The product Ailantex, a biological agent for controlling the invasive tree of heaven (Ailanthus altissima), has been approved for use in Slovakia starting this year. This is a breakthrough in the fight against this aggressive invasive tree, which has spread to many areas of Slovakia in recent years, causing serious problems in natural habitats, urban edges, and protected areas.
Ailantex is based on a specific strain of the fungus Verticillium nonalfalfae (Vert56), which causes so-called verticillium wilt exclusively in the tree of heaven. This method was developed at the University of Natural Resources and Life Sciences (BOKU) in Vienna and tested for both effectiveness and safety toward other plant species. The product has been successfully used in Austria and several other countries for several years.
In Slovakia, the product has already been tested for an extended period as part of the LIFE Sub-Pannonic project – Restoration of habitats and species of sub-Pannonian grassland-herb communities. Positive results from this research use also helped secure approval for its wider application in the country. The main actor in the approval process was the company Biocont, experienced in regulatory procedures, which carried out all necessary steps to ensure the product was authorized for use in Slovakia.
Ailantex represents an ecological alternative to chemical herbicides—an ideal solution for sites where pesticide use is unsuitable or prohibited (e.g., near water sources or in protected areas). A major advantage is its ability to spread from an infected individual through the roots to surrounding shoots, allowing entire stands of invasive tree of heaven to be treated without the need to individually treat each tree.
In some cases, the first signs of wilting can be seen as early as two weeks. In this particular trial plot, only about four individuals were infected.
How to apply Ailantex
To apply the product, the following simple equipment is needed:
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Chisel (ideally with a hollow, U-shaped profile; the width and curvature of the blade should match the tree’s diameter)
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Mallet / wooden hammer
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Measuring pipette
The suspension is injected into the sapwood (xylem). Using the mallet, the chisel is driven about 0.5–1 cm deep into the wood at an angle of roughly 15°–20° above horizontal, forming a small reservoir between the blade surface and the handle.
In the second step, the desired amount of suspension is dropped onto the chisel using a pipette. The wound is slowly opened downward along the groove to accelerate absorption. The suspension is applied gradually, allowing the tree to draw it in.
For optimal distribution of spores through the vascular system, it is recommended to split the total amount of 3 ml per tree across 2–3 application points. These wounds should be evenly spaced around the tree’s circumference. From our experience, smaller amounts are sufficient for smaller trees—1 ml and a single notch may be enough for young saplings.
To ensure the best fungal spread and symptom development, applications should be done twice during the tree’s growing season: first in spring (May–June) and then at the end of the season (September–October). During these periods, the plant’s sap flow is most intense, which aids fungal distribution. Summer heat is unsuitable for fungal colonization, as Verticillium—like most fungi—is sensitive to drought and high temperatures. Maximum daily temperatures should stay below 25 °C, especially on sun-exposed areas.
The same area after 2 months.
Effect of the product
The tree of heaven’s vascular system distributes the product throughout the tree, creating localized mycelial colonies. From these colonies, enzymes and toxins are released, causing wilting and eventual death of the tree. With spring applications, the first symptoms usually appear within 4–6 weeks. For applications at the end of the growing season or on larger trees, the effects generally become visible in the following season.
Over time, the fungal mycelium spreads not only within the infected trees but also via roots (and soil) to neighboring individuals. Over 2–3 growing seasons, larger stands gradually die off. However, the overall progression of infection depends on many factors, including weather conditions, site characteristics, and the age of the trees.
In mature trees, the effects are visible only after a longer period. In this case, 1.5 years after treatment, most of the individuals in the trial plot had died, even though only about five mature trees had initially been infected.
Suitability of use
The product is a suitable alternative, especially in cases where herbicides are undesirable or their use is prohibited at a given site (e.g., near water sources, organic farming). It is particularly effective for treating large, dense stands, so-called polycormons. The product only needs to be applied to a portion of the trees, and the mycelium gradually spreads through the roots to all neighboring trees or sprouts. The fungus is expected to persist in the soil around the treated area, helping to prevent reintroduction of the tree of heaven.
Currently, the product is relatively expensive, but in polycormons the cost and labor required are significantly reduced. In these cases, it can quickly outperform conventional chemical herbicides in terms of overall cost.
The manufacturer recommends using the product within 2 months of opening the bottle. It must be stored in a cool place (6–8 °C) at all times.
More information about the product and its application can be found on the manufacturer’s website: www.ailantex.com
For questions about its use, you can contact our colleague Katka Mikulová: mikulova@broz.sk
In Slovakia, the product can only be purchased from the authorization holder, Biocont:
Ing. Pavel Mitáš
+420 733 186 591
mitas@biocont.cz