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Wednesday - July 02, 2014

From: Pewaukee, WI
Region: Midwest
Topic: Diseases and Disorders, Pruning, Trees
Title: Northern Catalpa Tree Doing Poorly
Answered by: Anne Van Nest

QUESTION:

One of our Northern Catalpa trees appears to be dying. It is about 28 feet tall and this year only about 1/3 of it is producing leaves. It is next to our largest Catalpa tree (about 65 feet tall and about 25 feet apart) and that tree looks perfect, as it always does. We had a very rough winter here is Wisconsin. Could the winter have affected one tree and not the other? Is there any way to save the smaller one with careful pruning? Thanks for any help or insight.

ANSWER:

Northern catalpa (Catalpa speciosa) is a distinctive tree with large heart-shaped leaves and showy white bell-shaped flowers in large clusters at the ends of the branches. Each bloom has yellow streaks and purple spots inside. The fruit is a long narrow bean-like pod that grows up to 18 inches long and persists into the winter.
Since your younger catalpa is in the same location as an older and bigger catalpa, the soil, moisture, sun and environmental conditions should be favorable for it. Catalpa are not usually extremely long lived though. This is the case with many fast-growing trees. So the younger tree may not have longevity in its genes. Catalpa are also not particularly drought tolerant. Perhaps the younger one is now suffering the effects from a past drought.
Northern catalpa are hardy to zone 4 which includes most of Wisconsin (except some of Douglas, Burnett, Washburn, Sawyer and Price counties), so it should be fine with temperatures down to -30 F.
The Missouri Botanical Garden Plant Finder has more information about Northern catalpa if you visit their website. Ultimately, a certified arborist can advise you about the health of your tree. There are some rare but serious diseases that could attack catalpa such as verticillium wilt that could cause a rapid and fast decline as well.

From the Image Gallery

Northern catalpa
Catalpa speciosa