Chitalpa frozen back, now growing

We have two chitalpa trees. We had a harsh winter in Sparks, NV last year. One tree survived and is beautiful. The survivor is over 8 ft. tall. The other one never recovered. We waited until the end of June to decide whether to replace it, but then it started getting shoots around the base of the tree at ground level. I was not sure if these were just suckers or good growth, so I let it go. The branches grew to over 6 ft., but the leaves were very large and reminded me of suckers. Some smaller branches started coming out from the new branches, and they look more natural. We have now cut back the branches with the larger (sucker?) leaves. It looks scrawny, but I hate to take it out. Do you think it will survive the next winter and come back?

Your problem sounds interesting and challenging, and your environment in Sparks is similar to parts of New Mexico (USDA hardiness zone 7) where we also grow chitalpa.

Were the two chitalpa trees near each other, or was one in a more protected location (less wind, less cold, more water)? It is strange for one to survive and one to be severely injured unless there was a difference in exposure. There may have been other problems, such as poor establishment (poor root development) in the injured tree. It is also possible that there was some genetic difference. (There are two cultivars of chitalpa, so you may have had one more sensitive than the other.) Finally, there is the possibility of what you suspect, that it was otherwise healthy and suffered winter damage. Since one survived and the other didn't, we need to at least consider the difference between the two trees. All these possibilities are reasons your problem is challenging.

The regrowth you described is not unusual. New growth after injury may look somewhat different. This is not a problem unless the new growth developed below a graft union and was a rootstock catalpa rather than chitalpa. However, the subsequent development of growth more characteristic of chitalpa suggests that the initial growth was atypical because the regrowth was extremely vigorous (the whole root system supported only this new growth). If the leaves became very broad (catalpa-like) and all subsequent growth was the same, you should probably remove the tree, but since the leaves are more chitalpa-like now, let it grow.

Regarding its chances of surviving next winter - survival depends on how harsh the winter will be and if it is in a more exposed location than the other tree. It will be interesting to observe and try to determine the cause of the problem. I would not remove it.

If you need more information, you can get information from your local Cooperative Extension Service office. The Extension Agent there will be familiar with your environmental conditions and the responses of plants under your conditions. The agent will have observed the responses of other trees in your community and can very capably address the situation that resulted in injury to your tree.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

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