Chitalpa: Fabulous but Flawed

Chitalpa is a fast-growing ornamental tree with showy flowers… and a serious, ubiquitous problem. Here’s everything you need to know to help you decide whether you should plant this tree and how to care for an existing one.

East meets west in chitalpa (X Chitalpa tashkentensis), a small, deciduous ornamental tree. It’s a hybrid cross of desert willow (Chilopsis linearis), a Sonoran Desert native, and catalpa (Catalpa bignonioides), a native of southeastern states.

There is nothing subtle about this tree. It grows fast and rangy. Its leaves are big and so are its flowers. It sheds both throughout the growing season, never letting you forget its presence.

From spring through fall, it’s covered with orchid-like flowers ranging from white to pink. When in bloom, they attract butterflies, bees, and hummingbirds.

Why I Like This Plant

• Exceptionally attractive tree
• Large orchid-like flowers
• Fast-growing for quick shade and color
• Attracts hummingbirds, butterflies, bees
• No thorns, non-allergenic, non-toxic

Things to Watch Out For

While chitalpa clearly has many attributes, it has equally many downsides, including one that is quite serious.

• This is a messy tree. It constantly drops decent-sized leaves and flowers spring through fall.
• It naturally grows as a large sprawling shrub that sends up a lot of suckers, so it takes frequent pruning to keep it tree-shaped.
• It’s often a short-lived tree. They are prone to many kinds of infestations — insect and bacterial — including one that is ubiquitous and inevitably fatal.

Optimal Growing Conditions

Here are the key factors to keep in mind when growing a chitalpa.

Temperature

Chitalpa should be grown in USDA Hardiness Zones 6 – 11. It is very cold-hardy and can survive temperatures down to 10℉, but reportedly can freeze back to the ground when grown in zone 6.

Sun Exposure

Chitalpa likes full sun but tolerates partial shade. However, its trunk is prone to sunscald in hotter areas like Phoenix. Letting it grow as a shrub instead of pruning it as a tree can help.

Size and Growth Rate

Chitalpa is a fast grower that quickly reaches a size of 25’ high by 25’ wide. Unlike many fast-growing trees, it is surprisingly wind-resistant. Its soft wood bends with the wind rather than breaking.

There are many chitalpas in my neighborhood and I’ve watched them grow like crazy. Some that were as tall as me two years ago are now taller than a house!

However, this fast growth is not all good, sometimes causing cracks in the trunk’s bark.

Soil

Chitalpa is not particular about soil as long as it’s well-drained. Like its parent plant, desert willow, it’s tolerant of alkaline soils.

Pests & Diseases

Unfortunately, this lovely tree has a long list of pests and diseases. It is commonly infested with these insects:

• aphids
• hornworms
• mealybugs
• scale
• thrips
• whiteflies

But the biggest concern by far is Xylella fastidiosa, a fatal bacterial infection that makes it hard for a plant to transport water to the leaves. This disease is sometimes referred to as Chitalpa leaf scorch. Signs of an infected tree are:

• chlorosis
• leaf scorch and spotting
• small leaves, thin canopy
• branch dieback

And the news gets even worse…

Since chitalpa is a sterile hybrid, all trees are propagated by cuttings.
Research has found that virtually all chitalpas are infected with Xylella fastidiosa.
For this reason, I would not recommend planting this tree.

There is no cure for this bacterial infection, but you can slow a tree’s demise by giving it adequate water and fertilizer, and removing dead and dying branches.

If you’re concerned about your chitalpa and want to know more, see New Mexico State University’s fact sheet “Bacterial Leaf Scorch of Chitalpa.”

Chitalpa:
The Essentials

Common Name	Chitalpa
Scientific Name	X Chitalpa tashkentensis
Origin	Sonoran Desert/ Gulf Coast hybrid
Plant Type	Deciduous tree
USDA Zones	Zones 6 – 11
Cold Hardiness	To 10℉
Flower Color	White to pink
Flower Season	Spring, summer, fall
Mature Size	25’ high x 25’ wide
Growth Rate	Fast
Sun Tolerance	Full, part sun
Water Needs	Moderate
Pests & Diseases	Root rot, sunscald Various infestations
Garden Friendly	No thorns, non-toxic, non-allergenic
Wildlife	Attracts butterflies, hummingbirds, bees

How to Care for Chitalpa

Whether you’ve recently planted a new chitalpa or have an existing one in your yard, here’s how to take care of it to keep it healthy and looking its best.

How to Water

Unlike desert willows, which are low water use desert natives, chitalpas need a moderate amount of water.

There are two factors to consider when watering any desert tree.

• First is how often to water. This will vary with the seasons.
• Second is how much water to give your tree with each watering. This depends on its current size.

To determine the ideal watering schedule for any desert tree, you’ll find everything you need to know, including easy-to-use charts, at How to Water Desert Trees: How Often? How Much?

Should You Fertilize?

Since chitalpa is a non-native and a heavy bloomer, it can benefit from fertilizer in the spring. Feeding also helps minimize the impact of Xylella fastidiosa.

How to Prune

Chitalpas are multi-branched and naturally grow more like a shrub than a tree. A chitalpa can be shaped into a multi-trunk tree (preferred) or even trained to grow as a more conventional single-trunk “lollipop” tree (not recommended), but it will require regular selective pruning.

Chitalpa trees perpetually try to revert to their natural shrub-like form and will put out new suckers at the base. Pruning these is a straightforward task you can do whenever they appear.

Chitalpa Cultivars

Chitalpa has a few cultivars that differ mainly by flower color.

Chitalpa tashkintensis ‘Morning Cloud’ has pale white flowers with purple throats.

Chitalpa tashkintensis ‘Pink Dawn’ has pale lavender-pink flowers with pale yellow throats.

Chitalpa Myths Busted

Chitalpa is often touted as “hailing from the mountainous regions of Central Asia” but this is not true. While it was bred in Uzbekistan by a Soviet geneticist, both of the parent plants — desert willow (a Sonoran Desert native) and catalpa (a Gulf Coast native) — are as American as apple pie.

Another common piece of misinformation is that chitalpas have a life expectancy of 150 years. (Maybe the parent plants can, but not this hybrid.) Considering they were first bred in 1964, this can’t be known for another 100 years! Unless a cure is found for their inherent disease, these trees will continue to be relatively short-lived.

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Photo Credit

Frau Siebenschläfer, CC BY-SA 3.0, Wikimedia Commons