UMASS Landscape update

Pioneer Valley (Amherst)

General Conditions: 

The dormant season has arrived and the 2025 growing season is complete. Trees and shrubs are acclimating for cold winter temperatures, and fall clean ups continue across the landscape. Peak fall foliage was late this year, but still spectacular in the end. In early October, it seemed this might be an underwhelming year, but the colors came hard and vibrant for many trees. Even Norway maples (Acer platanoides) across the UMass campus have looked great this year with a golden-orange color. Japanese maples (A. palmatum) were especially bright and late, per usual, peaking in late October to early November throughout the valley.

Rainfall was also abundant during this last reporting period of the 2025 season. Over a three-week span (October 20 to November 10) more than 5" was recorded at the Easthampton gauge. Across the Pioneer Valley, totals during this stretch spanned 4.5–7.2” in Franklin County, 3.4–5.3” in Hampshire County, and 3.2–4.6” in Hampden County. With the cool temperatures and low sun angle, soil moisture is abundant and will remain so heading into December. The brunt of this rainfall occurred on October 30 – October 31 when 2–3” was deposited in the tri-counties.

It’s also been very windy recently, and a peak gust of 54 mph was recorded on Halloween at Barnes Airport in Westfield.

As woody plants enter dormancy, avoid any major pruning for shape. Heavy pruning in autumn can disrupt cold acclimation and make trees more susceptible to winter injury. Winter and early spring pruning is preferred for many deciduous hardwoods and conifers.

Pests/Problems:

Most pest and pathogen activity has ceased with cold nights and cool days. Deer, rabbits, and rodents like meadow voles can destroy valuable trees and shrubs during the winter season. Fencing, trunk guards and repellents should be applied or put in place soon to avoid browsing injury over the next several months.

Winter pruning for disease sanitation should focus on dead twigs and small limbs that can harbor cankering fungi in the canopy. Additionally, certain trees require regular pruning to remove suckers and improve air flow and light penetration into the canopy. Crabapple (Malus), plum (Prunus domestica), Japanese maple (A. palmatum) are prime examples of trees that should be regularly pruned for disease control.

The winter season is also a good time to prune overstory branches from trees that are encroaching over landscape beds and casting an increasing amount of shade. Many trees and shrubs that were planted into full sun are slowly draped in shade as the overstory edges creep in over the years. This has a cascading effect on disease development, such as needlecast on spruce and hard pines, for example.

Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from Amherst.Mr. Kenneth Tamsin

CMCA, AMS, PCAM