Thank you for waiting. Normally, I would have turned your question over to another expert, but I was the only one available in this category today. After reading up on ash problems in New Mexico, I think it's most likely your tree is suffering from environmental stress. Your strange winter weather is one factor. That alone can cause leaves to be slow to develop in the spring. However, your area has also been under drought conditions for some time. I understand that is lessening now, but the damage has already been done to trees. Symptoms of drought stress/damage in the ash tree include yellowing leaves (the lighter color) and slow development. The green ash is not native to your area, and its native range is in areas with much more moisture than what New Mexico gets even in a wet year.
A tree that is stressed by environmental conditions often becomes a target for fungal infections and insect pests. There is a disease called ash yellows, which has been found in the southwest. It attacks trees under stress. Ash trees often end up having multiple problems, and then something referred to as ash decline develops.Leaves are small and undeveloped, pale in color, twigs begin to die, and with ash yellows, defects referred to as witches' brooms occur on branches and the trunk. Here is what they may look like:
Given all the circumstances, it may be difficult to save the tree. It is essential to provide it with plenty of water. I would also fertilize it with a good all purpose tree fertilizer, available at nurseries and garden centers. If you see signs of insect pests, such as holes bored in the trunk or branches, it would be best to consult an arborist for treatment.
If you end up losing the tree, you may want to consider replacing it with a drought-tolerant tree native to the Southwest. Here is a list of some:
Colorado Blue Spruce
Douglas Fir or Oregon Pine
Net leaf Hackberry
New Mexico Olive
Rio Grande Cottonwood
If you have more questions, let me know in a REPLY. I hope that whatever you decide to do, it will work out well. Thank you again for your patience.
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