Ash Tree Dying....Again

Q.   I have an ash tree that is 18 years old. This year about 20 percent of the tree has dead branches while the rest looks good. We really do not want this shade tree to die.

I have posted before on possible Ash Decline

https://xtremehorticulture.blogspot.com/2018/01/dieback-of-mature-fan-tex-ash.html

https://xtremehorticulture.blogspot.com/2017/10/limbs-dying-in-20-year-old-arizona-ash.html

https://xtremehorticulture.blogspot.com/2015/06/ash-dieback-or-ash-decline-they-both.html

A. That tree occupies a very important part of the landscape, I am sure. However, your ash tree may have an incurable disease called Ash Decline. In California they call it “Ash Dieback”. This disease, so far, is found only on ash trees, causes branches to slowly die in the canopy over several years. So lucky you! You can see this disease in many ash trees in the Las Vegas Valley.  But these dieback symptoms are similar to drought.

Because this ash is growing in a lawn and probably getting enough water then this dieback is suspicious. This might be ash decline. Deep water it once a week for three or four weeks and find out.

Deep Water and See if it Grows Better

            Before giving up on it, try applying more water to the base of it in a larger area. Along with its normal water application, do this once a week with a hose and sprinkler and see if that helps reduce the problem. I use a mechanical water timer that costs about $12. I adjust the water delivery from the sprinkler to about the same size as the tree canopy and water for one hour. The water should wet the soil 18 – 24 inches deep when you water. Do this weekly for one to two months. If the tree starts growing more than you must apply more water to the tree. 

Most ash trees are "mesic" and not "xeric" which means they should be given enough water when planted in a desert landscape. As any plant will, they will take water where they can get it. Are there enough drip emitters providing water to this tree? Even if you count the plants watered nearby? Maybe when its small but not when it gets bigger.

If the tree does not respond with new growth, it probably has ash decline. Remove the tree. Applying a fertilizer once a year just before new growth is enough for trees. This would be February in the Mojave Desert.

Note: I am no longer answering ash branch dieback questions here. I posted a page to it in my blog. I will respond to queries to me in an email but not post an answer.