Garden Q & A: Why is my maple tree is dropping its green leaves?

Why is my maple tree losing lots of leaves now?

You said the leaves were still green when they fall, but the stems looked darkened.

There could be several reasons for leaf drop, but the most likely cause may be the leaf stalk borer or petiole borer. Both insects burrow into the leaf petiole in the spring, causing the leaves to fall. The larvae remain in the leaf when it falls and burrows into the ground and remains dormant until the following year.

These insects rarely cause significant damage. However, if infestations are particularly heavy, treating the soil under the tree with a granular insecticide during the fall may decrease damage the following year.

The University of Florida has a publication, ST-41, that you may want to look at concerning the leaf drop problem. Go to: www.ufl.edu and type in ST-41 to get to the red maple fact sheet.

Another culprit this time of year is squirrels. If the leaf drop includes small branches, I would suspect squirrels harvesting leaves for nesting materials. They also clip off the ends of branches to eat the seeds but it is a little late for that.

What would cause a horizontal line of holes about the diameter of a lead pencil throughout the trunk of my 10-year-old maple tree?

It is most likely the yellow-bellied sapsucker (Sphyrapicus varius).

This bird can cause damage to many species of trees including oak, sweetgum, maple and elm, by drilling 1/4-inch holes through tree trunks and limbs in vertical and horizontal rows.

These holes are often arranged so perfectly that you might think the bird used a ruler.

Often confused with wood borer damage, the holes fill with sap, and the bird uses its brush-like tongue to draw out the sap.

Researchers do not know how these birds get tree sap to flow so copiously. Sap is vitally important to trees, and they have developed defense mechanisms to stop sap flow when wounded. It is thought that the sapsucker's saliva may contain an anticoagulant substance.

These birds are migratory, so we have them swing by in the spring and again in the fall. They tend to come back to trees they like.

Will this damage kill your tree? Repeated attacks can girdle and kill branches or even the entire tree. The biggest concern is that wood decay or bacteria may enter through the feeding wounds.

To discourage sapsucker feeding damage on a yard tree, wrap aluminum flashing or burlap around the tapped area. Often treatment of these tapped areas forces the bird to go somewhere else.

Legally, this bird species is federally protected, so avoid using gooey repellents such as Tanglefoot, because they may injure the bird.

There are possible insect culprits, however. If the holes go deeply into the wood, they have probably been made by insects. An insect infestation would not bode well for the tree's health.

Tom Bruton is a master gardener with the Duval County Extension Service and the University of Florida/IFAS.