- Author: Kathy Keatley Garvey
And curious photographers.
Last weekend we spotted cottony cushion scale, Icerya purchasi, infesting the twigs and branches of our Nandina (Nandina domestica), planted 22 years ago. This scale insect is more commonly found on citrus crops and Pittosporum, but there it was.
It's a native of Australia and apparently made its way to California on acacia plants around 1868 or 1869, and began infesting citrus groves in southern California. It's now found throughout the world, wherever citrus is grown. Pick it up and it's as light as a feather and soft as cotton.
If you look closely at a mature cottony cushion scale (hermaphrodite), you can see that it's reddish brown with black hairs. It produces a ridged white egg sac encasing hundreds of brilliant red eggs--the color of pomegranate kernels.
"Like other scales, cottony cushion scale decreases the vitality of its host by sucking phloem sap from the leaves, twigs, branches, and trunk," according to UC IPM. "Feeding can result in defoliation and dieback of twigs and small branches when infestations are extremely heavy. Heavy populations can severely reduce the yield of citrus trees. Like soft scales, cottony cushion scale excretes honeydew, which is usually accompanied by blackish sooty mold growth and ants."
"Cottony cushion scale has two to three generations a year," UC IPM tells us. "Unlike most other scales, it retains its legs and its mobility throughout its life. Cottony cushion scale completes its life cycle in three months during warm weather conditions."
Its most famous natural enemy is the vedalia beetle, Rodolia cardinalis, introduced from Australia in the 1890s to save California's citrus crops. Vedalia beetle vs. cottony cushion scale--this is a clear-cut case of successful biological control. Vedalia beetles are distinguished by their darker red domes with splotchy black markings.
Another natural enemy is the parasitic fly Cryptochaetum iceryae, which lays its eggs inside the cottony cushion scale. "It deposits one to four eggs inside each second-instar, third-instar, or adult female scale body," UC IPM points out. "The eggs hatch into larvae that feed within the scale." (See more information on the UC IPM website)
Interesting that we've never found the cottony cushion scale on our nearby tangerine and lemon trees. "Marked Safe from Cottony Cushion Scale."
For now!
By Penny Pawl, U. C. Master Gardener of Napa County
For the last three years I have been battling gophers in my garden. They have pulled artichoke plants down their hole and last summer took out my peppers and eggplants. A young fig tree had only a chewed-on place where its roots had been. In desperation I bought wire cages to plant in.
In my backyard the gophers have taken out every Liriope (mondo grass) and made massive tunnel systems. I stepped in one and my foot went in up to my ankle. I could see inside the tunnel. I left it open but it was closed the next morning so I know there is still a gopher moving actively under my garden.
I know many people are successful using traps to catch and kill gophers but I don't have the intestinal fortitude for that. So over the years I have resorted to other methods. On occasion I have put things down their runways to chase them away, including lighted road flares, dog manure and a hose of running water. I also chased one gopher out of his hole and used a pitchfork to end his life. But none of these actions got rid of the devils.
And what happens to all that soil they moved? I occasionally see a pile, a tell-tale sign of gopher activity, but I don't see big piles.
Their tunnels can affect plants by allowing water to flow underground and by drying out roots that reach that level.
Since gophers have decimated whole areas in my garden, I have started to research just what plants they won't eat. I also had my vegetable beds lined with hardware cloth to keep them out. That approach seems to be working but they do burrow around the beds seeking a way in.
I found a website that has gathered opinions on what plants are gopher proof (https://www.mostlynatives.com/plant-characteristics/gopher-resistant). It lists native plants that seem to be uninviting to gophers. I have also found a few non-natives that don't seem to attract them. If a plant is not to their liking, they move on.
Unlike moles, which are carnivores, gophers are vegetarians and live on many kinds of plants. Once they leave the nest, they are solitary animals and only meet to mate. Their time in their tunnels is spent building up their larder for winter. Their tunnels may be 200 feet long. My husband once dug a gopher out that had gone into a bed we were preparing. He was about three feet deep in his den. They dig deep and wide.
Most plants that don't taste good to a gopher also tend to be drought tolerant so you can kill two birds with one stone. The plants in my garden that gophers have not touched are nandina, fortnight lily, lily of the Nile, daylilies, salvias, hellebores, society garlic, monkey flower and verbascum, to name a few. I plan to use more of these in my landscape.
Recently, my gophers have been busy in a new area. They have almost completely taken out my mondo grass. When they finish, I will plant something they don't like.
I have started to use underground buzzers to drive gophers away from plants they eat. They were pulling the roots off my milkweed, so I set buzzers up on either side. The noise-making devices seemed to stop them, so I have invested in a few more to put around the yard.
Next workshop: “Cool-Season Vegetables: Now is the Time to Plan and Start” on Saturday, August 10, from 9:30 to 11:30 a.m., at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Repeated on Sunday, August 11, from 1 p.m. to 3 p.m. in Yountville. For more details & online registration for the Napa workshop: http://napamg.ucanr.edu. Or call 707-253-4221. For the Yountville workshop, go to Online Yountville registration or telephone the Parks & Recreation Department at 707-944-8712.
The UC Master Gardeners are volunteers who provide UC research-based information on home gardening and answer your questions. To find out more about upcoming programs or to ask a garden question, visit the Master Gardener website (http://napamg.ucanr.edu) or call (707) 253-4221 between 9 a.m. and noon on Mondays, Wednesdays or Fridays.
- Author: Kathy Thomas-Rico
I was just given some really wise advice from a dear friend: Find the silver linings. Applying that to the state of my garden in the depths of a dry, windy winter makes for a colorful crazy quilt of good things. Here goes:
- Seeing red: Right now, the eye-catching spots in my yard are red. Tucked among the greens are Nandina domestica 'Firepower', which live up to their name when the sun hits them. The other reds are the berries hanging from the toyons (Heteromeles arbutifolia), firethorn (Pyracantha angustifolia) and asparagus ferns (Asparagus densiflorus 'Sprengeri'). The birds love the berries, too.
- Lack of leaves: The winds of December took most of the leaves, and now I have an unhindered view of a big blue sky. It’s a great contrast to the bare branches and occasional evergreen.
- Orchids: OMG, have you seen the orchids? They are everywhere, in full, beautiful bloom. A local warehouse store is selling a wide variety of Phalaenopsis orchids, beautifully potted, for $15. I succumbed to two, and they will provide us fresh blooms for the next month or two. Even the tough, big orchids I keep outside are ready to bloom. So exciting!
- Citrus: My potted ‘Moro’ blood orange is heavy with fruit, as is our tiny ‘Improved Meyer’ tree, which is in the ground. The bright yellow and orange draw my attention every time I head out back.
- Fight on: Our tree mallow (Lavatera maritime) is the little engine that could. Last spring, this billowy shrub was showing signs of a nasty rust invasion. We cut it to just 6 inches from the ground and crossed our fingers. It now stands 6 feet tall again, and is covered in lovely lilac-colored hibiscus-like blooms. Gotta love a fighter.
- Vernal hors d’oeuvres: Our warm, dry winter has caused many plants to start putting on new growth much sooner than normal. For instance, I have a crabapple in blossom now, and many of our Narcissus bulbs are nearly done blooming. We should expect many more nights with freezing temperatures, which will stunt this new growth. We also should be prepared for a long, wet spring, much like last year. So, I have to admit, I’m looking at our odd weather pattern as a vernal hors d’oeuvre, a nibble of spring. As long as we get some rain soon, it indeed will be a silver lining.