What Comes After April showers?
Written by: Kyle Babicky, Certified Arborist/Certified Tree Care Safety Professional WI-0889A
We are closing the chapter on another Wisconsin winter. On the horizon emerges a season that many of us look forward to – springtime and the beautiful blooms that come with it! Some of the most majestic blooms in spring come from the wide variety of crabapples throughout the area.
During this wonderful season, there lurks an invisible enemy. Many of you are familiar with this pesky invader, a fungus called apple scab. Luckily, apple scab does not harm the blooms in spring. However, seeing such healthy blooms can distract us from noticing there is a disease already taking hold.
When apple scab infects a tree, it is not seen until it’s too late to correct for the year. The result is often a mostly bare tree and leaves scattering your yard already in summer. The tree also loses several weeks of making food for itself that it needs to store for future use.
It is crucial to be proactive with apple scab. The time to begin protection is when we are eagerly awaiting the spring blooms. Properly timed treatments every year are the best defense in helping your crabapple keep its leaves until fall. If you receive a customized annual Tree Care Prescription letter from our team of certified arborists, your early approval allows us to properly time your treatments.
Apple scab is an annual disease, meaning there is a new generation of spores every spring ready to infect new leaves. This means a tree must be treated each year to keep apple scab away. Fortunately, one season of apple scab will not kill a tree. If your crabapple had apple scab last year, you can avoid infection on new leaves this spring.
Proper treatments are the best defense against apple scab, but the following factors play a large role as well:
- Properly spaced branching helps to increase sunlight and airflow through a tree. This allows leaves to dry faster, creating better conditions to resist disease. Proper branch spacing can be achieved through professional pruning. A good pruning cycle for crabapples is usually three years depending on age and cultivar.
- Overall tree health is also important in resisting tree pests. Healthier trees often have thicker leaves, creating a stronger “wall of defense”. It is a good idea to have trees routinely inspected by a certified arborist to determine if there are issues with your tree that could make it vulnerable.
- Weather – No one has control over Mother Nature, but rain, wind, humidity, and temperature all play major roles in tree health. Trees need adequate soil moisture, but long periods of wet leaves mixed with warm temperatures allow apple scab to take hold. Also, arborists need to work around weather factors, such as rain and wind, to perform quality treatments.
Another factor to consider is the DNA of a tree. Some crabapple types are resistant to apple scab. No crabapple is immune, and resistance can fade over time, but some crabapples are resistant enough that their symptoms are minimal. If you are looking to plant a new crabapple, consult with your Certified Arborist to choose a variety that has higher disease resistance. If you’ve experienced apple scab on your trees in the past, or are interested in having your crabapples evaluated, please give us a call! We are happy to help keep your trees thriving in the landscape.