Rows of peach frass

On several of my older peach trees I hve been seeing rows of frass on the branches. These are older branches, 3 to 6 feet off the ground. The sites oozing frass are small, 2 to 4 inches apart, and in a row of about 5 to 15 sites. Nearby branches will be fine. The foliage and fruit on the affected branch seem fine for now. The location and pattern doesn’t conform with what I would expect from Lesser Peach Tree Borers, which I have in the trunks and crotches of trees lower down, or with what I have seen from Peach Twig Borers, which start in new growth at the ends of branches.

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Turkey Creek Orchard
Solon, Iowa (zone 5A)



Edited 1 time(s). Last edit at 07/11/2021 08:43PM by Peter Fisher.

Excavate one of those, Peter, and report back. This looks more like a gummosis response than frass from an insect larvae. That said, the randomness of branches afflicted sounds more like an insect doing the deed. It helps that you already have Lesser Peach Tree Borer ruled out. If you do find a grub of some sort, one suggestion would be to use your pocketknife and continue excavating. Or trial applying pure neem on the branch surface (like we do at the base of apple trees for roundheaded appletree borer) noting I do not know how peach bark up high will react to this. Play around with nicking off the gummosis mound to helps make the entry point more accessible. If it turns out to be fungal in origin, biodynamic tree paste would be the way to go. I'd do the same for bacterial canker too. I've had good results merely rubbing soil into black knot lesions of a plum wherever I see such developing. But of course we need to know if this is caused by an organism or an insect.

Expecting the unexpected is going to become a normal part of orcharding in a stressed climate.

Lost Nation Orchard
Zone 4b in New Hampshire



Edited 1 time(s). Last edit at 07/11/2021 03:00PM by Michael Phillips.

I have seen similar neat rows of holes in other contexts, caused by birds such as sapsuckers, (who make the holes for precisely this purpose), and flickers, (who walk upside down, down trees, pecking for grubs.). But both of these make their rows of holes much closer together. And I have never seen either of these go after peach trees.

Broomholm Orchard
Zone 5b in Nova Scotia

I should have described it as gummosis not frass. Scraping it off just reveals the bark beneath, with only the tiniest hole or crack identifiable as the source of the oozing gum. I had thought I might find burrow holes indicating a peach bark beetle or a shothole borer but could not find any such thing after excavating several spots. (Those two possibilities were the best I could some up with from the Tree Fruit Field Guide.) Bird poop on a few branches, but that hardly qualifies as evidence of birds pecking holes. Also, there were branches where the gum was on the underside of the branch.

Today I discovered two instances where the smaller branches off the somewhat larger branch with the gummosis are dead or dying. These are 12 year old trees, past the average life expectancy of a peach tree I think. Lots of cracking and peeling bark on the older branches.

I am tempted to remove and burn the branches with severe gummosis.

Turkey Creek Orchard
Solon, Iowa (zone 5A)