Live Oaks are semi-evergreen; so, why am I writing about fall color on a live oak? Sometimes live oaks will produce fall color. But, usually not in the fall. When it happens it’s in the winter. I was somewhere between Hamilton Pool and Johnson City driving between jobs when I ran across these shining examples.
It’s funny to me what gets “diagnosed” as lightning strikes. It seems to me the average homeowner thinks the only two afflictions known to trees are oak wilt and lightning. Hopefully, this simple post 
will shed some light for many of you wanting to know if your tree was struck by lightning, and if so, what you should do about it.
The main thing you need to look for is a narrow wound that stretches the length of the trunk from the upper canopy to the ground. Typically, lightning doesn’t strike the tree half way down the trunk. It hits somewhere out near the tip of the canopy. Then, the charge travels down the trunk of the tree into the ground. In this picture, the strike barely blew-off the outer layer of bark. (more…)
Soil restructuring is one of the most powerful tools we have for tree health management. The idea is to till the soil; improving its structure will allow valuable air and water to more easily penetrate the soil. While fundamental in gardening theory, this task is not easy at the scale of a large tree.
One of the first challenges we must deal with is maintaining tree roots while tilling the soil. After all, we are trying to help the trees here! This challenge is overcome by use of a tool called an airspade. An airspade is an over powered air compressor that blows away dirt without damaging the tree roots. There is just enough power to displace soil, but not enough to cut through roots.
In most scenarios, we will till the top 4-8” of soil depending on the site conditions. We’ll then add about 2” of finely ground mulch or other organic matter and then re-till the soil to get it all mixed up good. Once this part of the process is completed we’ll top dress it with about 4” of mulch.
The end product is an inviting soil that is great for growing anything. This is as close to mimicking a natural forest floor as we can get in an urban environment. Add a few small to mid size shrubs to provide an additional layer of shade to the soil surface and some irrigation and you’ll have a full blown tree utopia!
Fertilizing your tree will provide a big impact to the health of your tree in both the short term and long term. More than pruning, more than any other tree care service. There is a lot to know about tree fertilizers. This article is meant to be an introduction to tree fertilizer. I highly recommend you read my three other articles in this series: When to Fertilize trees, How to Apply Fertilizers to Trees, and What Products to Use for Fertilizing Trees.
You can compare tree fertilization to your own health care. Without it, you are not going to wither and die tomorrow. But, with proper health care (fertilization regimen) your tree will have a healthier, more full canopy of foliage. And, if a good fertilization regimen is followed for a few consecutive years, sick trees can return to a healthy state and regain extended life expectancy.
One of the biggest misconceptions I find people to have is a perception that tree fertilization mostly make a tree grow faster. I can see where someone would come to this conclusion. Most of us get our experience in fertilizers from grass fertilizing. Grass fertilizers do result in faster growing grass. Trees are different that grass. Grass is in a constant state of growth and trees only grow a few times a year; we call these growth increments flushes. The ultimate goal with trees is to time the right treatments so that roots are stimulated to grow faster, but foliage is stimulated to develop better (not grow faster).
Timing is critical. Here are the basics you need to know about timing: most root growth takes place in the fall; most foliage growth takes place in early spring; there is not much growth in the middle of the “growing season.” With this knowledge you should be able to deduct that fertilizing in the summer would be a waste of time. During the spring you should use unconventional treatments to stimulate healthy development not conventional fertilizers that would stimulate growth. Your conventional fertilizer should be applied in the fall when roots are doing most of their growing.
Here are some common comments I hear about tree fertilizing:
Q: These trees were growing here long before I was here. They didn’t need fertilizer before, why now?
A: Ok, true. But, before you were here there was a natural balance of nutrient recycling. Now, the soil’s litter layer is gone and replace with grass.
Q: Fertilizing is just going to make it grow faster, then I’ll have to prune it more.
A: We just discussed that a good fertilizer regimen doesn’t stimulate growth. Quite the opposite, healthier trees will produce fewer dead limbs over time, therefore, reducing pruning needs.
Q: I don’t like putting chemicals in my yard.
A: You shouldn’t. But, what are you considering as chemical? Fertilizers are less harsh that virtually any cleaning supply you use and you actually get that stuff all over your hands and up your nose. And, if you get your timing right you can reduce your application rate dramatically. We target about ¼ lb nitrogen per medium sized tree per year. That’s 12 times less that what is recommended for 1000 sq. ft. of lawn. Every other product we use is not chemical at all (see my article on what products to use for trees).
One last topic I want to discuss before leaving is soil restructuring. Many of the trees in our urban environment get left with small little islands of soil to grow from. There is a tool called an air-spade we use to air-till the soil and mix organic matter in. Tilling with this over-powered air compressor allows us to till the soil without destroying all the tree roots. This treatment is a huge improvement to the soil structure and is great for all trees, especially those in limited rooting environments.
Summer heat stress is one of the number one tree killers I run into. Okay, realistically no tree ever dies from just one problem, but rather a cumulative affect of many stress factors. Heat and drought stress are stress factor that almost all trees in the central Texas area deal with on an annual basis. So, if your tree has some other factor stressing it out, the summer heat might be the straw that breaks the camel’s back. I see more trees die during the summer time than any other time of the year.
Crepe Myrtle with droopy leaves
Some trees suffer from heat stress more than others. For example, live oaks and cedar elms cope very well; sycamores and cottonwoods with will begin shedding leaves with moderate heat levels if water is scarce.
One important factor to consider when trying to quantify damage from heat stress is to take note of the date when your tree loses all its leaves. My experience has been that if a tree can hold its foliage through July into August then it will usually leaf out full the following spring. In some cases the tree will even put on a new set of foliage in September to effectively produce more sugars for itself through the fall growing season. Worst case scenario is if your tree succumbs to a heat wave in the spring. We’ll often get a hot spell in April or May that will reach 100F. If your tree loses all its leaves this early it probably won’t bounce back.
I get asked this question very often. Ball moss is something that we’ve all seen and are all familiar with, but there are still plenty of questions surrounding it and what it does.
To answer the age old question, you need to understand what ball moss is and what it isn’t. It is not a parasitic plant that is pulling nutrients out of your tree. It is in the Bromeliad family (so are pineapples). Ball moss is actually an epiphyte, similar to many mosses, lichens, algae and even ferns. It can grow pretty much anywhere…trees, power lines, on a wall, gutter or even that old car that has been sitting in your driveway for a couple of years now. Epihpytes derive their nutrition from the air and only need physical support from their host. Ball moss spreads by tiny seeds, which are carried through the air by wind, rain, squirrels and birds, which makes it near impossible to completely stop the spread of it.
Ball moss has been know to cause some minor physical damage to its host (trees). If allowed to grow unchecked for a long period of time, ball moss can grow so thick that it inhibits leaf production. Basically ball moss blocks leaves from forming, so the tree then has a limited amount of foliage that it is relying on, which in turn means less food for the tree. Aside from that, ball moss causes no damage or harm to your tree, other than it being unsightly.
The best course of action with ball moss is to have it taken out of the tree when you have your regular maintenance pruning done. This should typically be done every couple of years, just depending on what species of tree you have. By simply removing dead limbs in the tree, you’ll get quite a bit of the ball moss out (usually 60-70%). If that isn’t enough for you, then talk to your arborist and let him/her know that you’d like as much of it taken out as possible. Just keep in mind that ball moss is not killing your tree and in 90% of cases, there is no action needed aside from regular maintenance.
Herbicide damage is one of the biggest tree killers I run into. Weed-n-feed products are the number one culprits. If you buy a bag of fertilizer from your local do-it-yourself store make sure that the bag does not have weed control mixed in with the fertilizer. Most weed control products will affect boad leaf plants and go unnoticed to grasses. Trees are in the broad leaf plant category.
The most common chemical used in these weed-n-feed products is atrazine. This chemical shuts down the sugar making process of any susceptible plant that absorbs the product. For a small weed that has a very short life cycle this shut down of photosynthesis results in death within a few weeks. Large, healthy trees can tolerate the chemical. The sugar making process will be shut down temporarily, but once the product is flushed from the system and leached from the soil the trees normal processes will return. This usually takes a couple months from the time of application.
There are a couple of factor of the herbicide application that will affect the severity of damage to the tree. Timing is a big deal. Applying the weed-n-feed while the tree is growing its new leaves early in the spring is the worst time. This will always result in deformed and burned foliage. Ruining a trees new foliage in the beginning of the year leaves it with a crippled canopy for the entire growing season. However, if you apply the weed-n-feed during the summer when there is no growth taking place and the trees photosynthesis is shut down due to heat and lack of water the chemical effects might have very little detriment to the tree.
The next big thing is frequency of application. Any healthy tree will usually tolerate one application of herbicide with little or no visual signs of stress. Two applications in a single season will normally cause a canopy to begin thinning. Treating once a year for three or more consecutive years can kill the tree.
It is possible to control weeds in your lawn without killing your trees. Hand pulling the weeds is the best if you have few weeds. If you have to use chemical then spot treat with Round Up or similar product and do not broadcast weed killers over the entire lawn. Or, hire a pro to do it. These days you can usually hire a professional lawn care company to do your lawn fertilization and weed control for the same price range you would pay to buy the products yourself.
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.
Let’s face it. Tree health care isn’t on the same level as your primary care physician. Skipping past the fact that it would be unreasonable to expect technology to be on a similar level, the real issue is that trees’ best interests are usually not the primary consideration in the planning in our shared urban environment. Even still there are some fundamental ideas we can work with to improve any tree’s chances for survival. Proper pruning, applying timely treatments, improving soil environments and regimented monitoring are all tools that arborists have to help fight the fight for our green friends.
Let’s start with pruning. This is the first thing most people think of when they think about helping their trees. As an experienced veteran tree guy, I can tell you that most people get the wrong idea about pruning. With native trees in Austin, like the live oak, pruning is usually done for functional reasons rather than for the tree health. The right idea is to prune the tree in a manner that we can live with it without damaging the tree. Cleaning out deadwood will definitely improve the trees longevity, but cutting off limbs so we can drive under them is not ideal for the tree. Ideal would be moving the road. You can learn more about tree pruning by reading my pruning series here. In general, tree pruning is the least impact factor for improving health for sick trees.
The highest impact approach for seeing quick results is implementing a series of timely treatments. Understand, when I say quick results I mean 1-2 years. There are very few scenarios where we can produce visually noticable improvements for tree disorders in less than a year. Lets look closesly at my statement of “implementing a series of timely treatments.” The most common mistake I see made when attempting to fertilize a tree is that people (even many arborists!?) will pump a bunch of nitrogen in the ground at no specific time of the year and then walk away from the tree as if all its problems are solved. The important thing to know here is that timing is CRITICAL. I like to explain this by comparing trees to grass. Grass maintains a constant state of growth; that’s why it has to be cut once a week. You can put fertilizer on turf at any time and get virtually the same response: greener grass and faster growth. Trees are not the same. Trees go through a cycle of defferent growth stages through out the course of the year. Early in the spring the focus is on foliage growth; virtually all trees are producing an entire canopy of leaves. During the bulk of the “growing season” there is very little growth (percentage wise); this is mostly an energy producing time for trees. As late summer and fall approach the trees’ focus shifts to root growth. Sixty to seventy percent of a tree’s root growth for the year takes place in the fall. So, depending on what time of year it is, the treatment is going to have a different affect on the tree. It is mission critical that you put the right stuff on the tree at the right time of year.
Improving the soil environment is a relatively new technique being used by arborists here in Austin, and a very good one. What I’m talking about here is basically air-tilling the soil and mixing in organic matter. Our native “soils” are heavy clays with very little, if any, organic matter. Mixing in organic matter improves water penetration, aeration and microbe activity among other benefits. The new development that is making this popular is the use of an airspade. In the past there was no good way to till up the soil without destroying the inhabiting roots. An airspade is a high powered air compressor tool that blows apart the clay chunks. This breaks up the soil and doesn’t damage vital tree roots. Although not necessary in every situation, this is an important technique in our arsenal of tools.
Every sick tree is going to be a different scenario. There is not a template you can apply to every tree. The foundation for any successful recovery is diligant monitoring and keeping good notes. My company policy is to keep a map showing the location of every tree on a property and taking a photo(s) and notes on every inspection; 4 times per year as a minimum. The trees condition will be constantly changing.
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.
