Common Locust trees in our area:

 

 

Honeylocust:

 

• Broadleaf deciduous tree, 30-70 ft (9-21 m), open, spreading crown, produces light airy shade, few if any spines (thorns) on the trunk or branches.  Stems shining, smooth, and reddish to greenish-brown, distinctive zigzag form with enlarged nodes (appear as spur shoots); no terminal winter bud, about 5 small lateral buds at a node, more or distinct, some hidden below the bark.  Leaves alternate, pinnately or bipinnately compound, 15-20 cm long, pubescent rachis, leaflets only 2.5-4 cm long.  Flowers greenish-white, fruit are brown pods, 18-20 cm x 2.5 cm.  Some cultivars are fruitless.

 

• Sun.  Readily transplanted.  Withstands a wide range of conditions, i.e., drought, high pH, salt.  A good desert tree, but develops best on rich, moist bottomlands, or on soil of limestone origin.

 

• The honeylocust pod gall midge (Dasineura gleditchiae) deforms leaves in some areas, causing loss of ornamental value i.e., death of small branches.

 

• Hardy to USDA Zone 3    Species (Gleditsia triacanthos) native range from southwestern Ontario, Pennsylvania to Nebraska, south to Florida and Mississippi.

 

 

 

 

 

  Black Locust:

 

• Deciduous tree, 30-50(80) ft [9-15(24) m], upright habit, bark reddish brown to almost black, deeply furrowed.  Stems zig-zag, often spiny, with paired stipular prickles at nodes, these are more prominent on vigorous shoots and suckers.  Terminal buds absent.  Leaves alternate, compound (odd-pinnate), 15-35 cm long, with 7-19 opposite leaflets, each 2.5-5 cm long, elliptic or ovate, bluish green.  Flowers white, 2.5 cm pea-type, in 10-20 cm long racemes, fragrant.  Fruit pod-like, flat, brown-black 5-10 cm long, mature in Oct.

 

• Sun, will grow in about any soil except permanently wet.  Dirr (p. 754) calls it an "alley cat" type tree which can survive under the toughest conditions.  Bees produce a delicious honey from the flowers.   Twigs and bark are poisonous to domestic livestock.

 

• Hardy to USDA Zone 3      Native from Pennsylvania to Georgia, west to Iowa, Missouri, and Oklahoma.

 

 

 

 

Common problems with Locust trees:

 

 

Insects:

 

Aphids	Honeylocust Plant Bugs	Honeylocust Spider Mites	Locust Borer
Aphids feed by sucking up plant juices through a food channel in their beaks. At the same time, they inject saliva into the host. Light infestations are usually not harmful to plants, but higher infestations may result in leaf curl, wilting, stunting of shoot growth, and delay in production of flowers and fruit, as well as a general decline in plant vigor. Some aphids are also important vectors of plant diseases, transmitting pathogens in the feeding process. A sticky glaze of honeydew may collect on lower leaves, outdoor furniture, cars, and other objects below aphid feeding sites. Honeydew coated objects soon become covered by one or more brown fungi known as sooty molds. Crusts of sooty mold are unsightly on man-made objects, and they can interfere with photosynthesis in leaves. MORE INFO	Nymphs feed on the developing buds and leaves. They use a “lacerate and flush” feeding style that produces a lot of injury to the feeding site. Young leaves and buds are often killed. Older leaves may survive but show discoloration and deformation of developing foliage due to localized necrosis around feeding points. Heavy infestations may greatly retard foliage development  in spring and have been associated with twig and branch dieback. During outbreaks many of the pale-green nymphs may be dislodged from trees following light shaking of foliage. This can result in nuisance problems when they land on people.   MORE INFO	This native pest overwinters as red colored females on the bark of host trees. Eggs start hatching soon after honeylocust budbreak, followed by many generations until early fall. Mites develop slowly in cool weather, but in very hot conditions, one generation can pass in 4 days, which is why a tree can seem to suddenly fill with mites. Feeding damage is the typical spider mite stippling on the leaf surface, and when severe, leaflets will turn yellow and drop prematurely. The honeylocust spider mites will not kill the tree. Trees that are water-stressed are more likely to be attacked, so make sure trees get optimal water. Look for mites by turning leaves over and watching for small, slow-moving bodies near the base of the leaflets. You may also notice small black dots of frass. MORE INFO
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Diseases:

 

Wetwood (slime flux)
Bacterial wetwood, also called slime flux, is a major bole rot of trunk and branches of trees. Slime flux has been attributed to bacterial infection in the inner sapwood and outer heartwood area of the tree. A tree with slime flux is water-soaked and "weeps" from visible wounds and even from healthy looking bark. The "weeping" may be a good thing as it is having a slow, natural draining effect on a bacterium that needs a dark, damp environment. A tree with this bole rot is trying its best to compartmentalize the damage. MORE INFO
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