Q.corkscrew willow
My cork willow is planted in a large pot (15 gal.) It is about 10 ft. tall and
about 3 years old ,but in the last two weeks the leaves have turned yellow and
about 75 percent have fallen off.
Do you have any suggestions that I can do to save it?
You may not be able to keep this plant in a container for a long period of time.
Corkscrew Willow is fast growing and will outgrow a container quickly.
Keeping it pruned both above the pot and it's roots will help keep it contained.
Soil should be changed each spring to keep it healthy. A good quality commercial potting mix is fine.
Corkscrew Willow is a heavy feeder and you can help keep it compact by feeding it a 3-1-2 or 2-1-2 fertilizer ratio.
Make sure the container has plenty of drainage holes so you can keep an eye on the roots. When they start poking out, it's time to repot.
Watering is crucial, soil should be moist but never soggy. If roots dry out, the plant can die.
https://www.gardeningknowhow.com/ornamental/trees/willow/growing-a-curly-willow-tree.htm