An update on our Maples: It’s been quite a spring

0

It is kind of hard to remember the month of April with its cool sometimes outright cold and rainy conditions when we are sweltering in the 90s.

April gave us a blessing in disguise. In late March and early April, the silver and red maples were in flower. Then — bam — the temperature dropped to below 24 degrees Fahrenheit, and a miraculous thing happened. The maple flowers froze disrupting pollination and there was no development of Winged Samaras. Winged Samaras are the seeds of Maples also called whirligigs and helicopters.

During that same time in April, I was receiving calls about protecting emerging perennials and daffodils. I found it amusing no one was concerned about their maple trees. I also find it amusing no one has called about missing the annual seed fall from their maples.

So, does this mean we will have double of Winged Samaras next year? Time will tell.

Another issue happening to our Maple trees is leaf drop. Some of our Maples have leaves falling. If you did not know what was causing the leaves to drop you most likely would blame it on windy conditions. We sure have had our share of windy days.

In this case an insect is causing the handiwork known as the Maple Petiole Borer (Caulocampus acericaulis). This non-native sawfly was introduced into the United States from Europe. Leaves that drop may appear perfectly healthy or the leaves wilt and turn brown while still attached to the tree. However, all the fallen leaves will retain only a small portion of a hollowed-out petiole. The petiole is the small stem like leaf tissue that attaches the leaf to tree stems.

Look closely at the fallen leaves for abnormally short petioles and examine the tree canopy for broken petioles that have remained attached to tree stems. These are telltale symptoms of a petiole leaf borer infestation as opposed to leaf loss from hail, or high winds.

The sawfly spends the winter in the pupal stage buried 2 to 3 inches in the soil beneath the affected tree. Adults emerge in the spring. After mating, the females use their saw-like ovipositors to insert a single egg into the petiole near the leaf blade. The resulting grub-like sawfly larva feeds by boring down the center of the petiole.

The larval feeding damage causes the petiole to break near the base. However, the larva remains in the portion of the petiole that remains attached to the tree. Eventually, the portion of the petiole that remains attached to the tree stem will also detach and drop to the ground where the larva crawls into the soil to pupate. Unfortunately raking and destroying fallen leaves will not reduce the sawfly population. The Good news this insect does not repeat itself throughout the summer. The leaf loss from a maple petiole borer infestation may appear significant; however, our perception may not reflect reality. It is rare for the leaf loss to rise above 5% of the total canopy. This level of leaf loss has no significant impact on the overall health of affected trees.

I guess we do not need to feel sorry for our Maples. Enjoy the shade under the sweltering summer sun.

No posts to display