Pruned Maple Tree is Dripping Sap?

Question:

I have a question. I have a Maple tree in my back yard, yesterday I trimmed some very small branches off the tree, when I say branchesthere were not much larger than twigs. Now the tree is dripping sap?Is this normal? I just hope I have not damaged the tree. Fortunatelywhen I saw what was happening I stopped. Any help would beappreciated. I live just south of Carson City, Nevada

Hardiness Zone: 6a

Peg from Minden, Nevada

Answer:

Hi Peg,

Don't worry about your tree. You haven't done any serious damage to it, but you were right to stop pruning once you noticed the sap starting to seep. Pruning wounds don't close as fast when sap is running. Sap flow this time of year is normal and hard to predict unless you're paying close attention to the weather. Here is a simplified version of what causes the sap inside maple trees to 'run'.

The tree sap that flows each spring was produced through photosynthesis the previous summer. Fluctuations in pressure inside the tree cause it to flow from the roots of the tree to its branches through an outer portion of the trunk called sapwood. Sap's function is to supply growing cells with nutrients. In the early spring, temperatures warm to above freezing during the day and usually fall back below freezing at night. The cellular activity that occurs in the sapwood during warm temperatures creates a build up of positive pressure inside the tree.

I remember the first time I walked out into my garden in the spring and saw one of my young sugar maples "bleeding" sap through several gashes on the trunk. I couldn't imagine who had it out for my trees. It turned out the gashes up and down the trunk were actually teeth marks. Squirrels love the stuff and know exactly when to pierce the bark for a delicious treat. Maple trees can be lightly pruned (removing a few small branches) anytime during the year, but it's a good idea to avoid doing it in the spring. Heavier pruning is best left to late winter or very early spring.

Ellen