If the gummosis is located on the lower trunk and has sawdust mixed-in, that can indicate borer activity. If the gummosis lacks sawdust, an infection or physical injury is possible instead.

For borers, you can use the information on these pages to guide prevention and management approaches:

• Penn State -- Tree Fruit Insect Pest - Peachtree Borer
• Virginia Tech -- Home Fruit Disease and Insects management guide, listed under peaches on the page/section 3-15 and 3-16
  • Note that the active ingredient esfenvalerate is not available in a homeowner-applied product, though you might be able to hire a certified pesticide applicator to apply it for you. Otherwise, the next best thing would be a pyrethroid like the active ingredients bifenthrin or lambda-cyhalothrin, which are available in several products. Make sure anything use on a fruit tree is labeled for use on fruits.

If borers or gummosis have been a multi-year issue and the tree is in decline, consider tree removal and replacement instead, since too much damage will have been done. No treatment can cure existing disease or reverse the damage from borers; the sprays mentioned above merely interrupt the life cycle so new generations don't colonize the tree. Borers tend to target trees under stress or which have been wounded, so if the tree happens to be growing in an area surrounded by lawn, make sure it's protected from accidental mower strikes by a ring of mulch (or a wire cage around the trunk if deer rub antlers on the wood in autumn).

Miri