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Tree Care: A Secret Weapon .. . Mycorrhizae

| Tree Care

6_3.jpg Weapon of choice There are all kinds of ?enemies? lurking about, ready to bring down a transplanted tree or stop another from growing. But you, the hero, are not without weapons. Most heroes are already well equipped to deliver water and fertilizer and rescue a tree from pest and disease control.

But there is another weapon of choice that some heroes forget: mycorrhizae. Perhaps these powerful forces are often overlooked because they are so tiny, but these naturally- produced fungi help a plant in all stages of its life cycle.

Mycorrhizae are fungi that form mutually beneficial, symbiotic relationships with plant roots. After the mycorrhizae colonize and begin to multiply, they essentially act to increase the root area and volume by acting as extensions of the roots. The symbiotic cycle between roots and mycorrhizae results in improvements to not only the root system, but also the color, foliage and overall health of the tree.

While there are as many as seven forms of mycorrhizae, the two most common groups are ectomycorrhizae and endomycorrhizae. Ectomycorrhizae are associated with 10% of the world?s plants, primarily trees such as pines, birch, oak, walnut, willow and beech.

Ectomycorrhiza fungi colonize the outside of roots and create a sheath of hyphae (fungal cells) that increase the root surface and volume, thereby improving the uptake of resources such as water and nutrients.

Endomycorrhizae, or arbuscular mycorrhizae, colonize inside the root and are characterized by two structures: vesicles and arbuscules. Vesicles are used for the storage of carbon. Arbuscules are where the nutrient exchange between the fungus and plant actually takes place. Endomycorrhizae form beneficial partnerships with 70% of all plant families, including flowering plants, annuals, grasses, and select trees such as maples, magnolias and dogwoods.

Like ectomycorrhizae, endomycorrhizae help increase establishment and growth, expand the roots? surface area, improve resource acquisition and tolerance to soil problems, and generally boost resistance against stress.

In fact, research shows that plants receiving a mycorrhizae supplement can experience an 18-fold increase in total root surface. Trees, in turn, provide carbohydrates that the mycorrhizae need to thrive.

Heeding the call

A good hero knows that his weapons must always be at the ready, for you never know when an enemy will strike. But you must also understand which weapon should be used in certain circumstances.

For example, soil moisturizers can help retain water in a drier environment, but might work so well that plants develop root rot. Similarly, a stimulant can bring back a stressed and wilting plant, but it?s better to keep the plant from getting to that stage in the first place. Excessive fertilizer can actually hurt a tree by reducing the benefit provided by soil microorganisms such as mycorrhizae.

While mycorrhizae occur naturally, soil and plants often have severely reduced populations of the fungi due to outside forces such as construction, transplanting or weather. Thus, the hero should maximize the opportunities to reintroduce mycorrhizae into a tree?s environment.

When mycorrhizae are applied to a tree, they act as a constant supplement throughout establishment, growth and the adult lifespan, helping build up the health of a plant but also sheltering the tree during times of stress. Mycorrhizae have three primary functions: 1- Combat environmental stress and strengthen a plant to increase survival rates. 2- Ease the transplant process by providing support during what can be a difficult transition. 3- Increase nutrient and moisture uptake and phosphorus accumulation, thereby improving health and, most importantly, appearance.

Ready . . . aim . . .

Trees are often at the mercy of their less-than-perfect environments. As the hero of this story, it?s your job to help trees defend them selves against terrors such as ravaged soil, harsh weather?and even people.

Don?t let your clients become a tree?s enemy. Remember to counsel them to choose an installation site that is not only attractive, but also one that is conducive to the tree?s survival. Establishing a tree where it will have adequate access to sunlight and water will help start a tree on the right track. Helping clients choose the ideal type of tree for their climate and soil type will also increase the survival rate.

But even with a knowledgeable choice, some locations are not as perfect as others. And all are at the mercy of unexpected weather. Mycorrhizae increase tolerance to a wide variety of environmental extremes such as drought, salty irrigation water or soils, heavy metal toxicity, and waterlogged, compacted or anaerobic soils. Adding mycorrhizae as a preventative can help protect a tree in such cases.

While not as unexpected, the impact of humans can also be significant. Trees in commercial or urban locations may undergo stresses from foot traffic, space limitations, paving or concrete confinements, or surrounding materials. Construction, tillage, compaction, erosion, pesticides and even fertilization can negatively impact soil and harm the supportive fungi on which trees depend; therefore, inoculating with mycorrhizae is very important.

But beware?even a vigilant hero may not recognize the signs of environmental stress until it is far too late. Damage may not become visible for years, making regular supplementation for even ?healthy-looking? trees important. And these victims don?t verbally cry for help. Preventative treatment gives the mycorrhizae the greatest chance to help the tree before irrevocable damage is done.

9_1.jpgTo the rescue

Transplanting can be a dangerous time?a time when a tree may need a hero to step in and provide protection and extra resources. Mycorrhizae facilitate plant establishment more quickly by helping roots retain moisture and enhancing stress tolerance.

When a normal or stressed tree undergoes a move, it depletes the resources it has, meaning that the normal tree becomes weak and the stressed tree becomes dangerously exhausted. These stressed conditions decrease the plant?s chances for survival and require an extraordinary amount of additional water and resources.

With the assistance of mycorrhizae, a tree can maintain a higher level of health and therefore not see such dramatic effects during a move. You?ll be quite the hero of not only the tree, but also your business? time and money, since stronger trees require less frequent follow-up maintenance and decrease the chance of transplant losses and subsequent replacements.

Even a hero needs a little help sometimes. Providing trees with mycorrhizae during the transplant and establishment phases reduces the chance that you?ll have to expend your own extra resources in recovery efforts. A little extra ?insurance? for survival is particularly valuable for trees in commercial, urban or otherwise ?hands-off? environments. Often in these situations, suffering plants may not be reported to you until too much damage has occurred, leaving you with replacement as the only option.

?It?s Super Tree!?

You may not consider yourself a hero with superpowers. But you have the ability to provide a tree with ?superpowers? of i t s o w n when you add mycorr h i z a e . A tree?s health is reliant on its feeding system to b r i n g i n m o i s t u r e and nutrients; mycorrhizae boost the ability of the roots? system exponentially and increase the tree?s ability to retain phosphorus.

Because mycorrhizae are smaller (1/10 the diameter) compared to roots, they increase the ability of the roots to access nutrients in the narrow spaces between soil particles. This ability can increase the absorption of nutrients by up to 60- fold, ultimately resulting in an increase in total absorbing capacity of the root over its lifetime. Mycorrhizae- treated roots also spread to form an extensive cobweb-like network that covers a larger soil volume than normal roots.

Some research has suggested that plants growing near each other actually link through mycorrhizae, which can transfer nutrients between the plants. There is also evidence that mycorrhizal roots live longer than plant roots not colonized by mycorrhizae.

In addition, mycorrhizae allow roots to absorb phosphorus more quickly, stimulating growth of both the root system and the tree itself. The growth increase also encourages flowers to grow more quickly and extends the growing season by providing fruiting trees with earlier yields.

10_1.jpgThe End

A hero knows that saving the day might take any number of wellthought- out plans or cool gadgets or weapons. The plan? Add mycorrhizae. The tools? Endo- and ectomycorrhizae are available in dry soluble powders, granular pills, tablets or pre-inoculated soil media. Delivery methods include soil drenching, liquid injections, granular incorporation, vertical mulching and even ground spikes for year-round tree feeding.

Applying a mycorrhizal product to established or newly transplanted plants can result in a wide range of benefits to the plant?s health, including increased nutrient uptake, increased resistance to insect pests and diseases, reduced use of traditional fertilizers, increased accumulation of phosphorus, and increased transplant survival.

The trees will show their thanks with color, healthy growth and a long life. Your human clients will send you off with a big ?thank you.?

?Just doing my job,? you say, tipping your hat as you ride off into the sunset.

 
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