Arizona Ash

1. Q. The leaves are falling off of my Arizona Ash tree! What can I do to prevent this?

A: Don't plant an Arizona Ash tree is the best remedy. You have never seen that species of tree listed as a recommended variety for this area and there are some real good reasons--one of which you are describing. There is a spring-occurring fungus called anthracnose which causes ash trees in this area to experience the fall phenomenon of dropping leaves in the spring. If you are rich, you can purchase a benomyl-containing fungicide to spray with every 10-14 days. Don't worry! Unfortunately, this will not kill the Ash and it will soon releaf.

2. Q. I know there are better trees than Arizona Ash but I have several big ones growing in my yard providing wonderful shade in the summer. I am worried that one of them has suddenly died. The tree produced leaves early but all at once the leaves have dried up. Is this tree dead? Some of my neighbor's Arizona Ash trees haven't even produced leaves yet!

A: The problems you are noticing with your trees are some of the reasons the Arizona Ash is not a highly recommended tree for planting. The rainy, warm spring weather has stimulated the proliferation of a fungus disease which damages small, emerging leaves resulting in the my-tree-died complaint. Effected trees are not dead but just resting up before making a second attempt at spring leaving. It is not practical to spray fungicide on such large trees every spring to prevent this disease which may or may not occur. This is the same pestilence which can defoliate Arizona Ash trees several times during the summer. Concerning the trees which have not produced leaves this spring, don't give up on them. They are not dead, just waiting. Most Arizona Ash trees planted in this area are seedling trees which mean they are all different. Some will leaf out early in the spring; some will defoliate early in the fall.

3: Q: We have 2 arizona ash trees in our backyard. I was reading that a big problem with these trees is borers. The book mentioned a borer preventive and using this certain times of the year. What is a borer preventive, will it help and when should I use this?

A: Arizona Ash along with many of the fast-growing softwooded trees such as sycamore, mimosa, tallow and cottonwood are susceptible to borer damage as the trees get older. The only borer preventative spray which is effective is dursban spray applied to the main trunk and major scaffolds where they join the trunk for as high as possible beginning in early August and applying every two weeks for four consective sprays. Tree health needs to be maintained at a high level by not allowing the tree to drought stress and fertilize spring and fall (October). Sometimes even this program doesn't prevent the problem so recommended trees need to be planted to avoid this situation.

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