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LifestyleColumnistsJessica Damiano

Help for gummosis, tiger bee flies and pear tree rust

Peach borer damage leads to gummosis in Barbara

Peach borer damage leads to gummosis in Barbara Obstgarten's weeping cherry tree. Credit: Barbara Obstgarten

DEAR JESSICA: We have a beautiful weeping cherry on our front lawn, but its leaves are dropping, brown and curled. My husband found some pinkish/reddish “gunk” on a part of the tree, scraped it off and went to a local nursery to ask what it was and what to do. The man at the nursery said it was a “bore” or “bora” and there was nothing we could do and that the tree was going to die shortly. Do you know of anything we can do to try to save this huge, beautiful tree? — Barbara Obstgarten, Port Jefferson Station

DEAR BARBARA: That’s gummosis, which results from either a borer infestation or a bacterial or fungal infection. After you confirmed via email that you are seeing sawdust-like material near the leaking sap, I was able to deduce your problem stems from borers, likely peach tree borers.

The insects bore holes into trees, leaving both sawdust and frass behind. Frass also looks like sawdust but is excrement. Borers are difficult to control, unfortunately, but pesticide applications can help, and some, like bT, spinosad and neem oil, are natural and have shown effectiveness. Still, you should try to remove as many borers as possible first.

If any branches are dead or have holes in them, prune them away. Clear away any fallen leaves or debris from the base of the tree, and keep mulch 4 inches away from the trunk.

Gently stick a pocket knife or other thin, sharp object into the holes in the trunk and pry out and kill any borers that are in there. Another hiding spot for cocoons is at the base of the trunk, so dig up a bit of the soil around the tree and remove and discard (in the trash) whatever may be lurking there. Be very careful not to further injure the tree when you’re doing this, obviously.

Next, apply a trunk spray formulated against peach tree borers in mid-May and again between July 20 and Aug. 1, soaking the trunk from the soil line up to the canopy (but not the leaves). Be sure to follow label directions precisely.

As an added measure, paint the bottom 2 feet of the tree with white latex paint in early spring to discourage borers from laying eggs.

DEAR JESSICA: I spotted these unusual insects in my flower garden. Do you know what they are? Are they harmful? — Laura Casini, Malverne

DEAR LAURA: That’s a tiger bee fly. It’s not actually a bee, however; it’s a bee predator that kills carpenter bees when they’re in a larval stage. Although carpenter bees are beneficial pollinators, they also can damage your house. I’d leave them be and let nature sort it out.

DEAR JESSICA: My pear tree has rust disease, and I can’t make up my mind about whether I should take the tree down or rake up diseased leaves all summer. But my main concern is whether the fungus is harmful to us humans. — Jim Martin, Wantagh

DEAR JIM: Pear tree rust is not at all harmful to humans. As you pointed out, it’s a fungal disease, and frankly, it’s not even that harmful to trees.

The fungus manifests as bright orange spots on foliage, which looks like rust. Sometimes swelling, or cankers, will be present on branches as well. The pathogen also affects junipers, and both plants must be present for the fungus to complete its life cycle.

If you don’t have junipers growing on your property, someone nearby does, and a close look at them would likely reveal galls on branches and gelatinous, orange, hornlike growths during spring. Those growths contain spores, which are carried by wind to infect your pear tree.

To stop the cycle, affected juniper branches and your pear’s leaves and branch galls must be removed. This isn’t practical, however, if most or all the leaves are showing symptoms. Spraying trees with a fungicide labeled for use against Gymnosporangium may offer some protection. And if the junipers are yours, removing them altogether would provide even better protection for your pear tree.

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