UMASS Landscape Update

Pioneer Valley (Amherst)

General Conditions: 

Spring is roaring ahead in the Pioneer Valley as we begin the month of May. Plants are visibly growing by the day right now and the landscape is blazing with color. Every single year, the transformation from dormancy to green new growth is truly mesmerizing. The tri-counties received a good soaking rainfall on 4/26 with totals ranging from 1–1.7 inches. Surface soils had been drying out a bit with the low humidity and winds but are moist once again. Now that soil temperatures are above 50°F new root growth will significantly increase. The long-term forecast continues to suggest we are safe from spring frost, but cold fronts are moving through the region with regularity, swinging temperatures significantly from day to day.

Pests/Problems:

Beech are leafing out across the region, allowing for assessment of last year’s treatments to control beech leaf disease. Primary symptoms of BLD include dark, interveinal leaf banding, undersized and distorted leaves, unnatural thickening of the leaf tissue and a total blight of the buds. 

Continue to scout for bagworm cocoons and prune to remove, especially from arborvitae. 

The rain on 4/26 allowed cedar-apple rust galls and cedar-quince rust cankers to produce their gelatinous, orange-colored spore masses on infected Juniperus. These spores will disperse to infect susceptible rosaceous trees and shrubs, such as apple, crabapple, serviceberry and hawthorn. According to the UMass Fruit Team, the rain also facilitated spore dispersal by the apple scab pathogen, Venturia inaequalis. As apples and pears enter bloom, fire blight infections may be developing soon depending on conditions. 

Continue to assess rhododendrons, azaleas, inkberries, American and Japanese hollies that suffered from winter injury for signs of new growth. It should be very clear at this point what twigs and branches on rhododendrons and azaleas are dead. However, inkberries and Japanese hollies are sometimes late to push new growth so more time may be necessary for these plants. Dwarf Alberta spruce that suffered winter injury may also be harboring other insect pests (e.g. spruce bud scale and spruce spider mite) along with the needlecast pathogen Rhizosphaera.

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