   Honeylocust - February 1, 2006 Jeff Schalau, County Director, Associate Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Selecting the right tree species for your particular needs is not always easy. Aside from appearance, you should also consider space requirements, evergreen vs. deciduous, insect and disease susceptibility, and irrigation requirements. The honeylocust (Gleditsia triacanthos) is an excellent deciduous tree for both commercial and residential plantings across Arizona (suitable for USDA Plant Hardiness Zones 3-9). It has few pests, an interesting branching pattern, tolerates our summer heat, and has moderate irrigation requirements. Honeylocust is native to the eastern U.S. from eastern Texas north to South Dakota east to Pennsylvania and back south roughly following the Appalachian Mountains then south to Mississippi and Louisiana. Over its native range, it seldom grows in pure stands and tends to prefer the river valleys and floodplains. Even though it’s from the humid eastern U.S., it performs well in Arizona. Honeylocust is a member of the pea/bean (Leguminosae) family. It produced seeds in long, flat, twisted pods. The seeds have impermeable coats and do not readily germinate until the seed coat has been mechanically broken or it has passed through the gut of an animal. This is true for many seeds in this family: mesquite, palo verde, catclaw, lupine, etc. Native grown honeylocust saplings produce woody spines which are undesirable in landscape situations. As these trees mature, they tend to produce fewer spines. However, when cuttings are grown from thorn-less portions of mature trees they tend to remain thornless. The nursery industry has used this to produce honeylocust cultivars that have no thorns and have desirable growth forms and/or interesting foliage colors. These are grown from vegetative cuttings or are grafted onto seedling rootstock. Every once in a while you may see a mature honeylocust tree with spines. These individuals were probably grown from seed. Honey locusts are adapted to salty and/or alkaline soils making them a good choice for arid areas. Once mature, they have a lacey canopy which provides good visibility through the canopy and grass can grow right up to the trunk. The sweet smelling flowers are much favored by bees and the juicy pulp between the seeds within the pods is relished by cattle and wildlife. The wood is very hard, very heavy, and resistant to decay. It is used occasionally for furniture, fence posts and railroad ties. Because Arizona is outside of honeylocust’s native range, there are relatively few pest management issues. Honeylocust bark is gray and relatively thin. This makes them susceptible to fire scorching. While you may not care about fire in your yard, this fire susceptibility is probably what prevented honeylocusts from growing on the North American prairie. The following are a few of the most popular varieties (cultivars) of honeylocust: ‘Moraine’ is thornless and fruitless, has a broad graceful form, dark green leaves, and golden yellow fall color. ‘Shademaster’ has ascending (downward sloping) branches, dark green leaves, is almost fruitless, and is a strong grower. ‘Sunburst’ is broadly pyramidal, has golden yellow new leaves that mature to bright green, and is fruitless. ‘Summer Lace’ is vigorous and graceful, has light green leaves that mature to dark green, with a broad rounded canopy. ‘Ruby Lace’ has red new leaves that turn purplish bronze maturing to green in summer, many people feel that this is not the best honeylocust. For other tree ideas, get yourself a copy of the University of Arizona publication titled Drought Tolerant Trees for Mid-elevation Deserts (3,000 to 4,000 ft). It is available in our offices and on-line at: ag.arizona.edu/pubs/garden/az1239.pdf. The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at mgardener@verdeonline.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/. |