Hello Rose,

I am sorry about these trees which appear to have different problems, but the causes may have something in common. Quite frankly, they don’t look healthy, and you will have to decide if they are worth trying to save.

Without knowing your watering schedule, these trees appear to be quite stressed which may be caused by a lack of water or other environmental issues. While these trees have been here for two years, based on the width of the trunk they are still getting established. The general rule is one year for every inch of trunk caliber and during that time frame frequent light watering is required. I am attaching a link which provides further detail for water requirements.

https://cmg.extension.colostate.edu/Gardennotes/635.pdf

Witches Broom: This response from another Master Gardener appears to address this problem, so I am including it and the link they provided

Hackberry Witches' Broom is a disease caused by a complex involving a powdery mildew (Podoshaera phytoptophila) and an eriophyid mite (Eriophyes Celtis). This condition is very common in Colorado. The brooms are more unsightly than harmful to the tree, but the brooms can cause branches to break more easily. A large number of brooms can reduce tree health and stunt the growth of the tree.
To manage the problem, prune diseased twigs and maintain good tree care practices to reduce any stress and maintain tree vigor.
https://hortnews.extension.iastate.edu/1995/6-23-1995/hack.html

Leaf Gall: While nipple galls are a common problem in hackberry trees, I can’t tell from the photo whether it is a fungal infection or nipple gall, so I have attached information which I hope will help.
http://cues.cfans.umn.edu/old/Web/144HackberryNipple.p
https://extension.colostate.edu/topic-areas/insects/insect-and-mite-galls-5-577/
Dead leader: It appears that you have already tried to prune this tree, which is the best solution for a dead leader. Unfortunately, you will have to decide whether this tree is worth continuing to try and save. I am attaching a reference for pruning young shade trees, which may be helpful.

https://cmg.extension.colostate.edu/Gardennotes/613.pdf

I hope this helps, but if you have additional questions, please let us know.