UMASS Landscaping Update

Pioneer Valley (Amherst)

General Conditions: 

The beauty of the new growing season continues throughout the Pioneer Valley as the month of May fades out and June ushers in the beginning of summer. The tri-counties received a soaking rainfall over Memorial Day weekend. Unfortunate that it had to coincide with the holiday, but the totals made it worthwhile. Nearly every weather station recorded at least 1” of rainfall, with many totals falling in the 1.1–1.4” range. The long duration storm and cool temperatures allowed the rain to soak in well, and the steady winds following were beneficial to dry things out and help reduce foliar disease development.

If you’re in need of reliable rainfall data, NEWA Cornell is a good source with >60 weather stations in Mass. For past totals, go to the box on the bottom right labeled "Weather Tool's", click on "Weather Data Query", and enter the date range on the left.

Presently, fringe tree (Chionanthus virginicus), mariesii viburnum (Viburnum plicatum f. tomentosum 'Mariesii'), and catawba rhodies (Rhododendron catawbiense) are showcasing their amazing floral sets. The lime green growth cascading downward on eastern hemlock (Tsuga canadensis) shows yet again the appeal of this graceful conifer. There are numerous semi-dwarf and dwarf cultivars with exceptional landscape character.

Crickets have joined the nighttime soundscape and with the mating calls of tree frogs and the variety of songbirds foraging and nesting, the landscape is very active. Mosquitoes and black flies are abundant, and the latter will likely hang around for a few more weeks.

There’s been a dip recently in pollen production after oak (Quercus) catkins were shed, but that will quickly change as eastern white pine (Pinus strobus) pollen reaches its peak over the next two weeks.

Keeping the mowing deck set high can improve turfgrass health and allow many low-growing flowering weeds, such as white clover (Trifolium) and ground ivy (Glechoma), to escape the blade if desired.

Pests/Problems:

A clearer sense of how beech leaf disease (BLD) treatments worked (or didn’t) is developing as we enter June. A prominent symptom this spring is marginal leaf distortion on both European and American beech. Continued scouting and recording is still necessary to get a sense of this year’s disease severity.

A large ginkgo (Gingko biloba) on the UMass campus is exhibiting patchy areas of undersized foliage interspersed with leaves of normal size. Smith College reports a similar appearance to their ginkgoes, suggesting the issue may be widespread in the area. It’s possible this is damage from the April 20 freeze event in the valley which has produced distorted and undersized foliage on a range of deciduous trees and shrubs. Temperatures plummeted into the mid-20s that morning after many plants had broken bud or flushed new growth after record warm temperatures the week earlier.

Foliar diseases of deciduous hardwoods, such as anthracnose, are starting to appear across the landscape. Dark, angular-shaped spots and blotches with a collapse of new growth are the most common symptoms. The recent rainfall will have spurred development but presently it appears that anthracnose is locally abundant, and any widespread activity is yet to develop.

Needle blight of pines is on full display for infected trees. Both hard (two- and three-needle) and soft (five-needle) pines are susceptible to a variety of fungal pathogens responsible. Presently, older needles are brown and prematurely shedding from the canopy as the new growth continues to elongate.

Heat scorch from the blazing temperatures from May 17 – May 20 has been observed. For example, newly emerging growth on a young weeping European silver fir (Abies alba ‘Pendula’) were badly burned by the heat.

Nick Brazee, Plant Pathologist, 

UMass Extension Plant Diagnostic Lab

, reporting from Amherst.