Did you miss our Oak Wilt webinar? No worries! Continue reading our Oak Wilt Webinar recap to catch up on vital insights about safeguarding your trees from Oak Wilt disease or click HERE to watch the full recording. The majestic oaks that grace the Niagara Region have stood as silent sentinels for countless generations. These trees offer shade, shelter, and stories for those who know how to listen. As with any great entity, these giants are not immune to the threats of the natural world. One of the most pressing concerns today is Oak Wilt. This is a lethal disease that threatens the health and survival of oak trees in North America. Safe Tree’s recent webinars aimed to shed light on this pressing issue. We brought together experts, enthusiasts, and every-day nature lovers in a collective effort to understand and combat Oak Wilt.
While the sessions were educational and enlightening, the sheer volume of questions and the limited time meant that many queries were left unanswered. But fret not! We’ve delved deeper, researched further, and gathered all those burning inquiries right here. Whether you’re a seasoned arborist or someone just beginning to appreciate the beauty of our mighty oaks, this compilation is designed to provide clarity on the mysterious ailment known as Oak Wilt.
Let’s venture further into the roots of this issue. Together, let’s strive to protect the oaks that have so generously given us their shade:
- Should we still plant Oak trees? Yes! Oaks are a native species to southern Ontario. Oak trees still need to be planted to encourage a polyculture filled urban forest. We do not suggest planting multiple oaks in close proximity to each other, though. If you are planting lots of trees close together, we highly suggest planting a variety of species.
- Rumor has it that mulching against the trunk can attract beetles and other insects. What is your view on this practice? How far away from the trunk should mulch be? It is not scientifically proven that mulch against a tree trunk attracts insects. However, if mulch is against a tree trunk for too long, it will cause decay due to moisture retention. Decayed wood will attract certain pests and fungi. We always recommend keeping all mulch a minimum of 2” away from the trunk of any tree, regardless of species.
- Are there more than 3 infected trees in Ontario? There may be other infected trees, but they are not diagnosed or confirmed at this time. It is best practice to report any potential oak wilt infections to the CFIA for proper diagnoses.
- Was climate change a factor in Oak Wilt coming to Canada? We’re not sure how oak wilt got into Canada – there are a few different possible pathways, but nothing has been confirmed by the Canadian Food Inspection Agency. Climate change could certainly have an impact on oak wilt distribution in the future. According to a study in 2020, southern Ontario is currently the most suitable habitat for oak wilt and a few of its vectors. But, it’s likely that the oak range in eastern Canada will become more climatically suitable within the next two decades. So oak wilt could spread through the range of red oak as temperatures warm with climate change.
- Can oak wilt spread to other trees? Michigan State University is investigating a case where chestnut trees were found to be infected with oak wilt and were showing signs of decline, including leaf wilting, however none of the infected trees has fungal mats or pressure pads. The study is still ongoing.
- How long can an oak tree live with oak wilt? Depends on species, conditions, etc. It is possible for white oaks to live for several years before succumbing to infection. Some trees with oak wilt might even recover from the infection. White oaks tend to develop symptoms slowly and, in some cases, they might carry the fungus but not show any foliar symptoms. Red oaks are much more susceptible, and they are more likely to decline within a matter of weeks after being infected. Bur oaks are somewhere in between – some are severely infected and rapidly die like red oaks. Other oaks decline and die much slower like white oaks.
- How will oak wilt affect the economic benefit of the urban forest? Urban forests, particularly in densely populated areas like southern Ontario, provide a host of benefits. These include property value enhancement, air pollution mitigation, stormwater runoff reduction, reduced energy costs and recreational opportunities. A loss of any percentage of oaks would negatively impact all the factors previously listed. This is because oaks are so prominent in our urban forest, specifically as large, mature trees. The percentage of oaks lost will be determined by the level of awareness, protection, and prevention we can provide as a community.
- How many cases are currently in Ontario? As of August 11, 2023, there are three confirmed cases in Ontario: One in Niagara Falls, one in Niagara-on-the-Lake, and one in Springwater.
- Can you tell us more about the chemical treatment being used in the US? Great question! This is such a large question, with lots of points to touch on. This will actually be its own blog post – coming soon!
- How susceptible are English columnar oaks to oak wilt? English oaks are part of the white oak group and are considered moderately susceptible to oak wilt.
- Can acorns be a problem regarding the spread of oak wilt? There is no evidence to suggest that this disease is transmitted by acorn stock.
- For cases of trees that survive after sealing over the infected area; so, they continue to carry the disease throughout the remainder of its life? Yes, the fungus will still be active, or alive, in the tree if the tree is able to live with the infection for a long period of time.
- Are there still symptoms of oak wilt shown within the tree after it begins to live with the fungus? Symptoms may be visible depending on the extent of the infection.
- It was mentioned that this fungal infection is like Dutch elm disease. If this Is the case, can we expect high mortality slowly creeping across southern Ontario? Oak wilt and Dutch elm disease (DED) are both vascular wilt diseases. There is an important difference on how both diseases have affected forests. DED has been present in Ontario for many decades, so there has been a lot of time for it to spread. It arrived at a time when invasive forest pest management techniques were not as well developed as they are today. To date, we have only had 3 known infestations of Oak Wilt in Ontario. We can benefit from the decades of oak wilt management experience from our American neighbours to manage oak wilt, so it does not have the same destructive effect on Ontario’s forest. Early detection and rapid response are key to this effort. Raising awareness about the disease is also best practice for preventing infection.
- Can infected wood be incinerated instead of being buried? Yes, infected wood can be incinerated as the fungus will not survive extreme temperatures. Infected wood should not be buried near any live oak trees to prevent spread of the fungus to healthy trees.
- For the case study in Belle Isle, were there any concerns about applying the fungicide with such high-watersaturation in the soil? No, there are no concerns regarding soil when applying this fungicide with a large amount of water. This is because the application method is injected directly into the root flare of the tree, and not in the soil. Therefore, the tree will update all the fungicide solution while none will enter the soil.
Do you have any more questions? Feel free to contact our Tree and Plant Health Care Specialists @ 289-650-1775 or info@safetree.ca.
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