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Section Date Posted
Fall 2003 (PDF)
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Fall 2002 (PDF)
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Message From The President
Bioinvasion: A Great Threat (11-03)
Ancient Trees- Our Link with the Past (12-02)
Old Arboriculture (09-02)
Professional Accuracy (09-02)
Spring Observations (09-02)

Bioinvasion: A Great Threat
By Jerry Pulley
Tree Clinic Quarterly, Fall 2002

About 240 million years ago, the Earth's landmasses combined into a single continent. That immense plaque of rock we refer to as Pangea sat amidst an even more immense global ocean. With steady geologic pace the rockmass fragmented and sailed throughout those immense waters to create our present continental map.

From the perspective of the human moment it seems the structure of our planet is surely one aspect of the world that humans cannot change. Evidence however suggests otherwise.
With ever increasing speed the world's economy is pushing its many ecosystems into each other. The currents of human movement are altering the ancient evolutionary function of the global surface.

Historically, the structural variety and the uneven surface of the earth have held living communities in place. The barriers surrounding an ecosystem set the terms of life within it. They tied a group of plants and animals together and tended to exclude predators, competitors and diseases that evolved elsewhere. Perhaps the most well known example is the island of Galapagos where creatures like the giant tortoise evolved into forms known nowhere else on earth. Today, the heretofore physical barriers are losing their ecological reality as more and more organisms are moved around them.

Until recently the arrival of new organisms, or "exotic species", was a rare event. Now it happens any time an airplane lands or a ship ports. Exotics are arriving thousands of times faster than the previous natural rate. These non-native species, when introduced to a new area, can out-compete native species, cause disease to, and ultimately wipe out native species. In any single ecosystem, loss of species represents decline.

Under natural conditions the planet's physical structure (oceans, deserts, mountain ranges, etc) imposes formidable barriers to cross. Now those crossings are routine. Every few months we hear of a "new" pest. One example is the Asian Longhorned Beetle that arrived in
shipping crates at major U.S. ports only a few years ago. It is killing thousands of maple trees in the New York and Chicago areas. It has been found in Houston. The Emerald Ash Borer, a native to Asia also arriving via shipping crates was discovered in Detroit earlier this summer after the recent large-scale rapid decline and death of ash trees. Citrus Longhorned Beetle, a relative of the Asian Longhorned Beetle was recently found in a nursery in the Pacific Northwest. It reproduces in the vegetation along river systems and has the opportunity to impact thousands of trees, miles of wetlands, wildlife, salmon habitat, fruit orchards and ancillary services througout the Northwest. It has no known natural predator in the United States to keep it's population numbers in check.

Invasive plants with no natural controls are troublesome throughout the world from Hydrilla in our own Lake Austin to Kudzu in the southern U.S. Water Hyacinth in Africa's Lake Victoria comes from South America. Melaleuca, an Australian native, is choking out native species in the Florida Everglades.

The list of invasive exotic species seems endless. Exotic agents of disease are more numerous than insect pests. Dutch Elm Disease, Chestnut Blight, Oak Wilt, Sudden Oak Death (see page 4), Hoof and Mouth Disease- all are caused by non-native invasive organisms.

The effective collapse of the world's ecological barriers is a phenomenon without precedent in the entire history of life, certainly human life. Bioinvasion, the spread of exotics, is fast becoming one of, or, perhaps the greatest threat to the Earth's biological diversity. It seems to me that we are experiencing evolution in reverse.


Ancient Trees- Our Link with the Past
By Jerry Pulley
Tree Clinic Quarterly, July 2002

I’m a history buff of sorts-especially Texas history. My mom’s maternal antecedents were veterans of the battle of San Jacinto, the decisive event in Texas independence from Mexico in 1836. I try not to bore folks with tedium but for anyone interested I am happy to give you a story.

Last March I took a friend on a historical tour. First, we drove to old Fort Clark Springs, west of San Antonio. Fort Clark, established in 1852, is the best preserved of all of the Texas frontier forts. In 1852, it marked the western edge of civilization. Beyond was the Comanceria- Indian territory so well immortalized in the novels of Larry McMurtry, Elmer Kelton and other Texas writers. The fort was commissioned to protect the settlers from marauding Indians: Mescalero, Lipan, Kiowa, and the war-painted horsemen of the plains, the fierce Comanche.

The fort’s original buildings, largely unchanged, surround the huge parade grounds. The enlisted mens’ quarters, officers’ mess, and the livery stables are all there. It’s easy to imagine Buffalo soldiers of the 9th and 10th cavalry milling about.

The fort is located just up the hill from the headwaters of Las Moras Springs (the Mulberries). Originally the springs consisted of a strip 1-2 miles wide and extended downstream for several miles. In approaching the source of the spring, we drove through a modern park with an asphalt drive, grass neatly mowed, picnic and litter barrels nicely painted and signs admonishing us not to litter. We found the source- spring water bubbling up from the ground and contained by a concrete wall looking something like the Army Corps of Engineers might have dreamed up. Down stream a couple hundred yards was a dam creating a concrete pond, or swimming pool.

My friend commented, “What a shame. What do you think this originally looked like?”

“It’s not all gone” I replied, “The trees are still here.”

Grand, majestic live oaks stand just as they did under Spanish rule, 300 years ago. These were mature trees when the Alamo fell. They have grown very little if any, in the 166 years since. All exist in a deteriorating condition resulting from old age exacerbated by abuse and neglect from their human keepers. Still, they are the living witnesses to antiquity and they are there for us to appreciate. (continued on next page) Few if any of these old soldiers will be there for my grandchildren to see. The following generations will have to be content with plaques and historical markers to describe the first 200 years of Texas history.

Old trees like old people are our living connection with the past. Go see them both, and discover something about yourself; discover something about our history. It’s better than reading about it.

Remember though- time is short.


Letter from the President: Old Arboriculture
By Jerry Pulley
Tree Clinic Quarterly,1st Qtr. 2002

Last month I said, "OK, it's time to formalize a mission statement for Tree Clinic." As with many groups, we individually have a notion of our mission, but we had not distilled the concept to a declarative statement. We agreed that our mission is:

To serve clients by solving plant health problems through the application of scientific principles and procedures.

A few days later, I was introduced to a fellow who, upon hearing my name, said, "Oh, you're the tree surgeon!" He meant no insult- it stung nonetheless. I replied, "No, I'm an arborist- a tree biologist, actually."

My new acquaintance who used the term tree surgeon was thinking what is called OLD ARBORICULTURE. It was based on three elements: Cut the branches close to the stem, paint the wound, and fill the cavity with concrete. Old arboriculture is still practiced today to some extent. Why? Ignorance, of course. People want to dress wounds, cut out decay down to clear wood, and fill holes to prevent rot. In effect, they want to… "treat trees like they treat animals" (Shigo, Alex. Modern Arboriculture, 1991, pg.18). Trying to change public perceptions of these treatments has not been easy, even with all of the scientific evidence showing that many of the old treatments do more harm than good. Old perceptions are indeed very old:

"At the beginning of recorded history, the Greek and Hebrew writings reference crop maladies like rusts, mildews and smuts that were assumed to result from the wrath of gods.

The philosophers Pliny and Theophrastus observed, and speculated on the nature of diseases. It is interesting to note that Theophrastus (300 BC) recognized that wild trees were not liable to the ravages of disease, as were those that were cultivated.

Linnaeus, the botanist responsible for our binomial system of scientific classification published Species Plantarum in 1753. His contemporaries attempted to classify diseases simply for the sake of classification. During that time occult influences that presumed diseases to be the wrath of angry gods still persisted although there was some awareness of the role of the environment. It was during this period the first pruning wound dressing was developed for fruit trees. This appears to be the origin of the idea that wound dressings do something for trees. This occult- fostered idea persists to this day. It was not until another hundred years had passed that the chemist Anton deBary demonstrated the causal nature of fungi in cereal diseases and later identified the fungal causes of potato blight that decimated the Irish population in the great potato famine. In the evolution of plant science we see a series of transitions from philosophical and occult interpretation to descriptive arid taxonomic classification to the application of scientific investigation."

There is a wealth of information on diagnoses and management of plant maladies available today to those interested.

We at Tree Clinic will strive to solve your plant health problems through the application of scientific principles and procedures.


Letter from the President: Professional Accuracy
By Jerry Pulley
Tree Clinic Quarterly, 4th Qtr. 2001

The media are preoccupied with terrorism, with good reason, of course; it's certainly an urgent issue. Often though, in the reporting of urgent issues, information becomes distorted. Pertinent information may be poorly explained or omitted entirely. Distilled information easily becomes misinformation. With something as threatening as the concept of terrorism, or more specifically, biological terrorism in the form of anthrax, misinformation promotes fear.

The other day, in a radio report, I heard an officer of the CDC (Center for Disease Control) refer to anthrax as a virus. Perhaps he simply misspoke, and promptly corrected himself. If so, the correction was not reported. That error constituted misinformation, because it is important to know that anthrax is a bacterium (Bacillus anthracis), not a virus. Bacterial infections are treatable with antibiotics, viral infections are not.

Scientists and reporters alike must be careful to speak accurately. As an arborist and diagnostician, I must be careful not to advocate for a tree or its disease. If I can relate the facts in full, my client can make an informed rational decision about a course of action to take.

One common tree disease I see every spring and fall is requiring greater detail in explanation these days due to its name. The tree disease anthracnose is caused by a fungus. Fungi are entirely different from viruses or bacteria. The name, which sounds very similar to the bacteria disease anthrax, may cause alarm to clients in these troubled days. Even though the names are similar, they are not similar diseases. The word root anthrac- is derived from the Greek word meaning coal, or charcoal (the lesion caused by the cutaneous form of anthrax is black, or charcoal in appearance). Add the prefix anthrac- to a suffix -nose, which means condition or disease, and you have the word anthracnose, meaning "black disease", which describes a plant disease caused by a fungus and recognized by black, dot sized fruiting bodies on dead lesions in the leaf. This disease is not lethal, and is treatable with fungicides.

In the words of Jacob Bronowski, "Man masters nature not by force but by understanding". One way that fear and panic can be avoided is for all of us who speak to the public to take care to speak accurately.


Letter from the President: Spring Observations
By Jerry Pulley
Tree Clinic Quarterly, 2nd Qtr, 2001

Spring is here, and the phone is buzzing. Lately I've been spending many a weekday afternoon on the phone with clients who have concerns about their trees. Reflecting on the many calls of late, it seems to me that spring is the season when people observe the most detail about trees. As the year progresses, detail in observations evidently fades. A late season housecall in August may reveal a major limb broken or even an entire tree that has turned brown. The homeowner is often surprised, and will remark; "I hadn't noticed that!"

Spring is different. After several months of cold and rain, we are anxious to be out of doors, into the sun, and are delighted with signs of new growth and new life. It seems that even the slightest detail of seasonal development is observed. This usually helps when you and I are trying to get to the bottom of a sick tree problem on the telephone. For example, when you describe the detail of how a developing leaf appears eaten away, it is easy for me to explain the life cycle of the Snoran Tent Caterpillar, and the effect on your tree.

We humans suffer runny noses, colds, and flu during winter months. Trees also suffer ubiquitous diseases, but show symptoms in spring, when the environment is conducive to growth and reproduction. Signs and symptoms of insect damage, foliar fungal infections and nutritional deficiencies seem to show up overnight. Most are not life threatening if addressed on a timely basis, but as with human illness, they must be addressed to maintain optimal health of the whole organism.

Unfortunately, some tree diseases are life threatening. Oak Wilt is unquestionably the worst that we deal with. This complicated disease is difficult to discuss in a concrete matter-of-fact way. It can be discussed only in the abstract. Almost any statement one can make about the disease has exceptions, sometimes apparent contradictions. Despite the best attempts at treatment, we often lose trees to Oak Wilt. There are no guarantees, just as in treating some diseases of man. Step one, for me, in helping a client address oak wilt is to initiate a conversation that educates about what is known and perhaps more importantly, what we don't know about this devastating tree disease.

So, go outside- take a look around. Observe your trees, and if you see anything that concerns you, give me a call.


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