Garden Detective

Sun may be setting on this Red Sunset maple

A red maple leaf on the campus of Sacramento State hangs on to its tree during late fall. These trees are susceptible to fungal diseases.
A red maple leaf on the campus of Sacramento State hangs on to its tree during late fall. These trees are susceptible to fungal diseases.

Experts tackle readers’ garden questions.

Q: I have a 15-year-old Red Sunset maple that has been beautiful during the growing season and vibrant when the leaves turned red in early November. It’s approximately 30 feet tall. The last two years, the tree develops what I will call premature leaf coloring in sections of the tree. The leaves come out fine in March and April but, by June, certain sections of the tree are showing color changes in the leaves. By September, the leaves are falling in these sections. I have been told by a arborist that this condition is a fungus for which there is no cure and eventually the entire tree will die. They said it has something to do with sprinklers getting water at the crown of the tree. Do you agree with the diagnosis?

Steve Mawhinney, Roseville


Master gardener Annie Kempees: There are several diseases that can affect the health of your tree. Phytophthora root rot and Verticillium wilt are two. Planting habit, soil type and watering practices all affect how your tree lives or dies.

Verticillium wilt is a soil-dwelling fungus that infects the tree through the roots. It affects plants’ vascular system. By interfering mainly with the xylem tissue, these vascular wilt diseases cause foliage to turn faded green, yellow or brown and wilt in scattered portions of the canopy or on scattered branches. They often begin on one side of the tree, later killing the entire plant. It may go in a single season or die slowly.

Many of the red maple’s staple problems stem from its ability to grow quickly in loose or moist soil. Phytophthora root rot, a fungus, particularly causes problems for maples in poorly drained soil. The disease usually affects trees or plants grown in a container or those cultivated in fields.

Phytophthora root rot chokes the tree, reducing its ability to bring water and nutrients into its system. Symptoms of phytophthora root rot include yellowing of the leaves, early leaf shedding, slow growth, dying branches, and reddish-brown discoloration beneath the bark at the soil line. On some trees, water-soaked cankers ooze liquid around the soil line.

Unfortunately, phytophthora root rot results in an unstable tree, which also makes it prone to falling over during a storm or particularly wet season. For the safety of humans and property, a red maple’s fight with phytophthora root rot often ends with a visit from a tree cutting service.

To assist with identification of your issue, bring a sample to the Placer or Sacramento County Cooperative Extension Office. The sample should include both plant parts exhibiting symptoms and healthy portions. Keep the sample moist until delivery.

The Sacramento office is located at 4145 Branch Center Road, Sacramento; 916-875-6913. The Placer office is located at 11477 E Ave., Auburn; 530-889-7385.

Annie Kempees is a UC Cooperative Extension master gardener in Sacramento County.

Garden questions?

Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties. Send questions to Garden Detective, P.O. Box 15779, Sacramento, CA 95852. Send email to h& Please put “Garden Detective” in the subject field and include your postal address. To contact UC Extension directly, call:

  • Sacramento: 916-875-6913; 9 a.m.-noon and 1-4 p.m. Monday-Thursday
  • Amador: 209-223-6838; 10 a.m.-noon Monday-Thursday; email ceamador.
  • Butte: 530-538-7201; 8 a.m.-noon and 1-5 p.m. weekdays
  • Colusa: 530-458-0570; 9 a.m.-noon and 1-4 p.m. Tuesdays; website:
  • El Dorado: 530-621-5512; 9 a.m.-noon Tuesday-Friday
  • Placer: 530-889-7388; 9 a.m.-noon Tuesday-Thursday or leave a message and calls will be returned; website:
  • Nevada: 530-273-0919; 9 a.m.-noon Tuesday-Thursday or leave a message
  • Shasta, Tehama, Trinity: 530-225-4605
  • Solano: 707-784-1322; leave a message and calls will be returned
  • Sutter, Yuba: 530-822-7515; 9 a.m.-noon Monday-Tuesday and 1-4 p.m. Thursdays
  • Yolo: 530-666-8737; 9-11 a.m. Tuesdays and Fridays, or leave a message and calls will be returned