Many Minnesotans have reported seeing abundant amounts of maple helicopter seeds this year. When the seed or fruit of long-lived trees are seen in copious amounts, similar to current reports, this is known as a mast year, or masting, for that tree.
Seed production occurs every year in varying amounts. However, research on masting indicates the phenomenon appears every 2-5 years. Additionally, a mast year may be stimulated by ideal pollination conditions or environmental cues like moisture and temperature.
Signs of masting include witnessing large amounts of fallen floral parts followed by the seeds a few weeks later. The flowers are typically a shade of red (red and silver maples) or yellow-green (norway and sugar maples) and appear before the leaves emerge. The fruit, commonly known as a helicopter, is actually a winged nutlet called a samara. Samaras are typically 1-2 inches in length and are initially red or green color, maturing into a light brown.
Masting provides animals like squirrels and birds to abundantly feed on the small fruits. The addition of many seeds may also keep the genes of the tree alive within the environment.
The seeds are carried by wind. Therefore gardens, lawns, sidewalk cracks and even gutters may provide habitat for a seedling to grow. For gardeners with maple trees nearby, this may result in more weed pulling. With some trees, like sugar maples, a mast year will initiate low sap production the following year.
On the tree, a mast year may initially stunt the growth of leaves. This is because energy was shifted to supporting heavy seed production. It may make the tree look unhealthy initially, but now that the seeds are dropping or have dropped, the tree should begin exchanging energy back into the leaves.
A distress crop may be mistaken as masting. When a tree produces a stress crop, it is putting all of its energy into seeds to create the next generation. A tree may do this if it is experiencing stressful growing conditions.
To examine a tree for distress, look for stem girdling. This is when roots around the trunk squeeze and compress the correct flow of water, nutrients and sap of the tree. Other issues can come about from poor soil conditions or trunk damage. To minimize environmental stress, it is important to keep trees watered during drought.
Though there are no methods to prevent masting, there are things to do with the abundance of seeds. Consider starting a journal to track your trees’ masting.
For more information regarding tree masting, please visit extension.umn.edu and search “mast.” Wright County residents can call 763-682-7394 for questions related to tree health or other related yard & garden items.