Question
Saw your answer to a previous post that a "fertilizing" turfbuilder could be to blame for the yellowing of weeping willow leaves...  We may have the same problem.  What can be done to stop the yellowing?  Will the leaves return or will the tree die?

Answer
If you used a fertilizer on the grass under and around the tree that contains a weed killer then the yellowing maybe from this. IF so about all that can be done is water and try to dilute the concentration of the herbicide. Try watering every other day for a week with 1 inch of water (place a pan under the tree and turn the water on and when the pan has 1 inch of water in it stop). After a week water once a week if it does not rain. Hardwoods will leaf out again if they loose their leaves.

If it still has not started to put on leaves check and see if the tree is dead. Start near the end of a upper outer branch and scrape a small bit of bark off the branch, if the color under the bark is green then the branch is still alive at this point on the branch. If the color is brown then the branch is dead at this point on the branch. If brown continue down the branch scraping at intervals until you find green or reach the trunk. If brown try other branches until you find green. OR you can just wait and see if the tree will leaf out again.