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Publication #ENH289

 

Catalpa spp.: Catalpa1

Edward F. Gilman and Dennis G. Watson2

Introduction

Catalpa speciosa (Northern Catalpa) grows in a loose oval, 50 feet tall in most urban locations, but occasionally grows to 90 feet. This coarse, large leaved tree spreads 50 feet and tolerates hot, dry weather, but leaves may scorch and some drop from the tree in very dry summers. Catalpa bignonioides (Southern Catalpa) is somewhat smaller reaching about 30 to 40 feet tall, leaves are arranged opposite or in whorls ( speciosa leaves are opposite) and it is native and has some salt tolerance. A sunny exposure and a well-drained, moist, rich soil are preferred for best growth of Catalpa but they will tolerate a range of soils from acid to calcareous. Both trees have a coarse, very open growth habit forming an irregularly-shaped crown. Popular in older gardens and has a moderately-long life (60 years or so), but trunks on large trees often contain rot. Catalpas are very adaptable and they are tough trees, having naturalized in many parts of the south.

Figure 1. 

Middle-aged Catalpa spp.: Catalpa


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General Information

Scientific name: Catalpa spp.
Pronunciation: kuh-TAL-puh species
Common name(s): Catalpa
Family: Bignoniaceae
USDA hardiness zones: 5A through 9A (Fig. 2)
Origin: native to North America
Invasive potential: weedy native
Uses: urban tolerant; reclamation; shade
Availability: somewhat available, may have to go out of the region to find the tree

Figure 2. 

Range


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Description

Height: 50 to 60 feet
Spread: 40 to 50 feet
Crown uniformity: irregular
Crown shape: oval
Crown density: moderate
Growth rate: fast
Texture: coarse

Foliage

Leaf arrangement: opposite/subopposite (Fig. 3)
Leaf type: simple
Leaf margin: entire
Leaf shape: ovate
Leaf venation: pinnate
Leaf type and persistence: deciduous
Leaf blade length: 8 to 12 inches
Leaf color: green
Fall color: yellow
Fall characteristic: not showy

Flower

Flower color: white/cream/gray
Flower characteristics: very showy

Fruit

Fruit shape: elongated
Fruit length: 12 inches or more
Fruit covering: dry or hard
Fruit color: brown
Fruit characteristics: attracts squirrels/mammals; showy; fruit/leaves a litter problem

Trunk and Branches

Trunk/bark/branches: branches droop; not showy; typically one trunk; thorns
Pruning requirement: needed for strong structure
Breakage: resistant
Current year twig color: green, brown
Current year twig thickness: very thick
Wood specific gravity: unknown

Culture

Light requirement: full sun, partial sun or partial shade
Soil tolerances: clay; sand; loam; alkaline; acidic; occasionally wet; well-drained
Drought tolerance: high
Aerosol salt tolerance: moderate

Other

Roots: not a problem
Winter interest: no
Outstanding tree: no
Ozone sensitivity: unknown
Verticillium wilt susceptibility: susceptible
Pest resistance: sensitive to pests/diseases

Figure 3. 

Foliage


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Use and Management

Growth is rapid at first but slows down with age as the crown begins to round out and the tree increases in spread. The main ornamental feature is panicles of white with yellow and purple markings produced in spring and early summer, depending on the particular tree. But leaves fall throughout the summer in USDA hardiness zone 8 making a mess and the tree looks ragged with yellow leaves in late summer. Flowers make somewhat of a slimy mess for a short period when they drop on a sidewalk but are no problem falling into shrubs, groundcovers, or turf. The fruit is a long pod (up to two feet long) resembling a string bean that can be a slight litter problem to some, but it is quite interesting. The tree is useful in areas where quick growth is desired, but there are better, more durable trees available for street and parking lot plantings. Sixty-year-old trees in Williamsburg, Virginia have three to four-foot-diameter trunks and are 40 feet tall. Catalpa often escapes cultivation and invades surrounding woodlands.

Catalpas are planted to attract Catalpa worms, a large caterpillar prized for fish bait because the skin is very tough and the caterpillar is juicy. The caterpillar can be frozen for use as a fish bait at a later time. The caterpillar can defoliate the tree once or twice a year but there appear to be no adverse consequences to the tree.

Catalpa tolerates a wide range of soils, including pH in the 7's, and is moderately drought-tolerant. It is a tough tree suited for planting in large-scale landscapes.

Pests

The larva of the Catalpa sphinx moth can eat large quantities of leaves. The caterpillar is yellow with black markings. The tree is regularly defoliated and often looks terrible by the end of the summer.

Diseases

Anthracnose will cause dead areas on the leaves.

Brown leaf spots caused by several fungi can attack Catalpa. They are rarely serious so no chemical control is suggested.

Powdery mildew causes a white powdery coating on the leaves. When severe, the leaves yellow and fall off.

Catalpa is susceptible to verticillium wilt. Branches die and eventually the entire tree may die. A symptom of verticillium wilt is discoloration of the sapwood but the symptom is hard to find.

During hot, dry seasons the leaves may turn yellow and brown due to scorch, but the tree lives. Little can be done other than watering.

Catalpa may turn chlorotic due to a high soil pH, but the tree does not appear to otherwise suffer from alkaline soil.

Footnotes

1.

This document is ENH289, one of a series of the Environmental Horticulture, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date November 1993. Revised December 2006. Reviewed May 2011. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Edward F. Gilman, professor, Environmental Horticulture Department; Dennis G. Watson, former associate professor, Agricultural Engineering Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, Dean.