Tree didn't leaf-out

I have a fruitless mulberry tree that is approximately 15 years old and has always done well even though the trunk has a bad split in it that has been there since 1991(never knew what caused the split). Anyway, this year the tree budded out but then most of the buds died off, and it has very few leaves on the tree (maybe two or three dozen on the entire tree). I don't know what has happened to it unless when I sprayed for weeds it damaged the tree. If at all possible, I would like to be able to revive it if it is not too late. I have always used a broad leaf weed killer on my yard and it has never caused any damage to the tree before, so I'm not sure what has happened to the tree. Could you please offer any suggestions on how to revive it?

You have described a tree with many problems. First, to address a safety issue if the tree is near your home or the street. Because of the split, it has the potential to fall causing damage or injury. So, first, do you really want to save the tree? It might be wise to have a local tree care professional who has experience in dealing with hazardous trees inspect the tree and make recommendations.

The reason that it has few leaves could be due to many factors. Here in New Mexico this year, my first thought would be of the late freezes which have been common across the state. Freezing weather after the tree has developed leaves, or as the buds are beginning to open, can kill the new buds. The tree has small buds at the base of the other buds as insurance against this occurrence, but it may take some time for these buds to begin to grow. If you see growth developing from these buds, the tree has dealt with the problem itself. However, if freeze injury is the cause, you may find that some of the twigs and branches were injured beyond their ability to recover. Any dead or severely damaged branches should be pruned. Contact your local Cooperative Extension Service Office for information on proper pruning techniques. The symptoms of freeze injury may continue to manifest themselves over a period of several years, so don't be surprised to see continued dieback and weak growth for the next couple of years.

Disease may be the problem. The fact that the trunk is split suggests that fungus problems could be present. This would be best diagnosed by someone onsite. Contact your local Cooperative Extension Service Office or Master Gardeners for help with that.

The herbicides may also be the problem. Even though you have used herbicides for several years, you may have a cumulative effect and interaction with the other problems mentioned above. Have you been seeing misshapen leaves on the tree? Broadleaf herbicides at low levels will often cause the leaves to be distorted, but over time the effect may be to kill or severely injure the tree. Did you change the herbicide you used last year? A new or different herbicide would have different effects. Again, consulting the experts at your local Cooperative Extension Service Office would be helpful in identifying the problem.

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.

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