If the tips of your blueberry stems suddenly start wilting, it’s probably blueberry tip borers. Blueberry tip borers (Hendecaneura shawiana) are the larvae of moths. These are not the same thing as blueberry stem borers (Oberea myops), which are a type of beetle.
Blueberry tip borer description
I couldn’t find photos that I could use, but these mottled brown moths look like they have a white saddle and their antennae tend to be long and thin. If you get your hands on one, you may be able to see that they have orange marks near the tips of their wings and a one-half-inch wingspan. The larvae are somewhat yellowish and the eggs are translucent.
Blueberry tip borer lifecycle
Eggs are laid on the underside of leaves. Once they hatch, larvae burrow into canes, usually within half an inch from the tip of the shoot. These larvae feed all summer while inside the plant and then overwinter in their protected space, before pupating in spring.
Managing blueberry tip borers
If new shoots suddenly start wilting, take a closer look. You may be able to see tiny pinhole entries. Tunneling and feeding by blueberry tip borers result in stem wilting and leaf browning, especially around leaf edges.
If you suspect blueberry tip borers, remove an affected shoot and cut it open lengthwise. If you see borer larvae, it’s a good idea to prune out any infested shoots. If you can catch the larvae between hatching and boring, you can apply Bacillus thuringiensis (Bt). Once inside a plant, these pests are pretty safe from whatever you might want to spray.
Like most other blueberry pests and diseases, this one is still mostly found on the East Coast. As more people around the world start growing blueberry varieties that need fewer chill hours, those problems will also spread, so be forewarned.
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