UMASS Landscaping Update

General Conditions:

The solstice has arrived, marking the official start of summer. This year, a searing heat wave was the final copilot on our annual journey to the longest day of the year. Blazing heat and thick humidity blanketed the Pioneer Valley with heat index values cresting well above 100ºF. With limited rainfall (at the time of writing), the landscape is starting to dry out across the Pioneer Valley. Soil moisture remains good at lower horizons, providing the necessary water for many established trees and shrubs with robust root systems. But for recent transplants and plants in sandy, well-drained soils, supplemental irrigation is necessary now.

As of June 11, only the town of Shelburne has any outdoor water use restrictions in place across the tri-counties. Automatic irrigation systems should be regularly checked to ensure they are operating properly and providing the intended amount of moisture. If hand-watering, check to ensure the root zone is properly wetted. Bark mulch can absorb a significant volume of water, leaving underlying soil dry.

The most recent rainfall on 6/14 failed to deliver significant precipitation for much of the valley. While parts of Hampden and eastern Hampshire counties recorded 2–3” from several scattered showers, the rest of the area was mostly shut out. Even still, the landscape remains green and lush as we round into the final third of June. New growth continues on plants with indeterminate growth rates, like crabapple, red maple. and eastern hemlock. But the honeymoon phase of the growing season is clearly over, and the rigors of the summer are starting to appear.

Pests/Problems:

Weeding and watering is now a primary garden task but also use this time to scout trees and shrubs at a close distance for symptoms of insect infestation and disease.

Both Oriental (Anomala orientalis) and Japanese (Popillia japonica) beetles are beginning to appear in Hampshire County. Powdery mildew fungi are visible on a variety of herbaceous and woody plants. Anthracnose diseases on maple, dogwood and cherry continue to be an issue. However, many of the fungal pathogens responsible for anthracnose have significantly reduced activity during hot and dry periods of mid-summer. Suspected Dutch elm disease flagging has been observed on wild elms and mid to late June is often a time when DED symptoms start to appear on infected trees.

An odd trend that has been reported and observed is the weak flowering on mature kousa dogwoods this year. While only affecting certain trees, several mature kousa dogwoods (Cornus kousa) have either only a limited number of flowers scattered throughout the canopy or isolated patches of dense flowers while the rest of the canopy has none. This weak bloom was not observed on flowering dogwoods (C. florida) earlier this spring.

Many spider mites thrive during extended periods of hot and dry weather. Lacebugs also thrive during dry periods on broadleaved evergreens such as rhododendrons, andromeda, and mountain laurel.