Weather for the middle of June has actually been quite pleasant and mild, mostly dry with humidity rising and a couple of fronts coming through in the last couple of days. Most of the region is experiencing near-drought like conditions with less than an inch of accumulated rainfall, there were localized thunderstorms and showers, but nothing that contributed significant precipitation. Soil temperatures are averaging 71 degrees at 4 inches, which is getting pretty warm and areas exposed to full sun may have dried out a bit. On average 545 growing degree days have been added so far this season. Of course as the growing season continues so do the potential problems, diseases have developed or are presenting in new life cycle stages. Discussed below are several currently being reported as active, this is, by no means, a complete list so make sure to contact your arborist with any questions, concerns or treatment needs.
Anthracnose caused by Aureobasidium on Japanese maple is being reported as active. Leaves appear undersized, distorted and curled. Lesions may first appear along veins at leaf margins.
Oak anthracnose caused by Apiognomonia on white oak has been seen on properties around the region. It is affecting large, mature trees exhibiting undersized, curled, distorted foliage and reduced vigor. Oaks affected with anthracnose may be more susceptible to other diseases such as foliar blights and stem cankers.
The pear leaf blister mite is a microscopic insect pest which feeds underneath bud scales when plant is dormant. During the growing season, mites feed on emerging leaves and fruit during the spring, burrowing under the epidermis, which leads to the development the raised blisters.
Brown needle spot caused by Mycosphaerella dearnessii on eastern white pine is being reported as currently active. Mature trees are experiencing premature needle shedding of last year’s needles. Some needles will appear spotted, while others are necrotic from base to tip.