Remember the especially noisy music of acorns crushing beneath your tires last fall? Perhaps you have apple trees on your property, and you just couldn’t keep up with all the fruit, no matter how many cobblers and crisps you made. Or maybe your yard was covered under an unusually dense blanket of black walnuts, which took much longer than usual to rake off the grass. These are all signs of a mast year! So, what causes a mast year, and what does it mean for your lawn and gardens?
A mast year is a little bit of a mystery. Every 3-5 years, all the trees in a particular region will synchronize and shift energy to produce more flowers and seeds. This yields a bumper crop, which leads to a massive harvest of larger fruits with more seeds. Some common mast trees include; oak, apple, spruce, cedar, hazelnut, walnut, and beech.
Some botanists attribute the mast year to communication between trees via chemical compounds transferred through root hairs, water, or the atmosphere. Trees could also be communicating through mycorrhizae, which is a fungus that grows underground amongst the roots of trees, in a symbiotic (or sometimes somewhat pathogenic) relationship. Still, other scientists theorize that mast years could be caused by pollen coupling, which is synchronization through pollen exchange between trees. Or perhaps the cause goes beyond the trees and comes from the external environment – predator satiation or particularly stressful weather like droughts or extreme temperatures one year could lead trees to produce massive crops the following year.
Whatever the cause, the results get mixed reviews. While farmers might be thrilled by the supersized profits, homeowners will have to clean up a bigger mess than usual. Squirrels, chipmunks, and beavers will be eager to stock away this welcome blessing, but lawns and plants will struggle for light and soil against blankets of nuts and armies of saplings. The mast year also has negative long-term health effects for the tree itself, often causing slower growth the following year and leaving the tree more vulnerable to stressful weather conditions.
When the first signs of a mast year begin to show, homeowners would be wise to consult with landscape professionals about including preventative measures and extra maintenance as part of their seasonal Organic Foundation Lawn Care Program. Tree seedlings and nuts should be removed from lawns and flowerbeds before they have a chance to take root and impede the growth of nearby plants and shrubs. This could mean adding extra raking and flower bed maintenance to your landscaper’s scope of work.
2023 was the most recent mast year in our region. This means the next mast year should take place between 2026 and 2028. It also means that 2024 could see unusually low yields at harvest time since the year after a mast year tends to experience a drastic dip in production. Novice farmers who are seeing their first mast year should do what they can to make the most of it, since the following year’s lower yields will also mean lower sales. Homeowners might look forward to this lower yield, still exhausted from all the mast-year raking. However, it’s also a good idea to protect your gardens, trees, and shrubs from backyard critters who could come in search of food that is scarce in the forests following a mast year.