Online Site Inspections with Corona Virus: A New Paradigm?

Posted on April 24, 2020 by landscapeexpert

The corona virus and resulting stay at home order has prevented me from scheduling or attending site inspections. I require site inspection for most forms of consulting work, including as a consulting arborist or expert witness.

Tree failures, health and risk assessment
Tree inventories
Tree and nursery appraisals
Tree roots and infrastructure damage.
Landscape appurtenances creating trip and fall hazard.
Obscured landscape hazards, grade changes
Irrigation operation, maintenance issues

A client wanted me to attend and observe asphalt paving taking place adjacent to an 80 year old Torrey Pine. I had previously consulted on preserving this tree during construction on an adjacent property. The client was repaving his driveway on the alley, the pine is right on the edge of the paving.

Due to California stay at home orders, I informed the client I could not be present to observe the paving to make recommendations, so we used the Facetime app and did an online site observation whereby I watched in real time as the work was being performed. I was able to give the client recommendations in real time.

Moistened towel protect surface roots

He was concerned about root damage, and rightly so. Some of large buttress roots would be impacted by the paving. Instead of cutting, I recommended covering the roots with wet towels, fabric etc, then placing moistened sand base, then pave over the roots.

Moistened sand placed over protected roots

As terrible as it is, the corona virus has created many new ways for industries to re-invent how they do their business. This was the first time I have attempted on online site inspection and it worked! This may not be applicable for the types of investigations I perform, but there is a great new tool I can use for certain types of investigations during stay at home and even beyond.

Asphalt paving over protected roots

The financial savings for the client are obvious. Travel costs for me to travel to Los Angeles, Orange or Inland Empire typically range from $500 to $1000 or more if hotel stay is required.

Not all inspections can be performed remotely. Forensic investigations that require measurements, excavations, sampling, testing etc may not be applicable.

Since this is new to me, it will take some real time client cases for me to determine how and when I can utilize this new tool.

Old Growth Redwood Destruction Continues

Posted on April 21, 2020 by landscapeexpert

I read an L.A. Times article discussing ongoing logging of redwoods in Humboldt County. In a battle spanning several generations, tree sitters and eco-activists are putting their bodies on limbs in redwood tree tops to prevent logging.

This is not the first time tree activists have climbed hundreds of feet up old growth redwoods to prevent logging the tree and surrounding trees. It reminded me of a remarkable novel I read called “The Overstory” by Richard Powers. The novel is about people and their interaction with and the affect specific trees and forests.

It primarily focuses on loss of old growth redwoods and firs in the pacific northwest and activists actions to prevent tree and habitat loss. However, the novel was historical, taking place several decades ago. Yet it appears old growth logging in Humboldt county continues to in present.

I recently visited, camped and explored the Jedediah Smith State and National Redwood park, not far from where present day logging takes place. For me, the thought of logging off trees that are hundreds to over a thousand year old is difficult to accept.

We have commercial redwood farms for harvesting lumber. Of course, it does not possess the grain, size, color and characteristics of true old growth redwood trees. If we want future generations to be able to view and experience the incredible creation of a true, old growth tree, we MUST stop logging and preserve this resource.

Joshua Tree Extinction by End of Century?

Posted on April 14, 2020 by landscapeexpert

I just read an article in the Los Angeles Times about a potential listing of the Joshua tree as an endangered species. The western Joshua tree, Yucca brevifolia, is one of two genetically distinct species that occur in California. It range extends from Joshua Tree national park westward along the northern slope of the San Bernardino and San Gabriel mountains, northward along the eastern flank of the Sierra Nevada and eastward to Death Valley.

Approximately 40% of the western tree range is on private land, the eastern range is centered in the Mojave National Preserve and eastward into Nevada.

After decades of climate change, development, drought and wildfires, the species is facing a rapidly increased the risk of extinction. State Department of Fish and Wildlife Commission will decide in June whether to accept the department’s recommendation to declare the tree an endangered.

As usual, there are two sides to the issue. Conservationists see this as a triumph of state environmental law while critics claim it as a misguided overreach because Joshua trees are already protected under many city and county ordinances and within the 800,000 acre national park.

Environmentalists argue existing state and local ordinances are largely inadequate at protecting species habitat loss, the endangered species listing will finally provide a statewide protection for the species, including requiring wildlife managers devise a recovery plant for the species, which could limit development in SoCal real estate.

The Joshua tree exists in high desert communities such as Yucca Valley or Hesperia, communities with lower average median household incomes. They are concerned the listing would impose additional burdens to real estate development, making it tougher to improve their property or curtail new development in their communities.

However, researchers warn time is running out. The tree’s range is contracting at lower elevations, its reproduction has come to a halt. Trees are failing to reproduce at lower, hotter elevations. They could become extinct in California by the end of the century!

This would be a terrible outcome for a truly incredible species. This remarkable species deserves protection. I believe this tree, in its own way is as majestic in its high desert setting as the coast redwood. These are species distinct to our California heritage. The Joshua tree deserves protection for our future generations to enjoy, marvel and be uplifted by this unique species.

Download a pdf of the article here: Los Angeles Times – eNewspaper

California Olive Trees Dying from Exotic Pest Infestation

Posted on April 10, 2020 by landscapeexpert

Olive tree displaying decline symptoms

With so many trees dying in natural and landscape settings, I’ve observed a disturbing trend throughout San Diego, and I assume most of the state. Property owners allowing dead and declining trees, palms and shrubs to remain in place. The problem with this practice, aside from aesthetics, is the dead plant may serve as a vector, whereby flying insects such as beetles, leaf hoppers, spittle bugs etc. may spread the disease to other uninfected trees.

Over the past decade, drought and climate change has taken a toll on millions of trees throughout California. Drought weakened trees succumb to secondary invaders such as wood boring bark beetles. There appears to be a continuous proliferation of new exotic pests resulting in diseases that are killing millions of trees in nature and within our urban forests and residential landscape settings.

Gold spotted oak borer

First collected and identified in 2004 was the gold spotted oak borer, (GSOB). This flathead borer is responsible for killing over 100,000 live and black oaks in San Diego County alone. There is no effective prevention or cure.

Reports of the disease known as citrus greening, previously confined to China, appeared in Florida, threatening the entire U.S. industry. The disease is a vector-transmitted pathogen by the

Citrus damaged by Asian citrus psyllid

Asian citrus psyllid. This disease ravaged Florida citrus growers. Once infected, there is no cure.

Another exotic pest first detected in Southern California in 2003 has been infesting hundreds of different species and is now established throughout the southland.

The Polyphagous shot hole borer is a small ambrosia beetle responsible for transmitting Fusarium disease to many tree species including avocado,

Sycamore bleeding from shot hole borer

box elder, coast live oak, maple, liquidambar, coral, sycamore and many other species. Fusarium is a vascular clogging disease for which there is no cure.

The list goes on and on. Climate change and an ever more connected world will continue the trend toward future invasive erotic pests.

In early 2000, olive trees, (Olea europea) became very popular as a landscape tree, heavily planted throughout southland landscapes. For the past decade, olive trees have been declining from a number of diseases. Two of the diseases are fatal, both display similar symptoms, making diagnosis difficult.

Foliage display tip and marginal burn symptoms

Symptoms appears as leaf marginal burning, tip dieback, leaf scorch, and loss of foliage color. Defoliation proceeds from the top down and outside in toward the trunk. Small twigs die back, eventually larger branches and entire limbs die. Depending on location and season, the decline may be rapid or slowly over the years.

Xylella or Verticillium?

Disease Infection

Diseases known as quick decline, leaf scorch, or variegated chlorosis are caused by Xylella fastidiosa, the bacteria best known for causing Pierce’s disease on grapes, but also attacks citrus, peach, almonds, oleander, olives and many other species.
Verticillium wilt affects olive trees in commercial and landscape plantings and many other species. The disease is caused by soil-borne fungi, Verticillium albo-atrim and dahliae.

Both are vascular clogging diseases, where the fungus or bacteria spreads throughout the vascular system, restricting water movement within the xylem tissue. However, they have separate means of transmission. Unfortunately, neither disease has a cure, infected trees and shrubs decline over time, usually resulting in death.

Description and Spread

Xylella is transmitted by the glassy-winged sharpshooter, (Homalodisca vitripennis), leaf hoppers and spittle bugs. These vectors are xylem feeding insects.
The pathogen multiplies and spreads throughout the host tissue, restricting water movement through the xylem tissue.
Insect vectors feeding on infected trees (such as olive and oleander) may acquire the bacterium and carry it to new hosts.

Verticillium is a soil-borne fungus, it invades the root system of olives when the soil temperature is cool.

After penetrating through roots, the fungus multiplies within the xylem tissue, interrupting and reducing water movement from the roots to the leaves.
Each disease clogs the vascular system, interrupting water movement from the roots to the leaves.
Both diseases have similar symptoms making identification difficult.

Common Symptoms: (not all symptoms may be present)

Xylella:

Tip burn
Leaf scorch beginning at the tip toward the stem (petiole).
Marginal browning, scorch and yellowing.
Twigs and branches dieback beginning in the upper crown.
Desiccated leaf and fruit drop.
Production of suckers.
Crown dieback

Oleander infected with Xylella

Verticillium:

Symptoms appear in spring.
Newer leaves curl inward.
Dead fruit clusters remain attached.
Loss of leaf color and luster.
Leaf and fruit drop follow.
Inward leaf curl

Progressive decline

Dead fruit retained

Individual branches and or large portions of the tree may die within one season.
The tree may not die, growth may develop on unaffected portions of the tree and suckering from the crown.
The new growth continues until re-infected; the cycle repeats the following year.
Vascular staining
Vascular staining may be present.

Control

There is no cure for Xylella or Verticillium. Recommendations for both diseases include:

Remove suspected plants immediately to prevent vectoring disease to other susceptible host plants, i.e.: olive, oleander, sweetgum, grapes, etc.
Integrated pest management to control insect vectors may help slow disease spread but spraying to control leafhoppers is expensive and futile.
Control of nearby weeds and grasses to help limit insect vectors.
Pruning out infected limbs may improve the appearance, but it is impossible to prune “below” the infected wood, so pruning does not get rid of the disease.
Fungicide applications are not effective.
Remove declining and dead trees immediately.
Replant with disease resistant species.

Avoiding the disease is most effective but not always possible. Soils are easily contaminated with Verticillium from former planting and the pathogen may survive in the soil for several years, ready to infect newly planted susceptible species.

While greenhouse soils may be heat pasteurized to kill the fungus, that is impossible in the landscape. Solarizing landscape soils has some effect at reducing verticillium infected soils. Prior to planting, rototill and irrigate the soil as deeply as possible. Cover the area with six mil plastic, seal the edges with soils to secure for six to eight weeks.

Effective cultural practices such as fertilizer application, irrigation management, weed and insect control may assist in preventing infection and possibly reduce the effects of the disease. Most of these practices focus on improving plant vigor that help mask the disease, however these treatments are not curative.

It is important to note, many of the foliar symptoms described above may also be due to drought or poor irrigation practices. There are also foliar diseases that may produce similar symptoms but are only minor and may not pose a serious threat.

Diagnostic laboratory testing is the definitive method for a positive identification of the disease.

The important take away is this: Don’t ignore decline symptoms in olive and other susceptible species, as the plant may be infected with a fatal vascular disease. Declining and dead trees left in place may serve as a source for the disease to be vectored by beetles, sharpshooters and other pests to healthy nearby trees. Remove dead or dying trees to prevent disease spread.