As the summer warmth fades and September rolls in, tree care professionals like Joel Kosa, an ISA-certified arborist and owner of Boreal Tree Solutions, prepare for the busiest time of the year. “September often translates into a significant uptick in service calls, giving us plenty to do until mid-December,” Kosa explains.

Tree pruning becomes a top priority for many homeowners during fall, as they look to tidy up their gardens and prevent potential damage. For example, Kosa shares how one homeowner expressed concerns about overhanging branches jeopardizing their roof shingles, highlighting the importance of hazard mitigation. “Dead trees or limbs leaning dangerously over properties can cause serious damage during winter storms," Kosa warns. "Homeowners should look to address these concerns before the onset of snow and wind.

With the cooling weather, arborists can safely prune more mature trees, such as oaks and elms, as they face less stress in the absence of summer heat. However, homeowners should remain vigilant against pests and diseases that may crop up as well. This year, Kosa has witnessed an alarming rise in apple scab, particularly impacting apple and crabapple trees throughout Winnipeg. “I've never seen it spread so widely in all my years in the industry,” he reveals.

Apple scab, a fungus responsible for unsightly dark spots on leaves, thrives in wet and humid conditions. This year’s excessive spring precipitation has created a perfect environment for its expansion. Proper management in fall is essential because the fungus can survive winter on fallen leaves and fruit, making it crucial to eliminate infected material—although this can be a challenge, especially with mulch around trees.

Kosa suggests a combination of pruning and fungicide treatment to manage the fungal infection. This process can encourage healthy growth and mitigate further damage. Partnering with Dayne Anderson of TreeHuggers Tree Care, Kosa emphasizes the importance of tailored treatment strategies, which may include multiple applications of fungicides and specific fertilizers to enhance the trees’ immune systems.

“Even if conditions improve next spring, previously infected trees may still show signs of illness,” Kosa cautions. “Trees, like humans, can carry the lingering effects of sickness.” This reinforces the need for sustainable and proactive tree care.

Moreover, Kosa points out that oak trees in Winnipeg face their own set of challenges. The emergence of oak decline—a condition affecting bur oaks—illustrates how stress can make trees vulnerable to pests like the two-lined chestnut borer. “We must ensure we accurately diagnose the problem, as these trees can be sensitive to multiple stressors," he notes.

Kosa details the diagnostic process, which includes careful sampling of branches to search for signs of beetle infestation. Managing these threats involves a meticulous approach, including a two-stage process of both pruning and insecticide injection using TreeAzin, a method that has proven effective.

Beyond aesthetics, the care for trees is crucial for ecological balance and mental well-being. Trees play a vital role in absorbing moisture, shading landscapes, and lowering energy costs. They also provide undeniable emotional benefits, making their maintenance a priority for communities.

As autumn approaches, Kosa urges homeowners not to delay in seeking arborist assistance upon noticing signs of tree distress. “Just like our bodies, trees have immune systems that can falter when under stress,” he emphasizes. “By acting early, we can help maintain their health, ensuring they can withstand any challenges that lie ahead.”

Stay proactive this season—your trees depend on it!