My peach tree has some yellowing of small leaves in the center of tree. I do believe it has enough water. Is this something to worry about? I see small black ants on the tree as well as a small black fly of sorts flying around the tree. Should I be using an insecticide on this?
The leaf yellowing is due to stress. Since you mention the ants and flying insects around the tree, my guess would be that is has a pest of some kind, likely aphids or a similar sap-sucking insect. They generally tend to secrete honeydew, a sticky substance which may be present on the leaves. This honeydew is what attracts the ants and flies. I would recommend treating the tree iwth neem oil, which should take care of the pest problem and in turn take care of the ants and flies. It is also safe to use and an effective fungicide as well should other issues pop up due to the stress from the pests. It is often sold as fruit tree spray at stores. Check the label. Here is more information: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm