UC Master Gardeners of Napa County

Monarchs, and Milkw**d.

By Penny Pawl, UC Master Gardener of Napa County

Every morning when I venture into my garden for my daily walk-through, I hope I will see the golden wings of a monarch butterfly. Occasionally I am lucky, but at this time of year, they are not laying eggs on my milkw**d. They are just passing through on their journey to their summer breeding grounds. When they return to the coast in September, I am more likely to find eggs and babies.

I did recently see a pair of breeding gulf fritillary butterflies. They are also golden but only about half the size of the monarchs. Plantings of passionflower (Passiflora incarnata) have lured gulf fritillaries from the southern U.S. to California.

This morning I finally saw a monarch visiting my butterfly garden. I could not get close enough to see if it was male or female. I also heard that a fellow Master Gardener has 100 monarch caterpillars in her garden. She lives in Carneros so it sounds like the monarchs are working their way up valley. Each and every monarch sighting is important. We need hopeful signs that this valuable creature is making a comeback.

Female monarchs lay their eggs only on milkw**d. Fortunately, some milkw**d species are native to Northern California. Narrow-leaf milkw**d (Asclepias fascicularis) and Asclepias speciosa are the two main types. For egg laying, monarchs prefer the narrow leaf plant. The larvae are willing to eat any milkw**d.

If you want to lure monarchs to your garden, avoid planting Asclepias curassavica. It is a tropical plant with orange and yellow flowers, and it does not die down in the winter. If you have
Ophryocystis elektroscirrha (OE), a parasite, in your garden and your milkw**d does not die down over winter, the parasite can survive to infect the next generation. OE deforms and kills monarchs. Cutting the milkw**d back to the ground in the winter controls the parasite somewhat.

I have read that a female monarch lays about 500 eggs during her six to seven weeks of life. Only about five of those eggs successfully make the transformation from egg to larva to pupa to butterfly. So we need to help them on the journey.

And this brings me to California state law. It is illegal to hand-raise monarch butterflies in our state. To do so, you need to apply for a permit with the state Department of Fish and Game. The reason for the law is that it apparently confuses the butterfly to hand raise them. Some people put large nets over their milkw**d when the larvae are feeding to protect them from birds and insects. At the end of the larva stage, the larvae go in search of the perfect spot to make their pupae. Sometimes you find pupae in the oddest places. I found two this year on pipevine leaves near my milkw**d. I never saw these two in the larval stage.

Growing butterfly-friendly plants like milkw**d will ensure you have plenty of butterfly visitors over the spring and summer. My butterfly garden is busy all day long with anise swallowtails, pipevine swallowtails, honeybees, carpenter bees, wild bees and hummingbirds. You can find a lot of information about gardening for butterflies online.

To learn more about butterfly gardens and attracting monarchs to your garden, register for “Be a Butterfly Angel,” a free Library Talk given by UC Master Gardeners of Napa County, on Thursday, August 6, via Zoom. (Details below.) Watch and learn from the comfort of your home.

Library talk: Join UC Master Gardeners of Napa County and Napa County Library for a free talk on “Be a Butterfly Angel” on Thursday, August 6, from 7 pm to 8 pm via Zoom. Learn how to help support our declining population of Western monarch butterflies. Register to receive the Zoom link.
https://ucanr.edu/search/all?format[live_event]=live_event&sort_by=field_start_date&event_occurrence=1&group[15088]=15088&route=group_events

Tree walk: Join UC Master Gardeners of Napa County for a docent-led tree walk through historic Fuller Park in Napa on Friday, August 7, from 10 am to 11:30 am. Discover some of the many exotic and native trees in this 120-year-old arboretum. Meet at the corner of Oak and Jefferson Streets. Space is limited and registration is required for each participant.
https://ucanr.edu/search/all?format[live_event]=live_event&sort_by=field_start_date&event_occurrence=1&group[15088]=15088&route=group_events

Help Desk: The Master Gardener Help Desk is available to answer your garden questions. Use our online Plant Problem Help Form or email us at [email protected]. Include your name, address, phone number and a brief description of the problem. You can also visit us in person on Mondays and Fridays from 10 am until 1 pm at the University of California Cooperative Extension Office, 1710 Soscol Avenue, Suite 4, Napa.

That Tangled W**d? Cancerwort.

By Cindy Watter, UC Master Gardener of Napa County

May and June are wonderful months for Napa Valley gardens. The flowers haven’t gone to seed; the w**ds haven’t emerged; the tomato plants look promising.

I had an unusually full social calendar in June, so I decided I would be the ambassador for the Good-Enough Garden. This is the garden that is a well-intentioned work in progress. (Note: They all are.)

I was inspired by Margaret Renkl’s children’s book, The W**dy Garden. It is a child’s-eye view of all the life forms in a more natural, less manicured garden space. Beneficial insects, birds and butterflies add to the vitality of a landscape, and I decided I wouldn’t disturb them.

The predictable happened. I walked out on July 1 and saw a new-to-me w**d. It had fuzzy, rounded leaves, with tiny bell-shaped flowers rather like miniature foxgloves. The plant had sent out vines that spread from a central stem. These vines were choking my Jacob Kline bee balm (Monarda didyma).

I had no idea what the aggressor was, but I took a picture with my phone and pulled up the handy iPlant app to identify it. I was the lucky hostess to the round-leafed cancerwort (Kickxia spuria), not to be confused with its near relative, the sharp-leafed cancer wort (Kickxia elatine).

Its alarming sounding name is simple to decipher. “Cancer” means “canker” and “wort” is the Anglo-Saxon name for plant. Long ago people believed that the plant could cure skin irritations, or cankers. “Kickxia” honors two Belgian botanists.
The cancerwort originated in Asia, was carried into Europe (the fuzzy vines could stick to animal fur) and then made is way to North America. Its leaves are simple (not separated into leaflets) and entire (smooth edged). The flower is symmetrical.

Cancerwort is considered an invasive plant. It competes with other plants for nutrients and water. It can crowd out native plants. If it sets seeds, it can multiply rapidly. I remember brushing seeds out of my little dog’s coat. That could be the source of my new invasive plants.

The best way to remove the cancerwort is to dig it out, including the long tap root. I have some work ahead of me. Fortunately, I got a new w**ding knife for Christmas. Also, I will wear gloves—the sap from the plant can be a skin irritant.

I had a good time looking up the different invasive plants in Northern California. The government classifies problem plants by their level of peskiness. First, you have the plain w**d, then the invasive w**d, and finally the noxious w**d.

According to the U.S. Department of Land Management, a w**d is any plant growing where it is not wanted. It can be native, invasive, noxious or not. The legal definition for a noxious plant is “any plant designated by a federal, state or county government as injurious to public health, agriculture, recreation, wildlife or property.”

Many invasive plants can be controlled. You can plant them in large containers, as some people do with Acanthus. Or you can remove their flowers before they set seed, as with butterfly bush (Buddleia). However, when a plant can escape into the wild and easily expand its territory, that can be a problem.

Pampas grass (Cortaderia selloana) and periwinkle (Vinca major) started out as attractive additions to the home landscape. People bought them at nurseries and had no idea they would escape the bounds of suburban life and take over forestland. French broom (Genista monspessulana) is such a problem at Napa’s Westwood Hills Park that there are regular volunteer gatherings to remove it.

My cancerwort is confined to one flowerbed, so it shouldn’t be too hard to remove. If you have w**ds you need to identify, I recommend iPlants, at www.iplants.org.

Workshop: Join UC Master Gardeners of Napa County for a workshop on “Succulents: Out of the Pots, Into the Ground” on Saturday, July 25, from 10 am to noon, at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Learn how to design, plant, and maintain a sustainable garden in your own landscape. Register here.
https://ucanr.edu/search/all?format[live_event]=live_event&sort_by=field_start_date&event_occurrence=1&group[15088]=15088&route=group_events

Library talk: Join UC Master Gardeners of Napa County and Napa County Library for a free talk on “Be a Butterfly Angel” on Thursday, August 6, from 7 pm to 8 pm via Zoom. Learn how to help support our declining population of Western Monarch Butterflies. Register to receive the Zoom link.
https://ucanr.edu/search/all?format[live_event]=live_event&sort_by=field_start_date&event_occurrence=1&group[15088]=15088&route=group_events

Tree walk: Join UC Master Gardeners of Napa County for a docent-led tree walk through historic Fuller Park in Napa on Friday, August 7, from 10 am to 11:30 am. Discover some of the many exotic and native trees in this 120-year-old arboretum. Meet at the corner of Oak and Jefferson Streets. Space is limited and registration is required for each participant.
https://ucanr.edu/search/all?format[live_event]=live_event&sort_by=field_start_date&event_occurrence=1&group[15088]=15088&route=group_events

Help Desk: The Master Gardener Help Desk is available to answer your garden questions. Use our online Plant Problem Help Form or email us at [email protected]. Include your name, address, phone number and a brief description of the problem. You can also visit us in person on Mondays and Fridays from 10 am until 1 pm at the University of California Cooperative Extension Office, 1710 Soscol Avenue, Suite 4, Napa.

Ganoderma, and Solarization.

By Cindy Watter, UC Master Gardener of Napa County

All the signs were there for some time, but I was too distracted to pay attention. First, the cherry tree (never a robust bearer) began to put forth two cherries per season. Next, I started to notice a healthy crop of mushrooms after every rain at the base of the same tree. Finally, last March, I discovered my old familiar Ganoderma fungus adorning the trunk of the same tree.

Some of the fungi were mature looking, but new ones were iridescent in the sun. That’s why their Latin name is Ganoderma lucidum, relating to light. They looked terrifyingly healthy, too. But the tree was certainly dead.

After the usual discussion with my husband (Him: “How do you know it’s dead?” Me: “Remember the willow tree last year?” Him: “How do you know it’s dead?”), I had it whacked down, leaving a stump flush with the soil. What next?

The tree was dead; the fungus was very much alive. It had thoroughly invaded the tree’s tissue, which includes roots. I wanted to clean it up as much as possible so I can plant something else there.

There is no cure for Ganoderma, which is a resilient, opportunistic fungus that attacks the heartwood of a tree, usually by way of damage to the bark. Once you see it on the trunk of a tree, it’s too late. The plate-like projections are actually the fruiting bodies of the fungus that is busy inside the tree, killing it. They are called conks. Cherries, apples, oaks, even pine trees are susceptible to Ganoderma. In the forests the Ganoderma fungus has a purpose—it encourages tree decomposition—but it’s destructive in the garden.

There are two ways to get rid of Ganoderma fungus: toxic and nontoxic. If I were the desperate owner of a Malaysian palm oil plantation, where Ganoderma is running rampant, I would try anything, even chemical fungicides. However, for a backyard frequented by adult and infant humans, birds, butterflies, bees, squirrels, dogs, feral cats, and the itinerant possums, raccoons, skunks and rodents of Old Town Napa, nontoxic is the only way.

My research turned up all sorts of safe remedies, including hydrogen peroxide, cinnamon and baking soda, only there were no specific amounts or concentrations. However, I also learned about solarization of the soil from The New Sunset Western Garden Book. Solarization is the technique of using the sun to purify your soil.

First, I will have someone sturdier than I am remove what’s left of the stump and roots. Then I will buy some UV-proof 4 Mil plastic sheeting. Next, I will rake up any twigs or rocks that might keep the plastic sheeting from lying flat. Then I will dig a trench around the area I want to solarize. After that, I will soak the soil with water to a depth of 12 inches.

And now for the fun part: I will place the plastic sheeting over the affected area and bury the edges in the trench. The idea is to keep the sheeting as flat as possible on the soil. The sun will heat up the soil—rather like what goes on in a greenhouse— and kill the fungus. Eight weeks should do it. The hottest months of the year in Napa are July through September, so my timing is good.

I will wait until winter to plant a replacement tree, and the winter rains should give me a clue—mushrooms—as to whether the soil has been decontaminated. I will be careful not to poke holes in the plastic, which would defeat the solarization. Incidentally, solarization is an excellent way to kill w**ds.

The best way to avoid Ganoderma fungus is not to have it in the first place, meaning practice prevention. This includes sufficient watering to keep your tree strong and healthy. Dig trenches if necessary so you don’t have standing water. Mulch your trees. Clean your pruning tools after every use.

In general, the fungus attacks trees that are in some sort of distress, so take care of them. Don’t scrape them with rakes or run into them with lawnmowers and break the bark. That is the usual way fungi attack trees.

I am in my yard a lot, bird- and butterfly-watching, but I didn’t keep an eye on that cherry tree. The Ganoderma was probably brewing for five years. That’s about how long it takes for it to kill a tree. A dead tree is a dangerous tree, too. When it inevitably falls over, it can do a lot of damage.

Photos by the author.

Workshop: Join UC Master Gardeners of Napa County for a workshop on “Succulents: Out of the Pots, Into the Ground” on Saturday, July 25, from 10 am to noon, at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Learn how to design, plant, and maintain a sustainable garden in your own landscape. Register at our. public website.

Library talk: Join UC Master Gardeners of Napa County and Napa County Library for a free talk on “Be a Butterfly Angel” on Thursday, August 6, from 7 pm to 8 pm via Zoom. Learn how to help support our declining population of Western Monarch Butterflies. Register to receive the Zoom link at our public website.

Tree walk: Join UC Master Gardeners of Napa County for a docent-led tree walk through historic Fuller Park in Napa on Friday, August 7, from 10 am to 11:30 am. Discover some of the many exotic and native trees in this 120-year-old arboretum. Meet at the corner of Oak and Jefferson Streets. Space is limited and registration is required at our public website for each participant.

Help Desk: The Master Gardener Help Desk is available to answer your garden questions. Use our online Plant Problem Help Form or email us at [email protected]. Include your name, address, phone number and a brief description of the problem. You can also visit us in person on Mondays and Fridays from 10 am until 1 pm at the University of California Cooperative Extension Office, 1710 Soscol Avenue, Suite 4, Napa.

Join Master Gardeners to learn how to integrate succulents into your garden plan.
Master Gardeners will explore the ecological and environmental benefits of succulents in your garden. Learn how to create a beautiful garden by putting these amazing and versatile plants to work, transitioning them from pots into the soil.
Reserve your spot at

https://www.eventbrite.com/o/uc-master-gardeners-of-napa-county-64001877853?aff=ebdsshcopyurl

Native Bees

They come in many sizes— from very tiny to almost 2” long. They come in many colors and are not always striped. The males don’t have stingers and not aggressive (because they have no hive to protect). Females have stingers but are not aggressive either. There are 1600 different kinds of native bees in California.

Only the honeybee (who was brought to America in 1622 by the European colonists) builds enormous hives with well-organized family groups.

Most native bees lead solitary rather than social lives, with each female constructing and provisioning her own nest without any help from other members of her species. Single moms, if you will.

Beyond the honey bee: Learn more about California native bees:
https://arboretum.ucdavis.edu/blog/beyond-honey-bee-learn-more-about-california-native-bees

More about honeybees: https://canr.udel.edu/maarec/honey-bee-biology/the-colony-and-its-organization/

Photo collage of native bees

Dahlias

Did you know that before horticulturalists began breeding dahlias for ornamental purposes, the plants were grown for food by the Aztecs, who ate the tuberous roots?

The Napa Master Gardens told us that “the roots are still used in Oaxacan cooking, and an extract obtained from them is a common addition to Central American beverages. Don't go chopping up your dahlia tubers just yet, though. The ones you get from your local nursery have been cultivated for appearance, not flavor, and will likely not be to your taste.”

Dahlia flowers are known as "composite" blooms with not one but many flowers. “The multiple small flowers, called florets, are often mistakenly identified as petals. Lacking much fragrance, the plants use these showy blooms to attract pollinators.”

Dahlias come in many forms; there are over 50,000 types. They range from dainty pin-cushion size to glorious dinner-plate size. They can be short, medium or tall-stemmed. Some bloom as early as June and late blooming varieties may not bloom until September. They can be any color of the rainbow, minus blue.

You can find them now, likely blooming, at nurseries. Or you can plant tubers in mid March, once danger of frost has passed. Plant them in a location that gets morning sun and is protected from hot afternoon sun. They like well-drained, acidic soil.

More info on growing dahlias:https://ucanr.edu/sites/mgslo/files/303934.pdf