The coast redwood is an iconic native California plant. It thrives where marine fog and cool temperatures create a moist, lush forest environment. It's also commonly planted in Fresno County communities, where it has adapted to irrigated landscapes, growing tall and defining city skylines.

Why has the coast-loving conifer been planted so widely in areas where summers are dry and temperatures routinely top 105 degrees?

“There's something magical about redwoods,” said UC Master Gardener Tim Sullivan, who lectured about the trees July 8 at the Woodward Park Library in Fresno. “They're beautiful.”

Sullivan researched redwoods online, visited the UC Davis Arboretum redwood forest, and traveled to Redwood National Park near the Oregon border to gather information for his presentation. All the UC Cooperative Extension advisors, UC professors and national park rangers he interviewed recommended Coast Redwoods not be planted in the Central Valley.

However, local homeowners and landscapers disagree. With the trees so popular in Fresno County, Sullivan developed suggestions for coast redwood care that mimic the trees' natural environment.

In the North Coast and at the arboretum, he said, the forest floor is thickly mulched with redwood needles that have dropped from the trees, along with fallen trees, branches and twigs.

“In Fresno, we tend to rake everything up,” he said. “At least leave the needles, and add grass clippings and water to break them down. The mulch builds soil and will also keep the roots cooler.”

The soil in natural settings are further supported by lush green plants, such as redwood sorrel, trillium, Douglas iris and a variety of ferns. It may take experimentation to determine what shade-loving plants will grow underneath coast redwoods in warm interior valleys. Sullivan suggested one option is gray sedge, Carex divulsa, which he saw growing under trees at the UC Davis Arboretum.

In forests, the community of trees form a web of life, interlocking roots with each other and other plants, together staving off coastal winds.

“Redwoods do not like living alone,” Sullivan said. “Their roots stay in the top two- to three-feet of soil and stretch out 50 feet in all directions from the trunk. They do well in irrigated lawns and parks, but next to homes, concrete or artificial turf, they may become unstable.”

In foggy coastal areas, moisture collects on redwood needles and continuously drips down from the canopy to the forest floor.

“The trees have evolved this incredible self-irrigation system that waters the trees and the understory plants,” Sullivan said.

In the Central Valley, the trees will need a lot of water. Provide regular surface irrigation and once-a-month deep application of water, reaching at least two feet below the soil surface, Sullivan said.

For more information on growing coast redwoods in the Central Valley, see these UC Cooperative Extension resources:

Coast Redwoods as Landscape Trees by Michelle LeStrange, UC Cooperative Extension horticulture advisor emeritus, Tulare County

Growing Coast Redwoods by Emma Connery, UC Master Gardener Program Coordinator, Contra Costa County

Coast Redwood Tree Problems by Ed Perry, UC Cooperative Extension horticulture advisor emeritus, Stanislaus County

 

 

Looking for a salvia that's something out of the ordinary? Salvia Africana-lutea, or beach sage, is just that. Rarely seen in our area, beach sage is a very tough, drought tolerant shrub.

Fragrant gray-green foliage is slightly ruffled and almost succulent looking. Rusty orange flowers that quickly fade to brown begin in early spring and continue sporadically through fall.

In addition to their unique color, flowers have a curious “withered” appearance even when fresh. Purple-tinged papery calyces remain attractive after petals fall, providing almost year-round interest. Native to coastal areas of South Africa, beach sage prefers sandy, loose soil.

Plant in full sun to part shade. Water occasionally and feed with an annual top-dressing of compost. Eventually reaching 4 to 6 feet tall, it should be trimmed back by at least a third in late spring to encourage new basal growth. Hardy to 20 degrees Fahrenheit. Attractive to pollinators. Hard to find in garden centers but easily available by mail order. All in all, this is one eye-catching sage.

Introduction

Have you ever walked through your roses and seen a hole in the emerging buds filled with a black gooey substance? Well, the tobacco budworm is at work, and yes, on your ROSES. The tobacco budworm is the larval form of the adult moth, Helioithis virescens (scientific name). The budworm is actually a caterpillar, developed from the eggs of the adult moth.

The tobacco budworm will bore into the flower buds. Look for the caterpillar or its frass inside the buds. The caterpillar is under one-inch long, green, yellow or brown with white or black markings. The adult moth has a wing span of about 1½ inches and is brown/green in color.

According to the University of California, budworms feed on geraniums, petunias, snapdragons and roses as well as a lot of agricultural crops, fruits and vegetables, and many horticultural plants. Evidence of their arrival are tiny round or oblong 1/16-inch holes in flower buds, 1/8-inch holes in leaves and blooms, and black seed-like droppings. Flowers that open after budworm infestation have damaged petals and a budworm can destroy several flowers per day. The plant may cease flower production completely if severely infested. The budworm may move on to consume leaves and foliage also. The budworms peak in late summer. When mature, the larva drops to the ground and pupates in the soil. They can have 2 to 4 generations in a season, overwinter in the soil, and emerge as a moth again during the next growing season.

Management

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical management

According to Washington State University and the University of California, avoid use of broad-spectrum insecticides which kill natural predators of garden pests as well. Predators of caterpillars include birds, spiders, big eye bugs, damsel bugs, minute pirate bugs and parasitic wasps. Planting herbs such as parsley and coriander or flowers such as sweet alyssum provides a habitat for predatory insects.

Manage weeds in and around gardens to remove the habitat and alternate food sources for the tobacco budworm.

Monitor plants closely for damage. Handpick and destroy larvae and infested buds on roses. Hand pick caterpillars or prune out and promptly dispose of infested buds or rolled leaves (often hiding caterpillars within).

Scout for larvae at dusk, when they are most active. Check for actively feeding larvae, small holes in buds and flowers, and caterpillar droppings (frass or feces) associated with damaged buds.

Chemical management

Tobacco budworm, particularly mature larvae, is reported to be resistant to many common garden insecticides. Manage with cultural controls whenever possible.

Bacillus thuringiensis (Bt) is somewhat effective if applied when eggs or damage are first noticed. However, Bt must be consumed by young, actively feeding larvae and only works where the young larvae are feeding on the SURFACE of the plant. Bt is NOT effective against larvae feeding within buds and will not provide reliable control of mature larvae.

Damage is usually not severe and treatment with pesticides not generally necessary. Leaf-feeding caterpillars can be reduced with the microbial insecticide Bacillus thuringiensis or the insecticide Spinosad. These materials will be most effective when caterpillars are small, however caterpillars within buds are unlikely to be killed. Damage may not be noticed until after caterpillars are full grown and no longer vulnerable to insecticide applications.

References

https://ipm.ucanr.edu/PMG/PESTNOTES/pn7466.html   

https://entnemdept.ufl.edu/creatures/field/tobacco_budworm.htm

 https://www.gardeningknowhow.com/ornamental/flowers/roses/budworms-roses.htm

https://ucanr.edu/datastoreFiles/268-758.pdf

https://hortsense.cahnrs.wsu.edu/fact-sheet/rose-tobacco-budworm/

Beth Linder Carr has lived among blue oaks in Auberry for nearly 35 years. There are dozens on her 10-acre property, but the one in particular she and her husband prize is a majestic specimen in the center of their circular driveway. They were dismayed when two huge limbs crashed down unexpectedly within the last 18 months.

“I thought it might not leaf out at all this year, but it's in full leaf now; its formerly huge canopy now patchy and uneven,” Linder Carr said. “Whether it's just old and dying, or the drought has contributed to its decline — or a combination — is unclear to me.”

Linder Carr brought her questions to a field day June 3 at the McKenzie Preserve near Prather, one of eight preserves owned by the Sierra Foothill Conservancy, where UC Cooperative Extension and other scientists shared early results of ongoing studies of blue oak trees.

Blue oaks are a keystone species in the foothill ecological zone, said Billy Freeman, Sierra Foothill Conservancy rangeland manager. They sequester carbon, provide wildlife habitat, support foothill biodiversity and are beautiful. Research underway at the site will inform landowners about how land management may impact the ecosystem, particularly considering the warming California climate.

The study is divided into two plots: one treated with short term, high density cattle grazing, and the other managed with continuous moderate grazing.

“A few years of monitoring the trees on these sites will help us understand which grazing practices best support blue oaks,” Freeman said.

Sokaina Alkhafaji is recording changes in oaks for the National Ecological Observatory Network. Dendrometers, aluminum bands rigged with small springs, were installed on 30 trees to accurately measure the incremental increase in tree diameter year to year. Each month, researchers visit the plot to document the timing of seasonal changes, such as bud break, leaf emergence, canopy fullness and acorn production.

“Right now, we don't know how oaks are doing. Does grazing management need to be changed? Do we need to cage seedlings?” she said.

The canopy areas and tree trunk diameter are documented in the first year of the study and will be repeated in five to 10 years. She visits the oaks twice a year. In the spring, her study documents tree vigor and mortality and the number of seedlings sprouting beneath tree canopies.  In the fall, she counts acorns, measures shoot growth and confirms whether the seedlings found in the spring are still growing.

“Our goal is to monitor the trees at least 10 years in the four places,” she said.

The monitoring protocol is designed to be easy for foothill residents and land managers to replicate. For example, shoot growth is determined by twisting a pipe cleaner on twigs on the north, south, east and west sides of the tree, then returning to those twigs each year to measure new growth. Acorns are estimated by counting acorns in the oak canopy for a set period of time – such as 20 seconds – and then recording the number.

“Our key goal is making monitoring as consistent, time efficient and as cheap as possible,” Ozeran said.

The field day resonated with Linder Carr. As soon as she got home, she said, “I started looking at the trees with new eyes. Our big center oak, for instance, has much bigger girth than any of the trees on the preserve, and so it would be interesting to measure some of ours.”