Dormant (Winter) pruning has many positives! Depending on the tree or shrub, Zone 6 Winter pruning usually happens as early as February. Not only does the removal of dead/diseased wood help reduce the risk of falling branches, it improves the overall health and appearance of your trees. Plus, fresh pruning cuts and bruises typically heal faster during the dormant season.

Winters in Pittsburgh are tough! However, Winter does make one thing easier — pruning! Leafless trees allow Arborists to see their entire structure. Because each tree is different, pruning at the wrong time or in an incorrect way can cause irreversible damage.

Dormant Pruning has it’s Benefits!

One benefit of dormant pruning is that it enables us to correct disease problems when fungal/bacteria levels are lower in the colder months. For example, it is difficult to prune Fire blight from trees or shrubs during the highly infectious Spring or early Summer without spreading the disease to other limbs. During Winter, bacterial populations in trees are much lower and less likely to transmit by pruning utensils. Another example is Oak wilt. Oak wilt has become a disease of major significance in Michigan because of its pruning connection. Open wounds on trees during warmer seasons attract insects that carry these deadly fungal spores. Red oaks are often killed within a month or two after coming in contact with the fungus. Members of the white oak family may succumb in several years.

Dormant Pruning Saves Time & Money

Experts value time-efficient pruning solutions as much as you do! When the dormant season arrives, arborists have optimal access to trees that need pruning. Limbs are lighter and easier to handle, and leafless tree structures are easier to see. Since branching patterns are most visible in the winter, the core of the tree or shrub can be pruned to maintain a structurally sound form.

Gardenalia Tip: Pruning during the Winter months reduces the risk of fungal infections in trees and shrubs. The cost of replacing trees and shrubs is not cheap, so investing now can save you money later! We are committed to providing consistent pruning services during optimal dormant periods. Give us a call with any questions or schedule a consultation!

Oak Wilt Management Through Winter Pruning:

While many professional plant (“health care”) providers are aware of oak wilt and its potentially lethal effects on the trees, many are either unfamiliar with it or simply ignore the potential for oak wilt. Pruning during the summer months can actually promote disease transmission and the development of disease epicenters which can then devastate your landscape. The mechanism of disease transmission is that insect vectors (primarily sap beetles & picnic beetles) are attracted to wound sites, and they carry fungal spores from infected trees or dead logs to recently pruned trees. Luckily, some companies (like us!) have instituted winter pruning programs aimed at oak wilt management and other diseases.

When to Prune Oaks

From our perspective, the safest and most appropriate time to prune oaks is during dormancy — late October to early March. Timelines can vary from year-to-year depending on weather conditions, the type of tree or shrub, and other factors. One time variation surprise occurred during early March in 2000 Minnesota. Experts reported unexpected picnic beetle activity on March 1st. During most years they wouldn’t expect much (if any) picnic beetle activity during the first week of the month (or even through the rest of the March). This situation could have posed a problem for fungal outbreaks if the weather had remained warm. Keep in mind that during freezing/near freezing conditions, transmission of oak wilt is almost impossible.

Pruning Times Differ

Someone may recommend pruning during April, May, and June, and someone else — February and March. A common scenario with many oak trees is that they are large, 100+ years old, and in very prominent locations. They are simply irreplaceable. Ultimately, the likelihood of oak wilt transmission declines sharply after the three primary months. However, many scientists admit that they don’t understand all of the mechanisms or vectors of the fungal disease. Plus, no one will admit that the transmission of oak wilt is impossible; i.e., during the month of August. To add, a previous USDA bulletin noted that oak bark beetles may ALSO transmit oak wilt. Ultimately, these are a few reasons why we believe it’s smart to avoid any possibility of oak wilt and limit pruning periods to the dormant season.

Sanitization and Pruning

Oak wilt fungus can be transmitted by pruning utensils because of fungal material residing in sawdust or chips. This is especially true during the warm season when fungal growth is at its maximum. Sanitizing equipment between cutting trees is important too. However, there is no need to sanitize utensils between cuts on the sametree because it is either infected or not.

Benefits of Proper Pruning

The occurrence of dead wood is a common reason to prune oaks. It is not possible to prune dead wood without the exposure of a tree’s live tissue — which is why pruning needs to be completed dormancy vs. Spring or Summer to reduce fungal spread. Plus, proper pruning can help trees to become more storm-resistant.

Winterizing Plants for Better/New Growth

Ultimately, trees are healthiest when maintained during the dormant season and before new growth begins next Spring. Pruning after the onset of new growth can limit the plant’s bloom potential for the year. Also, dormant pruning pulls double-duty by causing less stress on trees and allowing for robust new growth in plants that bloom in the Spring and Summer.

In Summary:

• Trees are healthiest when maintained during dormant season
• Winter pruning has a smaller chance of spreading infectious disease or insects
• Removal of dead or diseased wood greatly reduces risk of falling branches
• Winter pruning saves time and money
• Pruning during winter improves the health and appearance of trees
• Dormant pruning prepares trees for Spring

[Excerpts from The Davey Tree Expert Company website (URL: www.davey.com) & http://treedoctor.anr.msu.edu/pruning/]