If you want to pamper your tree, mulch it (if it's not already mulched) or extend the mulched area out a little (if it's in a smaller mulched area). Mulch -improves soil fertility and texture as it breaks down, -prevents germination of many weed seeds, -reduces competition for food and water from grass and weeds, -reduces erosion, -helps to maintain soil moisture during dry periods, -often aids drainage by preventing surface crusting and sealing, -can keep roots cooler during hot summer weather, -can help to moderate soil temperature fluctuations, -reduces frost-heaving, -reduces certain soil-borne diseases by preventing soil and fungi from splashing onto foliage, -prevents damage from mowers and trimmers, -and improves the look of the landscape.

are all the suckers attached to the trunk, perhaps from below ground ... and all green.. if so.. they must be removed ... you will need to learn how to prune this thing... to keep it in some form which you will prefer ... just removing dead stuff.. at height.. is not going to be good.. in the long run ... you have to have a vision ... and so some proactive pruning for the future ... to keep a will in check.. you will have to learn about rejuvenation pruning ... and then about growing a shrub on a standard [in a tree form].. combine said knowledge.. and then act accordingly ... without physically being.. there.. and being able to stick me head into the plant.. and see whats there.. i have no clue how to advise you here .. see link... flip to web side for name there is a woman in the area... and hers are magnificent ... and she cuts them back to near sticks every early spring ... i swear she is going to kill them every year ... and every year.. they are sublime ... just keep in mind.. its a willow ... it is extremely aggressive ... and you probably cant kill it thru pruning if you tried ... but for those green ones at the bottom.. if they are green.. it indicates the plant was grafted to a standard .... and you have some limitations as to how far you can cut back ... at the link... find the latin name.. and add to it.. PRUNING ... and then search and learn ... read up... and ask us to clarify anything that might need such .... welcome to GW .... good luck ken Here is a link that might be useful: link

From your photo, it looks like an ash tree, but it's not close enough to tell. Other possibility is a hickory maybe? Same with the disease issue. Too hard to tell from the photo. But, if it is an ash tree, it's probably Ash Anthracnose. It's warm and very wet in Chicago this year, right? Perfect conditions for this: "Ash anthracnose is probably the most common disease of green ash. It is caused by a fungus and occurs during cool, rainy weather. It can be confused with ash plant bug and herbicide damage. Individual trees vary in their susceptibility to anthracnose to the extent that some trees may be infected every year and others only rarely or never at all. Initial symptoms on green ash include very small (grain of sand-sized) purple or brown spots, sometimes with a cream-colored center, on young leaves. These spots may enlarge and coalesce forming brown blotches. Leaves often become distorted and drop and young shoots may be killed. Defoliation and leaf browning cause homeowners a great deal of concern, but treatment is generally not warranted. Affected trees usually put out a second flush of leaves and make up for lost time later in the growing season. However, trees that have been defoliated three to five years in a row might benefit from chlorothalonil, mancozeb or thiophanate treatment at budbreak to prevent infection. The fungus can overwinter on the ground in infected leaves and twigs, so raking and disposing infected material may help reduce infection the following spring." Your main link didn't work for me -- brought up a screen, but no photos, looks like you have to create an account to view them, and I didn't want to do that. Here is a link that might be useful: Pamphlet where I got the Ash Anthracnose info:

there are all kinds of variations on the theme ... its the thin leaves that are easy to set you on the right track ... and of course.. it standing next to water ... just btw.. they are not good backyard trees .. so just kill that dream .. if thats where you are thinking of going ... ken