UMASS Landscaping update

Pioneer Valley (Amherst)

General Conditions:

The autumnal equinox is almost upon us, and we’ve been locked into an extended pattern of warm and sunny days with cool nights, making for some superb early fall conditions. One major downside, however, is the lack of precipitation. Since the last soaking rainfall on 8/18–19, there’s been only one rain event on 9/7, and accumulations were nothing to write home about (0.2–0.6”). Upper surface soils are really drying out, especially in full sun settings. It’s been a long time since we’ve had to properly irrigate here in the tri-counties. Going back to the record-setting rainfall of July 2023, there’s been plentiful and regular rain until this recent dry stretch. Established trees and shrubs should be able withstand this late summer dry spell. From June 1 to August 20, most weather stations in the valley recorded between 14–16” of rain, so there’s still plentiful moisture at lower soil horizons. Newly transplanted trees and shrubs will need a soaking irrigation of the root zone. Hand check the soil following irrigation to ensure the soil is actually wet, as bark mulch can absorb a significant volume of water before it soaks through.

Frogs, spiders, and crickets are still abundant across the landscape as we continue to lose several minutes of light each day. Acorns are dropping and squirrels are busy digging and stashing their hordes. Winterberry and dogwood fruits are quickly reddening. Early fall foliage is developing on scattered trees and the bright sun and cool nights should produce a spectacular display very soon now. The dry weather has helped to suppress mosquito populations.

Pests/Problems:

The beech leaf disease (BLD) nematode (Litylenchus crenatae ssp. mccannii) has been actively migrating to the buds that will produce next year’s growth. While the nematode requires a film of water to move on plant surfaces, they can withstand periods of desiccation until they’re rehydrated. Despite the lack of rain, heavy dew formation during the morning hours likely provides all the moisture they need. The severity of BLD this year across the tri-counties is truly staggering. There were certainly areas of heavy disease present already, but this year saw a rapid expansion of high severity symptoms throughout western Mass. Many of the forests in the western hill towns are dominated by American beech, primarily in the understory where beech thrives as the most shade-tolerant hardwood. The mortality that will ensue over the next several years will transform these forests to a degree not seen since the chestnut blight epidemic. Red maple, sugar maple and red oak will hopefully regenerate in large numbers.

Lilac leaf blotch, caused by the fungal pathogen Pseudocercospora, is once again causing premature defoliation on lilac (Syringa vulgaris). Brown spots, blotches and a complete blight have developed over the past four to six weeks, leaving some plants badly defoliated.