Green Wednesday: Cunning Coyotes and a Deadly Tree Disease
Green Wednesday: Gardening and Ecological Insights
Every Wednesday Napa Valley Features brings you Green Wednesday, featuring articles from environmental voices and the UC Master Gardeners of Napa County. These contributors share research-based horticultural advice, insights on sustainability and climate topics relevant to our region.
Summary of Today’s Stories
In "California’s Cunning Coyotes," Kathleen Scavone explores the biology, behavior and cultural significance of coyotes in Napa County, from their eerie calls to their crucial role in maintaining ecosystem balance.
“Coyotes play a significant role in the ecosystem and farmlands since they keep down agricultural pests.” — Kathleen Scavone
In "The Facts About Deadly Phytophthora," Gayle Nelson explains how a fatal fungal disease claimed her beloved black walnut tree and outlines what gardeners should know about diagnosing and managing Phytophthora.
“Phytophthora is a terminal diagnosis in a tree of this size.” — Gayle Nelson
California’s Cunning Coyotes
By Kathleen Scavone
NAPA VALLEY, Calif. — The sound of a pack of coyotes when the dark night sky hasn't yet given way to copper-colored sunrise is pure enchantment. Who hasn't heard the call of the wild and marveled at all that goes on in the twilight times? Don't you wonder what coyotes see in their nocturnal wanderings? What do all of those vocalizations, howls and yips mean?
According to the Nature Conservancy's Cool Green Science website, coyotes can vocalize in a variety of ways. A yip-howl is believed to allow coyotes to bond in their family's group. When coyotes howl and bark separately, they may be indicating agitation from finding the scent marks of other groups of coyotes, the scent of a dog or other intrusion onto their territory. It is believed that coyotes’ howls contain sounds distinct to each individual and that they can recognize information conveyed in each other's howls, such as “all is well” or agitation that specifies intruders need to stay away.
Some indigenous groups are called coyote “song dogs” due to the barks and calls the animal makes. Various indigenous people have myths and stories in abundance about the cunning critters. Many Native American groups held Coyote as a prominent trickster character with its attributes of flaws and foibles held by many humans. The Wappo of Napa Valley, along with other California tribes such as Pomo, Yokut, Chumash, Karok, Maidu and many more told stories of their sacred character where Coyote was depicted with both creative and divine powers.
iNaturalist Napa County explains that the Knoxville area provides coyote sightings, but you don't have to go too far from home to view these highly adaptable mammals. Both the Napa County Regional Park & Open Space District and the Land Trust of Napa County share how plentiful wildlife in the parks and open space lands is across the county.
Coyotes (Canis latrans), found across North America, can also be seen and heard in daylight hours. My husband watched one as it trotted by the field he was disking with his tractor, while those of us taking a Pepperwood Preserve hike sighted one in the grasslands as he was hunting for voles and mice. My south-of-Middletown critter cam often picks up photos of a coyote as he slips down to the creek for an evening drink.
Coyotes play a significant role in the ecosystem and farmlands since they keep down agricultural pests such as mice and rabbits, which also keeps rodent-borne illnesses in check.
Coyotes are highly adaptable, making your chances of spotting one pretty good. Native to California, they are found throughout most of the state in varied terrestrial biomes, such as grasslands, deserts, forest, scrub, mountains and chaparral, where they consume rabbits, eggs, reptiles, rodents, plants and more. These intelligent and cunning creatures don't only thrive in unpopulated lands, but they have adapted to thrive in urban areas, agricultural spaces and rural areas, as well.
Since coyotes are wild and adaptable, many people have feared them over time as they seem to get too close for some folks’ comfort. Fear of the unknown can predominate; therefore, you can take steps to keep them away by making loud noises if you come into contact.
The Department of Fish and Wildlife has an informative YouTube video called CDFW-Wildlife Watch to aid in coexisting with coyotes and other wildlife. The video explains that for safety's sake, don't feed wildlife and keep pet food out of the reach of wild animals.
These animals’ beautiful coats are gray, brown and tan mixed together with a bit of black. Coyotes’ black-tipped tail is bushy and often drapes downward. Smaller than gray wolves and larger than foxes, coyotes usually weigh 10-35 pounds and are 18 to 23 inches tall at the shoulder.
Actor Peter Coyote, who is on the Advisory Board of Project Coyote, advocates for this flagship species since it is culturally significant and has faced threats over time to have it eradicated. The team at Project Coyote advocates for wild carnivores out of respect for human and non-human animals. They hope to build a more compassionate world though their work and encourage diversity. Like a lot of folks, they find themselves in awe at nature's beauty and thrive on cultivating joy through connections with the natural world. As Ansel Adams said, "I believe the world is incomprehensibly beautiful — an endless prospect of magic and wonder."
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Kathleen Scavone, M.A., retired educator, is a potter, freelance writer and author of “Anderson Marsh State Historic Park: A Walking History, Prehistory, Flora and Fauna Tour of a California State Park,” "People of the Water" and “Native Americans of Lake County.” She loves hiking, travel, photography and creating her single panel cartoon, “Rupert.”
The Facts About Deadly Phytophthora
By Gayle Nelson, UC Master Gardener of Napa County
NAPA VALLEY, Calif. —The tree is 50 feet tall with a 30-foot-wide crown, a majestic and statuesque presence in my garden. I just love it.
And it is fatally ill. Truly, fatally. As a Master Gardener, that is the last thing I wanted to learn when I spotted bright orange blotches on the trunk in January when all the leaves were gone. I will have to remove it someday. I am already imagining the empty space it will leave. Phytophthora is a terminal diagnosis in a tree of this size.
My tree is a black walnut, about 45 years old. It has provided shade in the garden, limbs for swings and branches for children to climb. It has produced walnuts for squirrels and for homemade nocino, the Italian walnut liqueur.
Black walnut (Juglans nigra) is a hardwood tree native to the east and central United States. More likely, the black walnut in my garden is Juglans hindsii, also known as Northern California walnut, Hind's black walnut or Claro walnut. It is endemic to Northern California, ranging from the San Joaquin Valley to the California coastal ranges.
You can recognize the Northern California walnut by its short, thick black trunk and lack of branches in the lower 10 to 40 feet. Its immense crown can span 60 feet, making it a fantastic shade tree in summer. Its leaves are 1 foot in length with 13 to 21 leaflets. The tree is resistant to frost and does not leaf out until late spring, when the soil is warm. This description fits my black walnut precisely.
Black walnut is allelopathic, meaning it emits compounds that affect the plants around it. In the case of black walnut, it produces juglone in its roots and leaves. This toxin can harm other organisms, giving the tree a competitive advantage. In fact, nothing grows underneath my tree.
Due to its nematode resistance and drought tolerance, Juglans hindsii is a commercially important rootstock for the English walnut. The tree has certainly thrived in its western placement in my garden, its canopy providing welcome shade all summer. But enough about black walnut. Let’s talk about the diagnosis: Phytophthora.
Last January, bright orange patches on the trunk of my tree caught my eye. At first I thought they might be a kind of orange fungus that colonizes dead trees. But my tree is alive
I pulled the “California Master Gardener Handbook” off my shelf and looked up diseases of walnut trees. Through examination of symptoms and signs, I began the process of elimination, using a list of walnut diseases on the University of California IPM site. The one disease I could not eliminate was Phytophthora, primarily because of the orange streaks and the lack of vigor of the branches near them. Photos from UC IPM confirmed the orange markings as a sign of the disease.
Phytophthora root and crown rot is a fungal disease that infects many types of plants, including black walnut trees. The condition can affect the roots, the crown or both. The disease thrives in wet, poorly drained soil and can cause the roots of the tree to rot, leading to a decline in overall health and eventual death. Symptoms in black walnut trees include yellowing leaves, wilting foliage, stunted growth and cankers at the base or on the trunk.
Although my tree does not have cankers or exhibit signs of root rot (yet) and it never has been in saturated soil, there is marked defoliation near the orange spots. I consulted a certified arborist, who sadly confirmed my diagnosis.
Phytophthora is somewhat treatable in much younger and smaller trees, and walnut trees in commercial orchards can benefit from certain fungicides when Phytophthora is present. My old tree is too large to consider treatment of any kind.
The tree will decline over the next few years. My dilemma is whether to watch it slowly perish or remove it now and plant another tree — or more likely three trees — in its place. The likelihood of my living long enough to see a replacement tree reach that size is pretty low.
Fortunately for others considering tree replacement, PG&E publishes a brochure on planting the right tree in the right place. It lists and illustrates a wide variety of trees suitable for gardens large and small. Primarily designed to help homeowners select trees that will be planted near powerlines, the document nonetheless suggests tantalizing specimens. I’m going to look for quick-growing ones for when the time comes. What would you do?
Events
Workshop: Join UC Master Gardeners of Napa County for a workshop on “Welcoming Pollinators Into Your Garden” on Saturday, Aug. 23, from 10 a.m. to noon at the University of California Cooperative Extension, 1710 Soscol Ave., Napa. Monarchs and other pollinators are in serious decline. Learn what you can do to help by creating habitat to support these essential creatures. Registration required.
Library Talk: Join UC Master Gardeners of Napa County for a talk on “Compost: It’s Alive!” on Thursday, Sept. 4, from 7 to 8 p.m. via Zoom. Learn how decay breeds life in your garden and how you can harness the power of compost. Register to receive the Zoom link. Note that the meeting will lock and allow no further entry at 7:15 p.m. Please join prior to 7 p.m.
Tree Walk: Join UC Master Gardeners of Napa County for a docent-led tree walk of Fuller Park in Napa on Friday, Sept. 12, from 10 to 11:30 a.m. Historic Fuller Park is an arboretum with many exotic and native trees planted over the past 120 years. Meet at the corner of Oak and Jefferson streets in Napa. Registration is required for each participant.
Become a Master Gardener Volunteer: UC Master Gardeners of Napa County is now accepting applications for the Class of 2026. Visit napamg.ucanr.edu for more information and register to attend a mandatory information session for applicants. Applications are due by 5 p.m. on Sept. 25.
Help Desk: The Master Gardener Help Desk is available to answer your garden questions on Mondays and Fridays from 10 a.m. until 1 p.m. at the University of California Cooperative Extension Office, 1710 Soscol Ave., Suite 4, Napa. Or send your questions to mastergardeners@countyofnapa.org. Include your name, address, phone number and a brief description of the problem. For best results attach a photo.
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Gayle Nelson is a UC Master Gardener of Napa County.
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Very well written, informative article!!!!