Q. What's wrong with the Dawn Redwood trees on my street?
A likely source of your dawn redwoods' troubles is salt damage. When road salt is compounded with fertilizer salt, sodium ions accumulate in twig tips and leaves, causing browning and burn.
Dawn redwood is a robust species, so cut down on salt by skipping the fertilizer entirely for the next 3-4 years. Use only mulch. Water deeply and cultivate gypsum into the top 2-3 inches of the soil every spring to lock up salt. Try to protect the trees from sidewalk deicing salt and splash from the street. Prune out the dead wood.
If salt damage is indeed the problem, the tree tip--its topmost point--is likely to die. If that happens, selecting and training a new "leader" will be necessary. This procedure involves splinting an upper lateral branch into a vertical position, so that it develops into a new apex. A certified arborist can perform this repair.
For tips on a variety of gardening topics, see our Plant Information Guides.
- Courtesy of NYBG Plant Information Service