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It is time to check your trees for Sudden Oak Death from now until the end of December. Phytophthora ramorum is the mold pathogen that causes Sudden Oak Death. It is most active when it is wet, and it is most likely to spread when it is raining and muddy.
Since it was first found in 1994, Sudden Oak Death has killed more than a million trees along the coast of California. There is the disease in 14 counties, and Santa Clara and San Mateo are two of them.
In the Peninsula region, it was first found in 2000 in Long Ridge Open Space Preserve in La Honda. The Midpeninsula Regional Open Space District says it is now a major threat to trees in the Santa Cruz foothills.
Sudden Oak Death is a forest disease that mostly affects oaks, like the California coast live oak, black oak, Shreve’s oak, canyon live oak, and tanoak trees. However, it can also spread to planted yards near wooded areas and further away.
The mold that looks like a fungus can be found in soil, water, and infected plants. When infected plants or dirt are moved, the mold can spread to new areas.
The pathogen has been found on more than 100 different types of plants. These include shrubs, herbaceous plants, ferns, hardwood and evergreen trees, and more.
The California Oak Mortality task force says that they only cause leaf spots and shoot dieback on most plant types and do not kill them.
Sudden Oak Death is a very real danger to oak and tanoak trees, but you can protect them if you take care of them.
Here are some ways to spot the sickness, treat it, and stop it from spreading:
Look for symptoms
Sudden Oak It can be hard to tell someone has died until a lot of damage has been done. The signs and symptoms are a lot like those caused by other fungi, bugs, or external factors.
The infection can turn leaves brown quickly without a long time of decline that can be seen, which is how the disease got its name, “Sudden Oak Death.”
To control Sudden Oak Death, it is important to find it early. Walk around your land and look for signs of trouble in your oak trees. Weak leaves, rapid leaf loss, oozing cankers or mushrooms growing at the tree’s base, and dying twigs are all signs that something is wrong.
Get a laboratory diagnosis
In the event that you notice any signs, it is important to get a professional analysis. You can only be sure that a plant has phytophthora ramorum by sending a piece of tissue to a lab to be checked.
If you think your plant might be affected, look at the USDA’s list of plants that can get Sudden Oak Death to see if your type of plant is on it. Since this disease is still pretty new, the list of hosts keeps growing as more study is done.
Check the California Oak Mortality Task Force Symptom Gallery to see if your tree’s signs match up with those there.
Get in touch with your county’s agriculture commissioner if you think a sample needs to be taken of your plant.
Take preventative action
Some trees may need to be cut down, but many can be saved with the right care. When used at the right time, phosphonate medicines, also known as fungicides, can be very good at stopping Sudden Oak Death. But, the best protection is to not do anything.
The USDA says the following steps should be taken to stop the illness from spreading:
- Cut back and get rid of any infected parts.
- Never buy sick plants from people you can trust.
- Do not move plants that look like they are sick or dying.
- Between plants, clean your cutting shears and other gardening tools.
- Do not let water sit in your lawn or yard, and do not water from above.
Help track the disease
The Midpeninsula Open Space District needs workers to help them keep an eye on Sudden Oak Disease in its local open space preserves so that it does not spread too far.
The group and UC Berkeley work together every year after the wet season for the SOD Blitz Project, a community science event. Volunteers help gather bay laurel leaves that might be affected during the event.
These leaves show if the disease is in the area before oaks and tanoaks get it. They get samples, write down information about them, and then send the samples to a lab to be checked. The findings are made public by UC Berkeley the following year. To see the 2023 results, click here.