Wait and See
With warming temperatures this week it would seem that we are finally getting into the home stretch of one of the fiercest winters in recent memory. In case you spent the winter in some tropical setting (if so, hats off), the weather of the last couple months featured just the sort of tests that push plant material in our turf and landscapes to the limit - frequent heavy snowfalls, high winds, and intensely bitter cold.
With record shattering snowfall amounts, especially in the Eastern portions of Massachusetts, it will still be a bit yet before we learn exactly the kind of shape that our turf is in. On the plus side, snow is an excellent insulator for turf, and we have had an extended period of snow cover that was present through much of the severe cold thus far. Snow helps to buffer against extreme temperature fluctuations, and can help to prevent mid-winter de-acclimation in the event of a ‘January thaw’ situation (fortunately not a big factor in our region this winter). A snow cover also provides a barrier against desiccation injury from drying winter winds and very low dew points. Drawbacks of prolonged snow cover, however, include increased incidence of snow molds and damage from critters such as voles that have a field day under the protection that snow provides.
A point of concern is the transition into winter, and the fall hardening period could have been a little better. We had mostly great grass-growing weather in September and October and started on a nice gradual decline toward winter dormancy in November. After a brief taste of winter around Thanksgiving however, December was rather mild, especially towards the end of the month. In fact, temperatures touched 60º in some locations on Christmas Day, soon after which we plummeted into the deep freeze.
Free water at the surface and in the upper soil profile can promote hydration of the vital turfgrass crown, especially in conjunction with milder temperatures, which sets up grasses for low temperature kill when temperatures drop off. Precipitation in October was 3+ inches above average in many locations, 2+ inches above average in November, and 3+ inches above average in December, so the there was plenty of moisture to go around. Perennial ryegrass would be the most prone to injury in such a scenario, especially in low spots and poorly drained areas.
Another source of anxiety is widespread ice cover. Rain and wet snow the first week of January was quickly followed by sub-zero cold, leading to ice formation in many locations. Lasting snow fell shortly thereafter, and along with consistent cold helped to preserve the ice. Ice cover at the UMass Joseph Troll Turf Research Center in South Deerfield, for example, has exceeded 65 days and counting. The main mechanism of injury under ice is anoxia and suffocation due to inhibition of gas exchange, with low-mown Poa annua normally being the most susceptible and creeping bentgrass and Kentucky bluegrass often faring much better.
While everyone speculates, winter injury to turf is a complex and variable problem so it is impossible to precisely gauge the extent until the snow recedes and growth begins… and we’re not quite out of the woods yet. A steady warm up is what we’re looking for - spring thawing followed by a cold spell can doom grasses that have come through previously unscathed, especially when moisture is plentiful as it promises to be this spring. Again, Poa annua, perennial ryegrass and plantings from last fall are particularly at risk from late cold; thankfully the latest forecast looks moderate.
If you can’t wait for snow/ice melt, some sampling might provide some insight into the status – cut holes in the ice and check for sulfur or rotten egg odors and/or pull some plugs, pot them up inside, and watch for signs of life. At the very least, it might help with planning ahead. Aside from some snow mold, current observation of the few melted areas in the Pioneer Valley is mostly encouraging. One certainty right now is that a busy spring is on the horizon.
Submitted by: Jason Lanier