Urban and street trees are often "problematic children." They are exposed to drought, nutrient deficiencies, and pollutant stress. To remain vital and survive in the long term, they must withstand extreme site conditions such as high salt and heavy metal loads, low pH levels, severe soil compaction, and challenging water conditions. For more than 140 years, it has been known that trees living in symbiosis with mycorrhizal fungi benefit greatly from this partnership, enabling them to thrive even in extreme locations. Among urban and street trees, the lack of mycorrhizal fungi is most pronounced. A targeted application of mycorrhiza can support healthy tree growth, especially under stress conditions.

GEFA's mycorrhiza vaccine is not cultivated on sterile substrates but always grown on native plants. The result is a tree-specific, highly infectious mycorrhiza. Certain fungal species occur only in specific tree types. A fully functional symbiosis is achieved only when the appropriate mycorrhiza from GEFA Produkte® Fabritz GmbH is inoculated into the corresponding tree species.

• For new plantings
• Under high infection pressure
• During transplanting
• In the restoration of mature trees

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ECTO Mycorrhiza

Ecto = external

Among ectomycorrhiza, there are edible species (truffles), inedible ones (bitter russula), and toxic types (fly agaric). Almost all form fruiting bodies and can be seen with the naked eye on fine roots.

Typical symbiotic partners: oaks, beeches, hornbeams, firs, spruces, pines, and some other tree species. Linden, poplar, and willow can form or host both ecto- and endomycorrhiza. However, older trees and drier soils tend to favor ectomycorrhiza.

ENDO Mycorrhiza

Endo = internal

With around 80%, endomycorrhiza is the most common form of mycorrhiza among all land plants, formed by zygomycetes (Glomales). Changes to the fine roots are not visible externally. These fungi do not form fruiting bodies, and their spores are so tiny that they must be observed under a magnifying glass.

Typical symbiotic partners: maple, plane tree, horse chestnut, and fruit trees.

Mycorrhiza

THE HISTORY OF MYCORRHIZA

Knowledge about mycorrhiza dates back more than 140 years. At that time, the Berlin botanist Prof. Frank was commissioned by the King of Prussia to cultivate truffles. During his work, the forestry specialist observed that the fruiting body of truffles was always connected to the fine roots of certain tree species. These roots consistently exhibited a characteristic appearance: they were more compact, highly branched, and displayed a different color compared to 'normal' roots. However, not only edible fungi serve as tree partners.

There are many other fungi capable of forming such symbiotic relationships. Some are inedible (e.g., the Paxillus involutus), while others are toxic and therefore not propagated by us (e.g., the fly agaric).

All these fungi form what is known as ectomycorrhiza (ecto = external). They are visible to the naked eye and typically develop proper fungal fruiting bodies. Since these truffle roots were not ordinary roots, Prof. Frank named them mycorrhiza, derived from the Greek words mykes (fungus) and rhizos (root).

MYCORRHIZA

WATER ABSORPTION

Fungi, with their delicate mycelial network, are particularly adept at absorbing water. This is made possible by far-reaching hyphae, which increase the absorbing surface area by 100 to 1,000 times. Additionally, fungal hyphae, only 2-3 micrometers thick, can penetrate the micropores of soil. In these pores, they extract water that would otherwise be inaccessible to plants without fungal partners.

Compared to root hairs, which are single-cell extensions of fine roots, fungal hyphae extend much further into the surrounding soil and are significantly thinner.

A robust mycorrhiza greatly enhances the water supply to plants. This can be a decisive factor in the success or failure of new plantings and significantly contribute to the revitalization of mature trees during restoration!

MYCORRHIZA

NUTRIENT ABSORPTION

In addition to significantly improved water absorption, all nutrients dissolved in the water are also transported to the plant in much higher quantities. This often occurs via specialized transport structures, called rhizomorphs, which resemble root structures and can grow over a meter in length.

Furthermore, mycorrhizal fungi have the ability to secrete enzymes and organic acids, which improve the uptake of phosphate, nitrogen, potassium, calcium, magnesium, iron, and other micronutrients. These substances can also be extracted from organic and mineral compounds. A large portion of these nutrients is directly supplied to the partner plant, while another portion is stored and can be released during times of deficiency.

This enhanced nutrient supply, particularly of nitrogen and phosphate, enables trees and shrubs to thrive in locations where survival would otherwise be impossible without fungal support.

MYCORRHIZA

PROTECTION FROM TOXIC METALS

Mycorrhizal fungi can significantly reduce the toxicity of heavy metals for plants by binding them through chemical processes, such as the formation of chelates outside the cells, and by fixing them in cell walls. This allows plants to survive even in soils that would typically be toxic.

Similarly, harmful trivalent aluminum can be permanently bound, significantly reducing the risk of poisoning in highly acidic soils.
This demonstrates how mycorrhizal fungi help plants survive in contaminated soils by neutralizing toxic substances.

MYCORRHIZA

PROTECTION FROM HARMFUL SOIL ORGANISMS

Many mycorrhizal fungi protect plants from harmful organisms by producing antibiotic substances. Similar to molds like Penicillium or Trichoderma, they secrete compounds near the mycorrhizal fine roots that inhibit or kill harmful bacteria and fungi, thereby protecting the roots from infections.

Another protective mechanism occurs when mycorrhizal fungi penetrate the roots, triggering defense responses in the plant. These responses make it more difficult for pests to cause infections or feed on the roots. This protective process is known as pre-immunization.