UMASS Landscape Update

General Conditions: 

As we settle into late summer in the Pioneer Valley, there’s no doubt it’s been a strong growing season for many trees and shrubs. But an increasing number of plants are starting to look worn and tired from the periods of intense heat and humidity. July wrapped up with another heat wave (July 28 – July 30) with ambient air temperatures in the mid-90s and heat index values >100°F each day.

Two rain events (July 26 and July 31 – August 1) bookended this latest blast of heat and provided some badly needed moisture. The latter event produced 1–2+” at many locations and this soaking rainfall went a long way to restoring many parched landscapes. July rainfall totals across the tri-counties ranged from: 1.2–3.4" (Franklin County), 3.0–5.9" (Hampshire County), and 2.1–5.4" (Hampden County). The first week of August has been dry and mostly sunny with a return of the hazy smoke produced by Canadian wildfires.

Considering that August can be one of the drier months of the year, continue to carefully monitor soil moisture levels. Drip irrigation systems can be useful in staving off drought stress, but they must be regularly checked to ensure they provide the correct volume of water to target plants. Overhead sprinklers should not be wetting the canopy of trees and shrubs as it can promote disease development. While it’s most time consuming, hand watering is preferable in many cases, as the soil can be immediately checked to ensure proper wetting and plants can be simultaneously scouted for health issues.

Many small toads (Anaxyrus americanus) have been recently encountered along with an array of bees, flies, wasps and butterflies. Mosquito populations are considerably lower after the June peak, yet black flies are still abundant, swarming in the morning and evening hours. Cicadas and katydids have joined crickets and grasshoppers in the evening soundscape.

Pests/Problems:

Transplant shock dooms many new plantings in the landscape, making trees and shrubs susceptible to environmental stress, along with opportunistic insects and disease. Late summer to early autumn is an ideal time for transplanting many conifers such as pine (Pinus) and spruce (Picea). With new growth mostly to fully developed, conifers can be safely moved to new sites where they can establish new roots prior to winter dormancy. Transplanting conifers in the spring when they are flushing new shoots and needles can result in serious cases of shock that some trees never recover from.

Maple anthracnose (Discula campestris), oak anthracnose (Apiognomonia errabunda) and black spot of elm (Gnomonia ulmea) are locally abundant this year and causing significant damage in some cases.

Continue to scout and document the occurrence of annual mushrooms and conks of wood-rotting fungi like Laetiporus (chicken of the wood) and Ganoderma (reishi and artist’s conk). Mushrooms produced by Bondarzewia (Berkeley’s polypore) are aging and may appear tan to brown in color as opposed to the cream color they display when fresh.

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