UMASS Update

Pioneer Valley (Amherst)

General Conditions: 

The fall season has started, the days are noticeably shorter, and students are back on the UMass campus. Meteorological summer ended with an idyllic stretch of weather with high temperatures in the middle to upper 70s and lows dropping into the upper 40s and 50s. After a hot, muggy, and sometimes smoky, summer, the past two weeks have been prime for working outside in the landscape.

But because every rose has its thorn, the lack of rainfall over the past month has caused serious concern. The last significant rain for the tri-counties occurred on August 20 when more than 1” accumulated in many locations. Since then, despite a few passing showers, most weather stations have not recorded any new rainfall. As a result, August precipitation totals were below average throughout the region, ranging from 0.6” to 2.3” from only two rain events.

Soils are dry across sun and shade settings, but the decreased temperatures and waning sun angle has dramatically reduced transpirational water loss. The US Drought Monitor shows intensifying drought conditions across northern Mass, which will only worsen as the compounding effects of drought stress continue. The long-term forecast predicts rain, but totals appear modest at best. Irrigation is key right now as we enter the late stages of the growing season. Plants suffering drought stress are more likely to suffer from winter injury and the previous winter provided ample evidence to support this point. Continue to provide a thorough soaking of the root zone for recently transplanted trees and shrubs. Yet keep in mind that woody plants do not require daily watering and are better served with deeper irrigation on longer intervals.

Early fall color is developing on sugar maples (Acer saccharum) due to drought stress. Other woody plants are developing red foliage (viburnums in particular) as a means of protecting against sunburn as chlorophyll production slows.

Pests/Problems:

The spotted lanternfly (Lycorma delicatula) continues to spread throughout Hampden and eastern Hampshire Counties. See the current distribution map. This invasive insect prefers tree-of-heaven (Ailanthus altissima) and grape (Vitis spp.) but has a wide host range among deciduous hardwoods. The egg masses are well camouflaged and appear as small and flattened masses of mud or putty. They are laid on almost any smooth and flat surface such as stone, tree trunks, buildings and outdoor structures, among many more. Careful scouting should take place for overwintering egg masses so they can be destroyed.

Beech leaf disease (Litylenchus crenatae ssp. mccannii) continues its assault of both American (Fagus grandifolia) and European (F. sylvatica) beech. Late summer and early autumn are when many nematodes migrate to the buds that will produce next year’s growth. While nematicide treatments of beech in landscape settings are providing good control in some cases, forest trees are in major decline across much of the Commonwealth.

Mosquito populations have dramatically declined since their peak in June, due in large part to the dry conditions. 

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