Answer: If you've read about Peach Leaf Curl, then you know it is caused by a fungus. A fungus is a disease so insect killer won't affect it, but it might adversely affect the leaves on your tree. I guess you found that out after you sprayed your tree. You may have to put your tree on an annual spray program to keep it from developing Peach Leaf Curl again. (Be sure to read and follow the label directions.)
The oozing sap may be signs of boring insect (Peach Tree Borer), or it could be a disease. External evidence of peach tree borer tunneling is a wet spot on the bark or the presence of oozing, gummy sap. The sap is clear or translucent and often dark from the sawdust-like excrement of the insect. Most injuries occur along the lower trunk beneath the soil line. Lower branches rarely receive injuries. Oozing wounds on peach that produce an amber-colored gum may be caused by cytospora canker, a fungus disease often confused with peach tree borer. The Cytospora fungus attacks trees or parts of trees that are injured or in a weak or stressed condition. It can cause their death. Trees affected by drought, Insects, defoliation by fungi, sunscald, herbicides, or mechanical injury are susceptible to cytospora infection.
You'll need to determine which of these problems might be affecting your tree before you can take control measure.
Best wishes with your peach tree.
Q&A Library Searching Tips