Arbotect 20-S
Scientifically proven systemic fungicide that provides multi-year protection from Dutch elm disease and beech leaf disease.
Product details
Arbotect® 20-S is a scientifically proven systemic fungicide designed to protect elms from Dutch elm disease (DED) and beech from beech leaf disease (BLD).
In Canada, Arbotect 20-S is registered by Health Canada’s Pest Management Regulatory Agency (PMRA) as a preventative treatment against Dutch elm disease. It currently has an emergency use registration for beech leaf disease in Ontario from July 4, 2025, until July 3, 2026 (PCP 16694).
Macro-infusion rapidly introduces a large volume of solution directly into a tree’s vascular system, evenly distributing the solution throughout the tree’s canopy.
Modes of Action
- DED: Arbotect 20-S suppresses the fungal pathogens Ophiostoma ulmi and Ophiostoma novo-ulmi, preventing colonization of water conducting tissues. It moves effectively into young elm branches where elm bark beetles introduce DED.
- BLD: Arbotect 20-S reduces the impact of the foliar feeding nematode Litylenchus crenatae spp. mccannii, slowing disease progression. It reaches beech leaf tissue where BLD causing nematodes are found post leaf flush.
Key benefits
Multiyear Protection
- Protects elms from DED for up to three growing seasons.
- Provides two seasons of effective protection against BLD.
Proven Performance
- Over 25 years of documented success and 99% effectiveness when used as directed for DED prevention.
- Currently the most effective treatment option for reducing BLD severity.
Complete Canopy Coverage
- Arbotect 20-S is delivered directly into the tree’s root flares using macroinfusion, allowing even and thorough product distribution.
Ingredients
Thiabendazole 20%
Formats
| 1 gallon | Storage information: Store in a cool, dry place, away from direct sunlight, at room temperature. Unopened bottles have a three-year shelf-life from date of manufacture. |
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About Dutch Elm Disease (DED)
DED is caused by two strains of an aggressive fungus that kills elms regardless of their health. The fungus invades the water transporting tissues and produces toxins to which the tree reacts by producing gums and internal growths designed to block the advance of the fungus. This inhibits water and nutrient flow to the crown, which causes wilting and eventual tree death.
Prevention of DED
One application of Arbotect 20-S protects the entire tree for up to three years yielding significant cost savings. The most common method of transmission of DED is on the bodies of elm bark beetle who feed on two to four year old branches. There are multiple generations of elm bark beetles per year. Thousands of beetles may hatch from a single tree.
Multi-year control prevents transmission by elm bark beetle at peak flight times early in the growing season. To protect a tree from a beetle-transmitted fungal infection, Arbotect 20-S must be evenly and completely distributed throughout the two to four year old branches. To ensure even distribution, Arbotect 20-S is injected using the Macro-Infusion injection method. Macro-Infusion injects a large volume of solution into the root flares of the tree. This solution is then transported throughout the canopy providing a protective fungicide barrier.
Only Arbotect 20-S has the ability to move into the newly formed sapwood, while resisting degradation resulting from cold, heat, and other adverse conditions.
Arbotect 20-S was first registered over 30 years ago and has a proven 99% success rate when applied as per manufacturer’s directions.
DED Treatment & Timing
Applications can be made after leaves have fully flushed in the spring. Treatments can continue throughout the growing season, or until fall colour begins.
Treatment should be used in conjunction with an insect control and sanitation program (early detection and rapid removal of infected trees) in order to obtain best results. Use of Arbotect 20-S does not prevent the transmission of Dutch elm disease via root grafts.
About Beech Leaf Disease (BLD)
BLD was first identified in Ontario in 2017, in Elgin County, and has since spread throughout most of the regions in southern Ontario, affecting natural and planted landscapes, including nurseries. It has also spread across much of the northeastern US. The disease affects beech trees of all sizes, from saplings to mature specimens, and can cause mortality in young trees within just a few years.
The primary species impacted by BLD is American beech, though cases have also been reported in European beech and other ornamental varieties. American beech is distributed across Eastern North America, but various species of beech may also be planted outside this range.
Ongoing research indicates that the damage is caused by an invasive nematode, Litylenchus crenatae ssp. mccannii. These microscopic worms inhabit the leaves and buds of beech trees. The damage begins inside the buds, and when those buds leaf out, the damage is visible as banding between the veins in the foliage, where nematodes continue to feed through the summer. Leaves may also become shrivelled and drop prematurely. Infected trees can also exhibit branch dieback and become more susceptible to decline due to other factors.
Research continues to investigate how the disease spreads.
BLD Treatment & Timing
One application of Arbotect 20-S protects the entire tree for up to two years. Treatment should be used in conjunction with insect control and sanitation programs (pruning of diseased limbs) to obtain the best results.
Applications should be made after trees are fully leafed (post-infection) through summer or early fall. Refer to the emergency use label for full application instructions.
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