Leaves are falling from 2 of my elm trees this spring. A percentage of the leaves on the lower branches are indeed brown, but the fallen leaves are green. I have upwards of 50 elm trees on my property, but these 2 seem to be the only ones with this issue.
Since you have so many elm trees I would suggest that you contact a certified arborist who can come out and take a closer look at the trees (healthy and unhealthy). The arborist should also be able to provide more details for a treatment plan if one is recommended. You can find a certified arborist in your area through the link below. I suggest you call and find out the cost and the services they offer. Hope that helps and good luck!