UMASS Landscape Update

Pioneer Valley (Amherst)

General Conditions: 

Well, that escalated quickly. After several weeks of cool weather, a warm front brought record-breaking heat and humidity to the Pioneer Valley. High temperatures reached the upper 80s to mid-90s from May 17 - May 20 with dew points creeping into the upper 60s. Heat index values on May 19 approached 100°F. The burst of summer weather was short-lived, however, as more seasonable conditions were forecast to return on May 21. The warmup started on Saturday May 16, and it triggered a mass dispersal of red maple (Acer rubrum) seeds (samaras) and an outburst of mosquitoes. If you enjoy weeding red maple seedlings, the next six weeks will provide ample opportunity.

Accumulations from the scattered showers over May 13 – May 15 were a bit disappointing for the western half of the tri-counties, but the rain was welcome all the same. Totals ranged from 0.6–1.7” in Franklin County, 0.4–1.3” in Hampshire County, and 0.5–1.8” in Hampden County with the highest totals in the east. Rain is forecast, at the time of writing, over Memorial Day weekend, but it’s unlikely that totals will put a dent our long-term rainfall deficit. Soil temperatures have shot upwards with the recent heat but should drop with the cooler weather coming. That said, closely monitor soil moisture for woody plants planted in the last five years and irrigate accordingly. Consider occasional irrigation this summer for larger trees that historically would be left on their own. Lawns are green and vibrant and for untreated and unirrigated turfgrasses, this is the best they’ll look all season.

It’s been a great year for morels (Morchella spp.) in Hampshire County with reports of numerous finds of this seasonal delicacy. At this point, it feels safe to assume the cold nights are behind us, and we won’t experience frost again until the autumn season. Next stop, summer.

Pests/Problems:

As beech (Fagus grandifolia and F. sylvatica) continue to leaf out, we can properly assess the effectiveness of last year’s BLD treatments. There can be considerable variation in success against this destructive disease based on site conditions and other health issues. Woolly beech aphid (Phyllaphis fagi) has been found on the foliage of several European beech. In relation to BLD, this is a trivial pest that does not warrant treatment.

A report of oak anthracnose on red oaks (Quercus rubra) in eastern Hampshire and Hampden County may signal the start of anthracnose season. Dogwood anthracnose symptoms (leaf spots and blotches) are starting to appear on flowering dogwood (Cornus florida) across the UMass campus. Sycamores (Platanus occidentalis) are thin but leafing out, which is a good sign for this time of year. We have been enjoying the honeymoon phase of the growing season when newly emerging foliage is vibrant and healthy. However, that will soon be coming to an end as anthracnose disease symptoms appear along with other pervasive and persistent foliar diseases (e.g. apple scab).

With hemlock (Tsuga canadensis) flushing new growth, we have entered a prime window for treatment against hemlock woolly adelgid (Adelges tsugae) and elongate hemlock scale (Fiorinia externa) using dinotefuran. Keep an eye out for spotted lanternfly (Lycorma delicatula) nymphs, especially when working on sites that have or are near tree-of-heaven (Ailanthus altissima).

Nick Brazee, Plant Pathologist, 

UMass Extension Plant Diagnostic Lab

, reporting from Amherst.