No. 4/May 21, 2018
Modified Growing Degree Days (Base 50°F, March 1 through May 17)
Insect development is temperature dependent. We can use degree days to help predict insect emergence and activity. Home, Yard, and Garden readers can use the links in this article with the degree day accumulations to determine what insect pests could be active in their area.
Oystershell Scale
Oystershell scale (Lepidoasaphes ulmi) can be a tricky species to control without understanding their life cycle and biology. Adults are small, about 2 – 3 millimeters long and can be gray or brown. They can be easily differentiated from other scale insects by the oyster shell shaped scale that covers their bodies. When the females lays eggs, they overwinter beneath her protective scale. The young crawlers hatch, emerge from the protective scale and become active from May through June.
Praying Mantis Egg Cases
Many gardeners may have noticed these foamy hard cases stuck to their shrubs or ornamental grasses. These unusual masses, formally known as ootheca are praying mantis egg cases that will soon deliver hundreds of hungry immatures ready to devour all the bad bugs in the garden. It is startling to see one looking at you as you are working outside but they are a good sign of a healthy ecosystem. Praying Mantis get their name from a Greek word meaning "prophet," "seer" or "diviner." How they stand when they are in position to catch their prey underwrites their name.
Speedwells
These little plants have really escaped my attention over the years. Because they are low growing and their populations seem to be less abundant than their better-known counterparts of henbit and chickweed, they are often overlooked. For some reason, the populations are very high this spring. Perhaps the growing conditions have been perfect for it with the cool temperatures we had for so long. Several types of speedwell also prefer shady conditions.
Rhizosphaera - What It Is, and What It Is Not
Observations of Rhizosphaera needle cast (Rhizosphaera) have been widespread throughout the state for the past several years. As a result, I've been seeing a lot of pictures/videos/articles showing home growers what to look for (and recommending treatment). The issue is, some of those pictures/videos/articles are not actually pictures of Rhizosphaera. They are pictures of a spruce with brown needles, or a video of a spruce with discolored needles, but not likely due to a Rhizosphaera infection.
Black Knot
Black knot is a common fungal disease that affects at least 25 Prunus species, both edible and ornamental. The disease is caused by the fungus Apiosporina morbosa (also known as Dibotryon morbosum), which infects the new twigs, branches, and fruit spurs during the spring. Trunks also can become diseased. Most infections occur between bud break and 2 weeks after bloom when wet conditions are accompanied by temperatures of 55° to 77°F.