Blueberry blossoms with worms

Credit: mac-ivan

Q: Dear professionals – I have two questions for you.

I have four blueberry plants. Last year, they started with lots of blossoms but suddenly all the blossoms, and even some leaves, were eaten by little green worms. What can I do to prevent this from happening this year?

I live in Richmond B.C. where using strong insecticides is discouraged. Also, our neighbours erected a wall to increase the elevation of the neighbouring lot. It is made of 4×6 dark brown wooden beams. On top of it, there are upright 4x4s to support the cedar fence. I know this is treated wood as there are many holes in the wood.

Would it be dangerous to grow edible plants near the wall and fence?

Thank you.

The blueberries are probably being chewed by either “ Winter Moth” or “Bruce Spanworm” (Operophtera brumata or O. bruceata), which usually spin silken threads while “Obliquebanded Leaf roller” (Choristoneura rosaceana) tend to roll up leaves.

When touched, the latter worm tends to move backwards. Monitor buds, shoots and blossoms clusters in late March for damage. Control measures need to be applied shortly after eggs have hatched, but before larvae have gotten into the blossoms. Handpicking might be one method. Spraying with a biological compound like “Btk” (Bacillus thuringiensis, kurstaki) as per label rate might be another.

As for growing edibles next to treated wood, it usually comes down to a person’s own comfort level with the idea.