Nectarine Tree - ooze

Asked May 25, 2015, 10:54 AM EDT

Hello! I have two nectarine trees. One is a Hardired dwarf, the other a Startk SunGlo Dwarf. Both planted in 2009. One of the trees is covered (all the branches) with drop of a sticky, clear ooze. At the bottom of the trunk is something that looks like Greater Peachtree (Crown) Borer. Using the link belowe, I applied one round of SEVEN (powder) around the trunk. The tree bore fruit two years ago, but it all appeared to have a fungus, so no crop. Please help.

Wayne County Michigan

1 Response

I agree with your diagnosis of peach tree borer, based on the sawdust-like material on the lower trunk. The Sevin helps to prevent new infestations, but does not kill larvae that are already present. You can dig/poke with a knife around the area with the sawdust (use gloves because you treated with sevin) to find and remove any borer larvae. You may need to move a few inches of dirt away from around the crown temporarily to be able to gain access. Look for more gum, grooves. See attached picture to see what you would be looking for. They range from 1/4 to 2/3 inch long, have darker head capsules, and are white / slight pinkish.

When I see extreme gumming on peach and nectarine as shown on the first picture, I generally suspect san jose scale, or less commonly peach white scale. See attached photo that shows the abundant tiny dark scales, much like dandruff. With scale the wood under the bark show red discoloration.

I don't have pictures of peach white scale, but you can search the internet and see articles on this. With a better closeup picture of your bark I may be able to check for these two.

Another possibility is botryosphaeria gummosis, which is a fungal
disease we see occasionally in Michigan. There is no cure for this.

We also have been seeing quite a bit of gumming on peach simply due to winter damage. But we generally don't see that much gumming. This can roughen the bark up.

My first guess is that you have scale, based on the extreme amount of gumming. Dormant oil spray is the most effective strategy for this---there are sprays that can be timed to hit the crawler stage. But you need to confirm the diagnosis.

Roundup drift can cause gumming on peach. It too will roughen bark up.

Armed with these descriptions you may be able to pin down a culprit.