Answer: Extended drought conditions can really stress a tree, but one that has been in the ground for 9 years should be able to overcome the problem. About the only thing you can do is to water your tree once a week. Start by building a water well or basin beneath the tree, by mounding up a few inches of soil in a circle - about 2' from the trunk. Fill this basin with water, allow to drain, then fill it a second time. Watering in this way will concentrate the moisture directly over the root mass and allow it to trickle down and wet the entire root mass. Once a week is all it needs and you should see an improvement in your tree later in the season.
Best wishes with your river birch!
Q&A Library Searching Tips