It’s a heavy seed year for silver maples (Acer saccharinum) this year. Many of our landscape specimens are teaming with keys which are starting to helicopter to the ground. Silver maples are wind pollinated and one of our first trees to bloom in early spring. Since we didn’t have frosty nights for most of their early development, they’ve got a bumper crop this year. Silver maples seem to fruit heavy every 5 years or so, its nothing unusual. But in some cases, there’s more seed than leaves!
We’ve seen this before and usually the trees will flush out again after seed drop. It’s been so dry, some slow irrigation around the root zone will help the trees recover a little faster. Or some rain, RAIN would be nice.
Have you ever noticed holes in red oak leaves, searched high and low for leaf chewing insects and come up with nothing? Even when you come back a different times of the day? You might be interested to know that researchers figured this out back in the 80’s. There is a teeny-tiny-weenie-beenie fly called the Oak Shothole Leafminer (Agromyza viridula). The adult female injures leaves in order to lap up their juices. Here’s a description from Ohio State University:
“In early spring, the adult female flies puncture expanding oak leaves with their ovipositors in order to make the leaf liquids available for food. These puncture wounds expand as the leaf reaches full size. The tiny holes can become 1/8 to 1/2-inch in diameter and numerous holes may be present in an affected leaf. The most diagnostic feature of these shot holes is that some will have a tiny knob sticking out along the hole rim. This tiny knob may also have a tiny pin hole visible. The damage is most evident on red oaks though white oaks are also attacked. Occasionally females will lay eggs in oak leaves and their larvae make blotch mines.”
So it’s not another invasion, it’s a creative-thinking little Agromyzid!