2009 August | Austin Tree Experts Blog

August 24, 2009

Part 3. How to Apply Treatments to Trees

There are a variety of ways to apply tree fertilizers and other treatments. For the average layperson, applications to a tree can be challenging. High pressure sprayers are readily available at equipment rental stores, so you can do it yourself, but this equipment is not easy to use. Accessing a tree’s root system deep in the soil or reaching the upper boundaries of canopy on a mature tree requires this special equipment.

Deep root injections are the most common application techniques for tree fertilizing. A pressurized water pump system is used with a “deep-root needle” attached to the end. This needle is inserted into the soil to the desired depth; usually 6-18” deep depending on the site’s soil. The treatments are applied every 2-3′ in a grid pattern throughout the drip-line of the tree. This technique provides a few important benefits. Applications made deep into the soil bypass turf and other small landscape plants root system so competition is reduced. Also, the root needle is about 1” in diameter so everywhere it is inserted a hole is left behind. Soil aeration is an indirect benefit from this application technique.

The next most common application technique for tree treatments is a canopy spray. There are several scenarios when product needs to be applied directly to the foliage. Such as treatment for many foliar fungal diseases, or when we apply our growth hormone treatment to foliage in the spring. Special care must be taken with this application technique. You must make sure the product is not going to be harmful to adjacent plants and the treatment technique should not be done on windy days.

Two techniques for trees that are good for providing direct access to trees systems while maintaining minimal environmental exposure are injections and basal drenches. A trunk injection works much like an I.V. works on you when you go to the hospital. Holes are drilled directly into the tree and a pressurized system delivers the treatment straight into the xylem of the vascular system. Basal drench is just as it sounds. A small concentrated product is poured around the base of the tree and is slow release delivered to the tree over time. By digging a moat before application and covering over when finished, there is very minimal chance of any person or animal being exposed to the treatment.

My hope is that future tree fertilizers and treatments will applied by trunk spray. There is a product out there called Pentra-Bark. Mixed with a treatment products , Pentra-Bark forces the product to absorb through the bark and into the tree’s vascular system. This treatment technique is non destructive to the tree (unlike trunk injections) and provides direct access to the trees system. Using the trees own vascular system to distribute product is very smart. Currently there are no treatments labeled for use with trunk spray technique here in central Texas, but my hope is that this well begin to change soon.

Filed under: Fertilize — Keith @ 7:40 am

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August 20, 2009

Tree Selection. How to Pick a Tree.

There are two basic categories you need to address when it comes to tree selection. What is the best tree for your planting site and how to pick a quality specimen. You need to get these two things right or all you labor will be for nothing.

bud scale scar

Lets start with selection of a quality tree. Let’s start by looking at the leaves. The deeper green the color the better the leaf. Unfortunately, this technique is only completely reliable in the spring. If you are looking in the summer or fall this will be deceiving because the trees may be going through normal leaf drop or heat stress. You shouldn’t plant in the summer anyway, so you shouldn’t be looking then. If you are trying to find a tree in the fall, look at the bud scale scar. More distance between these scars indicates more growth, which can be an indication of healthier trees (or better fertilizer). This only works when you are comparing trees of the same species.

The next thing to look for are trunk wounds. Don’t buy anything with injuries on the trunk.

The tree on the left will have good structural growth. The tree on the right is more likely to have breaking limbs in the future.

Growth form is another important factor if you are looking for a large growing shade tree. You want a tree with a single trunk all the way to the top. Think Christmas tree. Often, there will be a biforcation (joint) in the lower part of the tree and you will have a “double leader.” This is basically two main trunks. These trees will have structural integrity problems in the future.

Picking the right kind of tree for the right place can be tricky. For this part I highly recommend consulting with your arborist. You need to be careful taking advice from the nursery. They don’t know where you live or what your site looks like. There are a few important topics to discuss with your arborist.

Do you want a small ornamental tree or a large shade tree or something inbetween?
Is the tree going to be pampered or thrown to the wolves? (auto-irrigation, fertilized regularly)
What other landscape changes do you want to make around the tree’s planting site?

Follow these steps and you should wind up with the right kind of tree and a nice looking specimen.

Filed under: Tree Planting — Keith @ 6:41 pm

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How to Plant a Tree

Planting a tree is slightly more complicated than digging a hole and sticking a tree in it. But, not too much more complicated. Follow these few tips and your new tree will be sheltering you from the sun in no time. And, by that, I mean in a few years.

The first step is to pick a tree, but that is another blog. Once you have the right tree it’s time to find the right place to plant it. The rookie mistake here is to look around at the ground to find your spot. LOOK UP! You want to find a place where adjacent trees’ canopies won’t be crowding your new tree too much. You want an open view of the sky from your planting spot.

Now it’s time to start digging. The depth of your planting hole should be the exactly the same as the root ball of your new tree. If you hit bedrock and can’t go deep enough, this is okay. However, if you plant the tree too deep it will be certain death. When you can’t dig deep enough, just mound the soil around the root ball and add a little more mulch than you normally would to help insulate. Do not chip a hole in the rock to plant. This hole in the rock will not drain water and will become a cesspool of root disease. For width, make the hole about 12” wider on all sides than the root ball so you have room to add fill soil around the root ball.

Before you put the tree in it’s new home you need to prepare the root ball. Most people have a hard time with this. Normal instinct is to be very cautious with the precious roots, but what you really need to do is tear them up. Trees sitting in a container at the tree farm end up with roots growing in circles around the edge of the container. We need to loosen or cut these roots or we’ll end up with girdling roots in 10 years and you’ll be wondering why your tree randomly died.

Now it’s time to stick your tree in the hole. But, first double check to make sure that your root ball and hole depth are still the same. Tearing up the root ball may have changed this. Throw some dirt in the hole if needed to bring the top of the root ball to surface level. Now that your tree is in the hole, throw some dirt around the edges to fill the hole. I like to mix some of the native clay with some sand, topsoil, and mulch, but you can get away with just using the dirt you pulled from the hole or topsoil from the local garden store or nursery. Top with 3-4” of mulch and you are good to go.

Water the tree thoroughly before putting the mulch down and water it every three days for the first 6 months.

Filed under: Tree Planting — Keith @ 5:17 pm

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August 17, 2009

Tree Fertilizer, Part 2: When to Fertilize Trees

Timing might be the most important factor to successful tree fertilizer applications. Even if you use quality products you can injure a tree by providing the wrong fertilizer at the wrong time of year. I like to describe tree fertilizing by comparing to grass fertilization practices. You can fertilize grass virtually any time of the year with a variety of products and get the same results: greener grass and faster growth. This is because grass is in a constant state of growth (evident by weekly mowing needs). Trees are not in a constant state of growth, so you can’t apply a product at any time. Instead, trees go through a series of growth stages throughout the year.

Most of a trees annual root growth takes place in the fall. So, the fall is the best time of year to apply a conventional fertilizer. A conventional fertilizer consists of nitrogen-phosphorus-potassium. This is the kind of treatment that is going to directly stimulate growth. If you are going to directly stimulate growth for a tree it should be targeted toward the roots. There are other products you’ll need in your arsenal for a really great treatment regimen; see my Tree Treatment Products article for more information on this.

In the early spring trees are focusing most of their energy on foliage development. All of our native hardwoods produce an entire new set of foliage every spring. If you apply a conventional fertilizer when the foliage is growing you are going to wind up with abnormally large foliage. This can be a big problem if there isn’t a root system to support those oversized leaves. When our hot summer days get here you can get major heat stress and foliage burn from over sized foliage. Applying some humic acid and/or growth hormones during this time of year will help develop thicker, greener leaves. This is the direction you need to go. Thicker greener leaves will be better and conserving water when heat stress gets here and they will be better energy producers all year long.

Throughout most of the rest of the growing season trees in Austin aren’t growing much at all. This is primarily an energy producing time. The trees are getting ready for the fall’s root growing season and storing energy for next spring’s foliage development. Applying a fertilizer in the summer will likely not produce anything but fertilizer leaching into the adjacent properties and ground water supply. However, there are some specialized fungi you can apply in spore form to the soil that can help. They are called mycorrhizae (my-core-rize-ah). These fungi attach to the root system of the tree; they grow their own root like system; then, share what they absorb with the tree. This is a great way to improve the water absorbing ability of the tree during the hottest and driest time of the year. Another good thing you can do in the spring is apply humic acid to the soil. This stuff is the by-product of natural composting and is readily available to buy at most garden stores. It is usually sold as a “root stimulator” or “compost tea”. Look at the label of these products and you’ll see they contain a significant percentage of something that begins with “hum”.

And, don’t forget about diagnosis. You need to know the state of health of you trees before you can expect to keep them healthy. Look at my articles about sick trees.

Filed under: Fertilize — Keith @ 7:38 am

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August 10, 2009

Tree Fertilizer Part 1. An Introduction.

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.

Filed under: Fertilize, Sick Tree — Keith @ 7:34 am

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