leaves dropped from weeping willow tree

Asked June 8, 2015, 3:21 PM EDT

Hello, I have a willow tree that was planted three or more years ago. This spring the tree budded and leafed (if I can use that term) as usual. Last week during the storms we had the leaves started dropping. By today most of the tree is bare. The branches are mostly green and supple, the trunk looks fine, the root flare looks good, the leaves that fell were not spotted, and I don't see any bugs. We had a dry spell here for a few weeks but I didn't water the tree this year because I thought after three years it was established enough to be ok for a few weeks without water. Last week we had some heavy rains and it has rained at least a small amount every day since then. Do you think a short dry spell could affect a 3 year old weeping willow? Should I water the tree even though we have had rain? Can you think of another reason for the leaves to drop? Can you think of anything else to do? What do you think the prognosis is for this tree? Thanks very much, Mary Clarke

Delaware County Pennsylvania

3 Responses

We are having a gypsy moth infestation this year, and the willow is a favorite food of the caterpillar. They typically strip a tree and move on to the next. If you have gypsy moths on your property, there's a good bet they did the damage. Often they leave bits of shredded leaf debris and black tiny dot sized balls they excrete as they feed.

Thanks for getting back to me. Sorry, I didn't mention that the leaves had no holes in them and seemed to be all on the ground. Not sure if you still think gypsy moths.
If the problem was caused by gypsy moths, what should I expect from the tree? Should I be watering a three year old tree now that it's hot and not raining?

Thanks very much.

If there were gypsy moths, you would see signs of them. The caterpillars are big by now and are crawling on the ground as well as in the trees.
From my research it appears that weeping willows will drop their leaves if they are stressed. Their preferred habitat is the bank of a creek or river. They like their head in the sun and their feet wet. Since there is no obvious pest or pathogen, the dry spell followed by heavy rain could have caused leaf drop. Some willow owners report leaf drop as a regular event in their location. Here is a link to a fact sheet published by the Missouri Botanical Garden on Weeping Willow and a link to a forum on willows run by NDSU Extension. I would say that it is important to monitor the soil and not let it dry out.