Palm Canyons

After a couple of extreme drought years, Southern California deserts are dry, dry, dry! This, along with a mid-April visit that was well-past any winter rains, impacted our wildflower viewing. We saw flowers, but not the massive displays and variety of two years ago. Still, the creeks through Palm Canyon and Andreas Canyon near Palm Springs flowed with water, and the palms looked healthy and green.



Panoramic view of Palm Canyon oasis surrounded by dry hills

My folks and I drove up to Palm Canyon, identifying Honey Mesquite, Creosote Bush, Desert Lavender (no blossoms), Brittlebush, and California Fan Palm along the way. We enjoyed the view from above – the large oasis of palm trees below, and the long line of palms that follow the creek up the canyon. From the shady benches provided by the Trading Post, we savored cold water, and observed the hummingbirds, squirrels, and lizards that flitted about in the hot sun.

Hummingbird

Spiny Granite Lizard

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Later, we hiked up Andreas Canyon in the welcome shade and breezes of the palms and cottonwoods lining the creek. For a time, we heard only running water and birds, and no motors or people. Here we identified Yerba Santa, Lax-flower, Cat’s Claw Acacia (also called wait-a-minute bush, since its recursive spines pull you back), Arizona Ash, and mistletoe on several dead looking trees. We observed many lizards, including a fabulous Spiny Granite lizard basking in the sun.

Hike in Andreas Canyon

After our hike, we dusted ourselves off, freshened up, and headed for the Maracas Restaurant in Palm Springs for delicious Mexican food and conversation. The restaurant is located very close to the new “Forever Marilyn” statue!
 

Apple Preserve

I just returned from a trip to the Southern California, all rested and ready to get back into fray. My folks flew in from Alaska and I flew in from the Bay Area; we joined forces to explore some of the wild places of Southern California, look for desert wildflowers, and enjoy each other’s company. This trip has become an annual event (see Low Desert Lowdown and Mill Creek for past trip reports). One of our favorite places to visit is Los Rios Rancho in Oak Glen, California.

Los Rios Rancho - apple orchard in Oak Glen, California 

I have fond memories of visiting the apple orchard and ranch with my son’s Kindergarten class in the early 1990s. Since then, Los Rios Rancho, along with 2100 acres of open land, has become part of a preserve under The Wildlands Conservancy. Their mission is to preserve natural areas from residential land development. The ranch continues to operate as a working apple farm, growing over 20 varieties of apples. A country store, bakery, restaurant, outdoor picnic area, and barbeque area are part of the operation.

Los Rios Rancho - country store and restaurant 

Our mission was to purchase supplies for our picnic bag – including apple hand pies, and cookies (applesauce and oatmeal, both with raisins). Naturally we needed to test the apple hand pies immediately!

Impromptu picnic - apple hand pies. Yum!

 

Presidio Coastal Scrub

A trail beckoned to us from the battery we were exploring in the Presidio; my folks, husband, and I answered the call. The trail followed the bluff, high above the rocky shoreline, giving us more grand views of the Golden Gate Bridge, ocean, and hills to the north. We were buffeted by the wind, blowing unabated across the ocean. I wished we had brought our walking sticks to help ground us!

Coastal scrub and Golden Gate Bridge (did I mention windy?)

In this area, a coastal dune scrub plant community replaced the coastal dune community of Baker Beach. Low lying grasses and bushes grew along the bluffs, holding them in place, along with a few gnarly trees. You can learn more about the coastal dune scrub plant community on the National Park Website: http://www.nps.gov/prsf/naturescience/coastal-dune-scrub-community.htm

Beckoning trail high on the bluffs



Wild coastal vistas, just a few miles from downtown San Francisco

Many of the flowering plants are small and low to the ground, similar in size to the miniature plants we see growing in the harsh conditions of the tundra in Alaska and Canada. Some of the plants that grow in the Presidio area are common natives and non-natives, others are rare or endangered.

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After a day of exploring the wild side of the Presidio, we headed back to the East Bay for dinner at one of our local neighborhood Chinese restaurants and good conversation. I recommend visiting the Presidio for a day of recreation with family or friends, or studying plant communities that could influence unique garden designs.
 

Presidio Batteries

North of Baker Beach is a whole string of batteries, built into the bluffs overlooking the ocean outside the Golden Gate. They are part of a fortification system constructed over many years. After our picnic at Baker Beach, we drove north a mile or so to park, and then explored.

We enjoyed more beautiful views of Golden Gate Bridge from this different vantage point, and sweeping views of water, hills, and sky. The ocean was choppy, but fleets of sail boats took advantage of the brisk wind. Here the plant community changes from dunes to coastal scrub.



Fortified bunker and the Golden Gate Bridge

The batteries are fascinating in their own right. They are solid and substantial. With my love of wild, desolate places, this would have been a prime assignment. The views of the ocean on one side and the Bay on the other, the Marin Headlands to the north, the rocky and forested coast to the south. But I imagine for most, it would have seemed like the end of the world, and more akin to banishment! You can learn more about the fortification system on the National Park Website: http://www.nps.gov/prsf/historyculture/batteries-east-and-west.htm

Geometric lines of one of the batteries 

Iron door with graffiti

Some of the plants in this area look like weeds. However, after visiting the Wanted Weeds exhibit at this year’s San Francisco Garden Show, I have a new appreciation for weedy plants. As my aunt and I learned, they can “be virtuous host plants, nectar sources, and medicinal”. Maybe it takes a tough little plant to stand guard at the batteries.

Weeds at the edge of the bunker, and pines on the hills

 

Presidio Dunes

April is a beautiful time to visit Presidio of San Francisco, located on the northern tip of the San Francisco peninsula. If you recall from Presidio for a New Perspective in December 2012, my family only recently “discovered” the Presidio area. The area was a military outpost for over 235 years, until it became part of the Golden Gate National Recreation Area in 1994. Parts of the area were used for military purposes, but others were left wild, giving us window into the natural habitat.

My folks, husband, and I visited the Presidio last April, on a beautiful and blustery day, after a long period of gray and rainy days. Our first destination was Baker Beach. We roamed the sandy beach, grateful for our wind breakers, but we did see a bikini or two on the beach! I love this view of the Golden Gate Bridge, so different from the familiar view from Oakland and the Embarcadero in San Francisco.

View of the Golden Gate Bridge from Baker Beach

I was pleased to see that some sand dune areas are roped off from public access, allowing them to revert back to their wild state. The native plants thrive in the shifting sands. This is a great place for a gardener to study and contemplate how to create a dune garden. You can learn more about the natural setting on the National Park Website: http://www.nps.gov/prsf/naturescience/index.htm

 

Protected Dunes at Baker Beach

We ate our lunch among the pines and dunes of the sheltered picnic area, and then wandered along the road looking at plants, military bunkers buried in sand, and vistas of the Bridge and the Marin Headlands.

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Crown Gall

Crown gall is another bacterial disease common in the San Francisco Bay Area. Crown gall is caused by the Agrobacterium tumefaciens bacteria, and is named because masses of galls grow on the roots or root crown of infected plants. Crown gall has a wide host range including 93 families of pome and stone fruits, nuts, ornamental plants, and vines and canes. It was first studied in grape vines in Italy by Fridiano Cavara in 1897. Lack of vigor and poor growth above ground, may indicate a plant is infested with crown gall below ground. You can dig carefully around the root crown to look for evidence.

The A. tumefaciens bacteria can live in soil as a saprophyte (living on nonorganic matter) for a short time, and then invades a host plant through a wound. The bacterium transfers a piece of its plasmid DNA into a plant cell; the genetic code integrates with the plant cell’s genome. Genes on the tumor-inducing (Ti) plasmid cause the cell to divide over and over, forming a tumor. The tumor, or gall, provides shelter and a food source for the bacteria, which live and multiply between the cells of the gall. When the gall deteriorates or breaks off in the soil, the bacteria are released back into the soil. Galls typically form on plant roots, but may grow above ground on trunks and stems.

Bacterial gall growing on root

Crop rotation is an important management tool to break the disease cycle. Other measures include planting crown gall resistant plants, treating the roots of transplants with A. radiobacter (an antagonistic strain), and removing infected plants. Some experts recommend disinfecting tools used for pruning and grafting, but others dispute its effectiveness. To learn more, about crown gall, visit the IPM website: http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/DISEASES/crowngall.html and http://www.ipm.ucdavis.edu/PMG/GARDEN/FLOWERS/DISEASE/crowngall.html.

I was fascinated to learn that this mechanism of using the Ti plasmid of A. tumefaciens to introduce genetic code into a plant’s genome is used to introduce desirable genes into plants and provides the foundation for genetic engineering. This method is used to breed plant strains that are resistant to specific diseases, accelerating the process of selective breeding that humans have been practicing since the beginning of cultivation. This is controversial for many, but lifesaving in areas of the world, like Africa, where plant diseases devastate food crops.

 

Fire Blight

One bacterial disease common in the San Francisco Bay Area is fire blight of the Rosaceae family, which attacks fruit trees, including apple, cherry, apricot, and pear. Fire blight is caused by the Erwinia amylovora bacteria. Its common name reflects that an infected tree looks scorched and blackened as though by fire. Note that bacteria are typically host-specific, so that each tree species has its own E. amylovora pathogen variation (pathovar).

This small stand of Pyrus calleryana ‘Aristocrat’ (Aristocrat Pear)
street trees in Dublin, California looks to be infected with fireblight. 

Fire blight bacteria are spread to flower buds and nectaries in early spring, in humid warm conditions, either through splashing rain or pollinators. The bacteria invade the tissue, causing the blossoms to wilt and collapse. A brown sticky exudate is produced from the damaged tissue and spreads to young shoots. The shoots become infected, blackened, and deformed in a characteristic “shepherd’s crook” shape. The bacteria overwinter in cankers that form in the bark and wood. In the spring, when the temperature and moisture levels are favorable, the cankers ooze with bacteria, and the life cycle begins again. The exudate is splashed onto nearby blossoms, or attracts pollinators, which pick up the bacteria and carry it to new blossoms.

Aristocrat pear blossoms, with fireblight symptoms	Characteristic "shepherd's crook" fireblight symptom
 Bud with symptoms of new fireblight infection	Blossoms with no apparent fireblight infection

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The best treatment is prevention, which includes planting resistant fruit trees and keeping trees healthy and vigorous to ward off infection. You can spray the tree in the spring with copper-based applications, designed to provide a barrier that prevents bacteria from reaching the blossoms, but timing is critical.  The IPM has some guidelines and references for determining the best time to spray, typically based on temperature and humidity. Several sprayings may be needed, since blossoms do not all open at once, and conditions favorable to the bacteria may persist over several months. Once infected, pruning infected limbs or branches 8-12 inches below visible injury can help stop the spread of infection. Some experts advocate sterilizing pruning equipment between cuts; others disagree.

To learn more about fire blight, visit the IPM website: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7414.html. You can also search the site for your specific crop: http://www.ipm.ucdavis.edu/PMG/crops-agriculture.html

Plant Diseases – Bacteria

For the next several posts, I’m taking a look at diseases that affect plants in the San Francisco Bay Area, specifically in the Monera (bacteria) Super kingdom. For sources I’m using FiveKingdoms, Essential Plant Pathology, the U.C. Davis Integrated Pest Management (IPM) website, and information from my plant diseases course at Merritt College in Fall 2012.

Bacteria are categorized as prokaryotes; they have small ribosomes surrounding their nucleoids, but lack a surrounding membrane. Bacteria are small, and live in large colonies that can grow unchecked if conditions are favorable. Genes are organized into thin fibrils, and are passed from one cell to another. Scientists have recently discovered that bacteria communicate chemically. They can live in relative isolation, but participate in a phenomenon known as quorum sensing – when they sense chemically they have enough numbers, they may take action as a group. Learn more: http://www.ted.com/talks/bonnie_bassler_on_how_bacteria_communicate.html

Bacteria are hardy, and can survive in extreme conditions. They move in water, and invade plants through natural opening, such as stomata, or through damaged tissue. Bacteria are dispersed through sticky masses. Bacteria are typically spherical (cocci), rod shaped, or spiral shaped, so, to identify them, you need to test for chemical changes rather than simply observe them under the microscope. Bacteria are critical to healthy soil, and most are not pathogenic.

With our dry, Mediterranean climate, the San Francisco Bay Area does not suffer from many bacterial plant diseases. However, with our wet, rainy season, temperate climate, and coastal fog, we do have conditions part of the year that are favorable to bacteria.