Tree Stressors and Tree Decline

People aren't the only living thing that can get stressed - trees can too. In fact, tree stress is a serious problem that not only causes significant damage to your trees but also can kill them.

So what causes trees to get stressed? The first is environment. Just like humans, the environment we are surrounded by affects trees. Stressful environmental conditions such as extreme temperatures, poor soil, and physical damage to leaves, bark and roots can predispose a tree to secondary insect and disease attacks. Extremely wet soil can also stress a tree as can soil compaction and freezing.

Trees are also surprisingly affected by other conditions that are caused by man or animal. For example, lawnmowers are one of the major causes of damage to trees. Improper pruning also stresses trees. Too much pruning or pruning during the wrong time of year can harm your tree more than help it. Over watering trees also causes trees great stress, just as flooding or too much rain could. Frequent watering results in roots that are too wet for good growth.

Other human caused stresses are improper handling before planting your tree, construction damage and the use of deicing salts or herbicides. Tree wounds caused by humans can also make your tree quite susceptible to outside influences and therefore make the tree deteriorate over a period of time.

The problem with tree stress is that from the human eye, you may not recognize that your tree is stressed right away. Of course there is obvious stress such as that caused from storms, but the small stresses are also very critical to a trees survival as well. Trees often do not display immediate responses to stresses because of their accumulated growth habit. But when your tree is stressed you will begin to notice that it will change. In some cases, the process of photosynthesis, which is the primary supply of carbohydrates for all tree functions, is reduced and the tree’s stored food reserves are depleted. And if the root systems are also damaged, the tree will be unable to produce sufficient carbohydrates and growth regulating chemicals.

Symptoms of distress will begin to show as your tree deteriorates. The leaves may decrease in number and become smaller in size. Some trees will produce excess fruit or seed - this is its way of trying to survive. Branches will begin to die, and the root system of the tree becomes reduced. From here the tree will continue to decline until the eventual death of the tree, which can take from 2 to 15 years. For many trees, once the decline has reached a certain point, it cannot recover.

If the actual physical stressors to the tree don't kill it, the reduced strength of the tree will leave it vulnerable to disease and insects. The addition of these elements can speed up the trees decline.

Trees in urban areas are often stressed more than those that are in rural areas - this is due to restricted root space, building foundations, streets, driveways and other obstacles that limit the expansion of tree roots and significantly reduce the amount of water and minerals available to the tree. Compacted soils and competition also stresses urban trees.

If you feel your tree has been recently stressed, consult with your local tree professional or arborist for some proactive measures you can take. Trees can be quite resilient and with a little care, they can potentially make a full recovery.


Andrew Johnson is the owner of Central Texas Tree Care, a leading tree service provider in Central Texas (Travis County and surrounding areas) offering services such as pruning and removals, cabling and bracing as well as arborist reports, diagnostics, pest management, fertilization and Austin tree service trusts. For more information please visit http://www.centraltexastreecare.com.

Preparing Your Trees For Summer Storms

Summer storms can hit hard, in desert climates they are often called monsoons and last from June to the end of September. During the storms one can see high winds, lightening and damaged trees. So how can you protect your trees from summer storms?

There are many things that can happen to a tree during a storm. To start, if there is heavy rain, a tree may be even more vulnerable when the wind follows. The reason is due to the ground being overly saturated, which can cause even a tree with healthy roots to weaken its hold. In this case, the bulk of the root system will become exposed if the tree falls over. Trying to protect your tree from falling over in a storm is difficult but there are some ways you can prepare your trees from possible damage.

FEMA (Federal Emergency Management Agency), states that "Three-fourths of the damage that trees incur during storms is predictable and preventable." These are the defects they say to watch out for that make trees more vulnerable to wind and other severities of the weather:

* Dead wood is unpredictable because it is brittle, and cannot give under pressure like living tree branches.
* Cracks are clear indicators of potential branch failure, where there will be splitting sooner or later.
* Look for excessive leaning, long horizontal limbs, crossing branches that rub against each other and create wounds, and narrow crotches (V-shaped instead of U-shaped). Multi-trunked trees need special attention and care. Two trunks or leaders that are of identical diameter and have a narrow crotch are not a good sign. To prevent splitting, choose one to be made dominant by stunting the growth of the other through pruning (called subordination).
* Decay, as evidenced by fungal growth or hollow cavities, is a sign of weakness.
* Pests, which can exacerbate a tree's health problems, but they typically target trees that are already sickly.
* Root problems, such as stem-girdling roots, while sometimes harder to detect, have the most impact on a tree's inability to stay upright. Weak roots and a thick canopy is the deadliest combination during a storm. Keep in mind that roots are a tree's anchor. If a significant portion of a mature tree's roots have been crushed or cut, or if the tree is still root-bound from the box it came in from the nursery before it was planted, you may consider removing the tree before the wind or weather moves it for you (without warning).
* Keeping your trees thin is the single most important thing to do to "storm-proof" them. Quite simply put: the thicker a tree is, the more susceptible it is to damage in heavy winds. Even for a tree that is otherwise perfectly healthy, overly dense foliage poses a safety hazard during stormy weather. A dense canopy will not allow the wind to easily pass through, and the resistance to wind can cause branches to break or even bring the entire tree down. This especially applies to weight at the ends of branches, which is why stripping only the lower parts of the branches is not adequate (and leaves the tree with a funny lion-tailed look).
* Plant new trees with their mature size in mind. Do not plant in shallow soils, too close to buildings or wires, or in steep banks. Some trees are more brittle and susceptible to breaking.
* Water, mulch, and fertilize the trees regularly and properly. Prevent the soil from becoming compacted.
* Prune annually (or every two to three years, depending on the variety) even while the trees are still young. Having your trees trimmed by a professional who understands healthy tree structure is your best bet for avoiding problems.
* Avoid excavating around roots. If some excavation is necessary, take measures to minimize cutting or any other impairment of the roots.
* Do not top trees! This common but incorrect practice guarantees eventual failure of branches.

Your trees will receive the best care from a Certified Arborist. An experienced arborist can quickly recognize potentially hazardous defects in a tree before they become major threats. If left to worsen, these defects can lead to branch failure, splitting, or loss of the entire tree. Keep in mind, though, that it is not only your arborist's responsibility to care for your trees. There is a lot you can do, too.

Andrew Johnson is the owner of Central Texas Tree Care, a leading tree service provider in Central Texas (Travis County and surrounding areas) offering services such as pruning and removals, cabling and bracing as well as arborist reports, diagnostics, pest management, fertilization and Austin tree service trusts. For more information please visit http://www.centraltexastreecare.com.

A Trees Need For Nutrients

If you own trees or plan on planting trees – understanding their need for nutrients is vital. All trees require the right amount of nutrients to live and thrive. If even one or more of these nutrients are deficient in the soil, the tree will not reach its full landscape potential, will be more susceptible to disease and insect problems, and will have a shorter life than a similar, well-fertilized tree.

To understand the nutrients trees need, one first looks out how these nutrients are divided into two groups: macronutrients and micronutrients, based upon the quantity necessary for growth. Macronutrients are required by plants in larger quantities than micronutrients. Macronutrients include nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S).

Micronutrients, which are required in very small amounts, include iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), chlorine (Cl), and molybdenum (Mo).

Many fertilizers are designed with the right amount of nutrients in the right proportions, which helps to take the guesswork out of fertilizing. All fertilizer labels indicate the amount of nitrogen, phosphorus, and potassium contained in the product by percent. These labels also indicate the weight of these nutrients per 100 pounds of product. For example, 100 pounds of a fertilizer marked 10-8-6 contains 10 pounds of nitrogen in various forms [eg. ammonium (NH4) or nitrate (NO3)], 8 pounds of phosphate expressed as P2O5, and 6 pounds of potash expressed as K2O. Fertilizers containing N, P, and K, such as 9-18-9 and 20-20-20, are referred to as “complete fertilizers”.

If you are trying to stay completely organic, fertilizers are offered in this form as well. Organic fertilizers take time to break down and release nutrients more slowly.

To determine when to fertilize or how much, take into consideration your environment, whether your trees have been under stress due to low moisture, whether they have been damaged physically. Competition by nearby turf and trees can cause stress on your trees. And if you have just planted your tree, it is important to keep weeds away from their bases to avoid excess stress.

Another way to determine whether your tree needs fertilized is to do a soils test by taking a sample. Ideally, a soil sample should be taken before trees are planted. Additional samples can be taken every 3 to 5 years thereafter to determine whether any nutrients are lacking. A soil test kit may be obtained from your county extension service.

In the absence of a soil test, the best indicator of the need for additional fertilization of established trees is shoot growth. If new shoot growth (growth occurring in the present year) is in excess of 6 inches, then fertilization is probably unnecessary. If shoot growth is between 2 and 6 inches then fertilizer may be applied.

Foliage color is another indicator of the need for fertilization. Yellow or “off-color” leaves may indicate the need for fertilization as these symptoms generally occur on trees, which are not taking up enough of one or more required nutrient. Always remember, however, that apparently “off-color” leaves are normal for certain plants such as ‘Sunburst’ Honeylocust and some maple and ash trees in the fall.

A final indicator of the need for fertilization is the history of the yard. Trees in yards that are fertilized for turf on a regular basis rarely need to have supplemental fertilizer applied. Supplemental fertilizer should only be considered if shoot growth is less than two inches, or if a soil test reveals a specific nutrient deficiency.

When should you fertilize? Most trees experience a single flush of growth during spring followed by slower growth throughout the summer and fall. Because of this single flush of growth, it is desirable to have nutrients available to the tree as this growth is about to occur. The most beneficial time to apply fertilizer is from when the ground is workable in the spring until just before trees start growing in early May. On sandy soils, applications should be split, half in early spring and half in mid- to late May.

If you have trees, put them on a schedule, monitor when you have fertilized and any changes. And remember, it is vital for their healthy growth.

Andrew Johnson is the owner of Central Texas Tree Care, a leading tree service provider in Central Texas (Travis County and surrounding areas) offering services such as pruning and removals, cabling and bracing as well as arborist reports, diagnostics, pest management, fertilization and Austin tree service trusts. For more information please visit http://www.centraltexastreecare.com.