UMASS Landscaping Update

Pioneer Valley (Amherst)

General Conditions: 

We’re rounding into the last week of May and overall, it’s been a wet and cloudy month in the Pioneer Valley. At the time of writing, a late season nor’easter is forecast to bring more than 1” of new rain to the region, continuing the soggy trend. Cool temperatures have dominated lately as well but the threat of a spring frost appears to be over. Full sun days have been few and far between at times this month. But blazing color and rich new growth continues to develop, and most deciduous tree canopies are really filling in. Conifer shoots and needles continue to elongate and the contrast between the new and older growth is particularly striking. We experienced warm and humid conditions to start this past reporting period with a cold front delivering isolated and powerful thunderstorms on May 17. Tree damage and power outages were reported. Rainfall totals were variable due to the scattered occurrence of the thunderstorms. Parts of eastern Hampden and northern Hampshire Counties had 1–2” of rain while the rest of the tri-counties recorded totals somewhere between 0.25–0.75”. Soils continue to remain moist, but the uppermost surface can dry out quickly this time of year with the persistent winds and intermittent periods of sun. 

As noted last week, red maples (Acer rubrum) are having a mast year. The volume of samaras raining down on 5/16 and 5/17 was truly impressive.

Pests/Problems: 

As both American (Fagus grandifolia) and European beech (F. sylvatica) continue to leaf out, we can better assess the severity of this year’s beech leaf disease (BLD) symptoms. Some beech in the tri-counties (and elsewhere) are still benefiting from isolation but those are relatively few. In Hampshire County, many forest understory American beech that have suffered through several years of intensifying BLD are struggling badly and near death.

Native holly leafminer (Phytomyza ilicicola) mining was observed on winterberry (Ilex verticillata). Symptoms of the oak leaf shothole miner (Japanagromyza viridula) on young black oak (Quercus velutina) saplings were found. Leaf rolling and scattered feeding from unknown insects is common right now. Much of this damage does not warrant any action but plants should be monitored to ensure it does not significantly worsen.

Despite the wet weather, American sycamore (Platanus occidentalis) appears to be leafing out well right now. Large specimen trees on the campuses of Smith College, Amherst College and UMass all appear respectable at a time when they could be practically devoid of foliage.