Sad Trees

 Late last summer into last fall, we started to realize there was something seriously wrong with some of our trees. The leaves of some of our newer trees, volunteer tulip poplars we planted at the curb and a purchased maple, were all turning black. At first, we thought it was damage related to having a banner cicada year, since we knew that cicadas can temporarily stress trees. Many were also sticky and attracting a lot of insects, and we knew that cicadas poop honeydew (yup, that's an actual thing) So we ignored the problem, thinking it would resolve on its own.

Tulip Poplar Leaf

Maple Leaf

But it got so sticky and gross looking that we did eventually decide to consult a tree expert. And it's good we did, since it turned out cicadas were not to blame. The real culprit was a pest called scale. Leucanium scale, to be specific, which feeds on the sap from shade trees, and tuliptree scale, which feeds on--yup, tulip poplars. We had not one variety of scale, but TWO. Once an expert pointed them out to us, we couldn't NOT see them. They are the bumpy knobby things on the bark, which we had just thought WAS bark. Nope--they are gross little pests that suck at the bark. And they also poop honeydew.

They aren't very firmly attached--they can be scraped off with a finger nail (ew!). We were advised that one way to remove the scales was to pick them off and dump them in a bucket of soapy water. But of course they were ALL over the trees, out of reach in many instances. So that wasn't a realistic option. The other option, according to the tree experts, was to apply a "horticultural oil" to the tree at the "dormant rate" once the trees had dropped their leaves. This meant we should apply more of the liquid, since the tree was dormant for winter. 

As the bottle says, it "kills insects by smothering." More ew. But the point is that it is thick and oily and basically stops airflow to whatever it touches (thus why you would not want to apply a heavy coat to the tree when it was still relying on its leaves for photosynthesis).

This post is a long time coming because I wanted to wait and be able to say whether it worked. Over the winter, it was hard to guess. One problem with killing through smothering is that the scale remained on the tree, but were desiccated and dead. Much easier to scrape off and, hopefully no longer a threat. There it is on my fingernail.

As spring buds emerged, there were clearly fewer scale on the tree--many probably fell off on their own or washed off with rain/snow. I could still see some, but they were obviously flattened and dead.

Now as we enter into late spring, I think it's safe to say that we stopped the scale damage--from last year, at least. It doesn't seem like scale can be prevented, just treated. So we'll have to hope they don't come back but at least we can be ready if they do. But at least the trees seem healthy and happy (judging by all the new growth) so far! 

Happy Maple Leaves

Happy Poplar Leaves