Sticky Substance on Tulip Trees
We've had a number calls regarding a "sticky" substance under tulip trees. I have grown up with this situation-- I have a century old tree in my yard and have had this in various degrees throughout the years. The cause of the "sticky rain" is scale insects on the branches and young "crawlers" on leaves and branches. They are nearly microscopic with the most visible sign of the "scale" being the bumps or blister-like houses they create. This year the situation has been made worse due to a very mild winter and an earlier than normal spring with less spring rain.
The fun fact is that the sticky substance "honeydew" which they excrete... (poo) is a delicacy to ants and wasps. Then as it rains down, and you can literally see it. It piles up on plants and items below as it transforms into a "sooty" black mold which can be washed of hard surfaces, and if done gently, even from hosta and other plants.
Treatment: There are several products and methods and some are not practical for the home gardener due to the height of the tree. "Tree & Shrub Systemic Insect Drench" – Imidaclorid, is perhaps the easiest treatment for larger trees. Use 1 oz. per inch of distance around trunk (measured at chest height) this number will be the number of ounces to apply. Treatment is best done after the flowers have dropped to prevent injuring bee that pollinate them.
As I mentioned before, having experienced this since a child growing up with this majestic native state tree in our yard, this is perhaps the worst year I remember. Normally this would occur in June and not always to this degree, the scale are always here and are a native insect. As always, at Whiscmeier Nursery are here with solid information and knowledgeable staff to assist you.
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