Today a customer asked me this question, “We will want the trimming done, but don’t have a date yet. It depends on the progress with the construction. What are the ideal dates for trimming?”
What are the ideal dates for trimming?”
February 2, 2010
Ideal Time to Prune Trees & the Oak Wilt Pruning Season
September 14, 2009
Planting New Trees In Oak Wilt Sensitive Areas
Oak wilt is a serious problem in central Texas. It kills neighborhoods worth of trees at a time. Implementing control programs is crucial, but implementing programs to plant replacement trees is arguably more important. But, what kind of trees should be planted?
Lately, the popular choices have been wilt resistant oak species: bur oaks, chinquapin (cheenk-a-pen) oaks, monterrey oaks and lacey oaks. While these are all reputable trees, they are not without their own limitations. Bur and chinquapin oaks in their natural setting are found in river bottom areas where there is substantial water available in the underground tables. Planting these trees in the hill country or on a rocky slope is not a good idea without irrigation; even then, you are testing mother nature’s boundaries. Monterrey and lacey oaks are better adapted to rocky slopes and dry conditions, but you should know that these are not tall growing trees. Monterreys get a little taller than the laceys, but both max out around 15-20 feet. And, their life span is relatively short as well. Depending on planting conditions, you should expect 20-40 years. Maybe that’s long enough for you, but come on, you are going through all the trouble to plant a tree; why not plant something that will grace the neighborhood long after you move on.
My favorite trees to plant are the natives, even the ones people shun because of oak wilt susceptibility. Live oaks and red oaks are two of the best adapted varieties of trees for the central Texas area, but many people write them off because of oak wilt. The reality is that transplanted oaks generally don’t graft roots with the natives and will survive an oak wilt onslaught. Cedar elms are another good choice for central Texas, and these trees are hardy to a large variety of growing conditions.
Live oaks and red oaks are the best trees for the area. It’s bad enough that oak wilt is killing them. We don’t the to make the problem worse by failing to replant these spectacular species. Basing your planting selection on one single tree disease is succumbing to evil’s trickery. Just because a tree is tolerant of oak wilt, doesn’t mean it won’t have other problems. And, oak wilt control is getting better all the time. With the digital age upon us, documentation and our knowledge base is improving. Mark my words, one day soon, we will be able to effectively treat and control oak wilt. Help restore our oak forests by planting new live oaks and red oaks today.
May 7, 2009
Identifying Oak Wilt: the Challenges and the Solution
A lot of what I have to say here is aimed at the challenges of diagnosing oak wilt. But, be patient, at the end I’ll tell you the best way to get the answer you need. According to research, diagnosis is the main factor that causes problems with management plans (Appel 1994). Let me tell you, my experiences out in the field completely back up this research. It may seem obvious to you that diagnosis is important, and why would that be causing such a big problem with oak wilt strategies? There are a few interesting points on this subject I’d like to spell out for you.
The same symptoms of oak wilt are caused by many other tree disorders. To understand this you need to realize that the words “symptom” and “diagnosis” don’t mean the same thing. I could write a whole article on the relationship of symptom and diagnosis, but we’re talking about oak wilt here. As an example, if you look at the Texas Forest Service oak wilt site (http://texasoakwilt.org) you will see that one symptom of oak wilt is vein banding. Here is a short list of other tree disorders that also display vein banding: chlorosis, herbicide damage, root damage, transplant shock. There are more. If you do go to the website I mentioned before you’ll see that there are several other leaf symptoms that you might find on an oak wilt site. All of these other symptoms can also be caused by many things other than oak wilt.
Our understanding of this disease is in its infancy. Up until the 80’s we didn’t even realize that oak wilt was the disease killing our native treasures (thank you Lewis & Oliveria 1979). We were aware of oak wilt before then, but didn’t know it was responsible for so many of our problems. It wasn’t until 1994 that a proper management plan was developed by a qualified pathologist (Appel 1994).
“A five step diagnostic protocol is recommended for routine tree diagnostics in central Texas. Although designed to distinguish oak wilt from other diseases, the protocol has proven useful in diagnosing any tree problem. The completion of all five steps is unnecessary to make an accurate diagnosis and may be impossible. The five steps are: 1) observe the pattern of dieback and mortality in time and space for the tree population, 2) observe the patterns of dieback and mortality in time and space for individual tree crowns, 3) examine specific organs, e.g. leaves, branches, or roots, for unique patterns of chlorosis and/or necrosis (symptoms), 4) examine specific organs for evidence of the pathogen (signs), and 5) attempt to obtain laboratory isolation of suspected pathogens.”
There is one part of this excerpt I would like to draw special attention to, “observe the pattern of dieback…in time and space.” In my experience this is the most overlooked part of the diagnostic process. Any potential oak wilt site needs to be monitored over a period of time. I’m not talking about a week or a month. A good arborist, who is capable of diagnosing all tree disorders not just oak wilt, needs to visit the site about 4 times over the course of a year. I can’t tell you how many times I show up to meet with a potential client and they have already been told they have oak wilt by 3 different people who have just seen the site for the first time. I think this is unreasonable and irresponsible, and is an obvious breech of the recommended protocol.
Ideally photographic evidence should be taken. A picture is worth a thousand words. It’s easy to get into a conundrum over what the tree really looked like a year ago when you are trying to go by memory. In today’s digital photography world, it is so easy to do there is no reason not to.
April 17, 2009
Is my tree sick?
This may seem like a simple question, but it is not. Here’s the “X” factor that makes it hard to know if your tree is sick: trees have energy reserves. This means that when something afflicts your tree, the tree is going to fight a good battle without you ever knowing it. But, there are some subtle signs to look for. Here are the secrets you need to know.
Let’s start with the leaves; that’s the only thing most people take notice of anyway. The first thing to look for is color. Ninety nine percent of tree species are supposed to have a very dark, rich-green colored leaf. If the leaves aren’t green, they’re usually some shade of yellow-green or brown. Obviously brown is bad, this is serious. However, yellow is serious, too (often the precursor to brown). The “yellowing leaves” condition is generally refered to as chlorosis (klor-osis), which can be caused by many things. The next leaf characteristic to look for is leaf size. One of the first symptoms of many tree disorders / stresses is for the tree to shrink leaf size. This symptom can be trick for non-arborists. Healthy leave size varies from species to species and even from location to location. For example, a live oak located near lake Austin should have leaves about 2” long, whereas, live oaks in the rocky slopes of the hill country should have leaves about 1 ¼” long. The last leaf characteristic to look for is leaf shape. Again, this one can be tricky for non-arborist because you’ll need to know what the leaves are supposed to look like.
The other place to look, besides the leaves, is at the ground. Very often trees main problems are that we have damaged their roots or rooting environment. Cutting roots, compacting soil and filling soil around tree trunks are the most common injuries. Most of the time these activites are related to some sort of construction activity. I doesn’t take much; 75% of tree roots are in the top 12 inches of soil, and they do extend all the way to the surface.
Determining if your tree is sick or stressed is just phase one. You’ll then need to make a proper diagnosis so that a comprehensive treatment program can be implemented. It’s always a good idead to hire an arborist if you really have a sick tree. Reading about something isn’t replacement for field experience. If you can’t afford to hire a tree guy for their service to provide treatments, caughing up $150 for a consulting fee will save you great amounts of time, money and frustration in the long run.
I'm Keith Brown, owner of Austin Tree Experts. This is my repository of tree knowledge. I hope you find what you are looking for. Let me know if you don't.
