I was just wondering if I remove the suckers from the base of my Claret ash trees, and could I paint over the stub left to stop any further growth?
That would like not stop the suckers. Typically when trees are putting out suckers, it is because they are stressed. I would check to see if the tree is getting enough water, enough fertilizer and is not over watered. Checking for pests is also helpful. All of these things can stress a tree and cause them to start suckering.
I have a 20 year old Ash tree that was pruned back about 5 years ago and since it does not sprout very many leaves. The top of the tree looks to have a lot of dried branches that I want to prune off. It looks like it is barely alive but I'm hoping that with the right pruning and watering it will come back. What do you think?
Unfortunately, ash trees in the country are facing an epidemic. There is a bug called the emerald ash borer that is attacking and killing ash trees across the country. You are describing classic signs of this pest.
I would recommend having the tree looked at by a tree specialist to determine if this is the problem and be prepared to need to have the tree removed and destroyed to help keep this serious problem from spreading. Here is more information:
https://www.gardeningknowhow.com/ornamental/trees/ash/emerald-ash-borer.htm
I had my very large 50-year-old Arizona Ash tree topped last summer before the heat spell hit (100-degree temperatures for over a month). This spring there are no leaves or buds on the few twigs that grew back. Can my tree be saved?
This article will help you determine if it is still alive:
https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm
Is it possible to start a new tree from a sucker? I have a Mountain Ash that has suckers around the bottom and I would like to start a new tree. If I try to root it, will it be a tree or just a branch?
Yes, you can grow a new tree from suckers as long as you have a good section of root.
Is there something I can put around the base of my ash tree to rid it of tent worms?
I would recommend Bt on the tree. Since the parent moth flies into the tree to lay eggs, treating the base will not help. This article has more information:
https://www.gardeningknowhow.com/problems/pests/tent-worms-tent-caterpillar-home-remedy.htm
Can a healthy tree be started from suckers from the parent tree? I have a Mt. Ash tree and would like to start another one and have a couple grouping of sucker starts. . . don't know what else to call them. Can they be pruned to just one trunk and then dug up and replanted? Would you get a good tree from that? I have some starts from a Japanese Maple tree also. Can I do anything with them?
Yes, you can grow a new tree from suckers as long as you have a good section of root. You're right in thinking that only one shoot should be saved. The smaller the shoot, the more success you'll have.
A Raywood Ash tree I planted last fall has died, but I have healthy growth growing from the graft. It is different from the Raywood, so I suspect it is a Green ash. If I continue to let it grow as is, would it make a healthy, nice looking tree?
Yes, given the appropriate growing conditions, it should be fine.