinia L. (locust) species are among the most widely planted tree species in the world because they are ornamentally attractive, drought tolerant, fast growing, fix nitrogen, have very hard durable wood, and are adaptable to many sites and climates. Recent taxonomic analysis indicates there are four species, black locust (R. pseudoacacia L.); bristly locust (R. hispida L.); clammy locust (R. viscosa Vent.); and new mexican locust (R. neomexicana A. Gray). All four species originate in the southern United States and northern Mexico. Many horticultural cultivars are available. Locusts are tolerant of a wide range of soil types so long as there is good drainage, adequate moisture, and it is not very clayey. The environmental tolerance of locust makes it an excellent candidate for horticultural uses and for future breeding and selection to enhance its many desirable traits. It is easy to propagate via seed, root cuttings, soft- or hardwood cuttings, budding/grafting, or tissue culture. Locust has indeterminate growth. Spacing of plants in plantations is critical for the production of multiple products including high value timber. Locust is known for its ability to withstand drought conditions however at the cost of leaf shedding. Black locust contributes high levels of nitrogen to the soil from nitrogen fixing bacterial symbiosis. The major drawback to large-scale production of black locust in its native range is the damage that occurs from the locust borer (Megacyllene robiniae Forster). When planted outside the range of the locust borer it can be grown successfully as landscape specimen trees and as trees large enough for lumber production when varieties with straight trunks are grown. Damage from locust leaf miner (Odontata dorsalis Thunberg) can greatly detract from the trees ornamental qualities. Its most common use is as a site reclamation species. The tree is also used in honey production. The wood is highly decay resistant and is greatly valued for poles and posts. The wood is extremely hard and easy to work making it highly desirable for many construction uses.