UMASS Landscaping Update

Pioneer Valley (Amherst)

General Conditions: 

Cool, cloudy and wet conditions persisted through this past reporting period in the Pioneer Valley, continuing the month-long trend. Rainfall totals from the rare May Nor’easter spanned 1–2” across the tri-counties, with eastern Hampden County receiving the highest amounts. While it hasn’t been the most pleasant month for being outside in the garden, plants are clearly enjoying the conditions. The cool temperatures have prolonged flowering for many trees, shrubs, and perennials. Additionally, this cool and wet start to the growing season is helping to ease the stress of last year’s crippling autumn drought. A gradual increase in temperature is welcome given all the tender new growth.

As bad as many rhododendrons appeared in the beginning of spring, the past few weeks have shown that a significant number made it through the winter relatively unscathed. Old standbys like ‘Nova Zembla’ and ‘English Roseum’ are putting on a good display. White fringetree (Chionanthus virginicus) and yellowwood (Cladrastis kentukea) are also in full display and providing excellent fragrance and color. New growth on a variety of landscape conifers continues to dazzle, with pine candles protruding upwards from last year’s growth.

Mosquito populations have surged since the warmup on Memorial Day, and black flies are still very active. This is a good time to search for nascent hornet and wasp nests before they become well established. All manner of insects are present across the landscape, and crickets have recently joined the evening soundscape.

Pests/Problems:

Given how wet it’s been this month, it was only a matter of time before one of the major anthracnose pathogens revealed itself. Oak anthracnose (Apiognomonia errabunda) is locally abundant on both young and mature oaks. This native pathogen attacks members of the red and white oak groups, although the disease can be more serious on white oaks. The same fungus also attacks American beech (Fagus grandifolia), and beech anthracnose has been observed throughout the forest. Of course, there is a reduced volume of foliage to infect, as beech leaf disease continues to cause serious decline of beech population throughout the Commonwealth. Surprisingly, and noted previously, sycamores (Platanus occidentalis) look great across Hampshire County despite the wet weather. It’s a prime example of how difficult it can be to predict anthracnose outbreaks and that the fungi responsible are not a monolithic group. Twig and branch cankering fungi are very active right now, and it’s always the right time to prune blighted shoots and stems from the canopy to avoid their buildup and spread. Spider mite injury on hemlock and arborvitae has been observed. 

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

Berkshire Region (West Stockbridge)