No. 2/May 5, 2020

Modified Growing Degree Days (Base 50⁰ F, March 1 through April 4)
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 below with the degree day accumulations above to determine what insect pests could be active in their area.

Hawthorn Leafminer
Hawthorn leafminer (Profenusa canadensis) are small sawfly larvae that feed between the epidermal layers of the leaf, on the parenchyma cells, leaving small discolored tunnels behind. The areas on the leaf where tunneling has occurred eventually become brown patches. The adults are small black sawflies about 3 mm long. One of the major characteristics used to differentiate sawfly adults from other wasps can be seen when you examine the body where the thorax and abdomen meet. Many wasps have a slender “waist” that connects the thorax and abdomen, but sawflies lack this slender waist and it can be difficult to see where the thorax ends and the abdomen begins.

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 covering called a “scale”. The young crawlers hatch, emerge from the protective scale and become active from May through June. When crawlers choose a location to settle, they pierce the plant with their straw-like mouth parts and suck fluids from the plant and remain in that location throughout adulthood. Fluid feeding can result in leaf yellowing, leaf or twig stunting and, in some cases, plant death. Heavy infestations can also result in die back of the affected twigs and the stress can leave the plant more susceptible to wood-boring insects.

Violets in Landscape Beds
I have a love/hate relationship with violets. In the right setting, they can be attractive and make a nice groundcover. However, they are prolific seed producers and can take over areas. A plant becomes a weed only when it is growing where it is not wanted. I find that I want it in some areas, but not others.

Garlic Mustard
While walking in my neighborhood, I spotted a single blooming garlic mustard reaching for the sun in front of a yew hedge. Knowing there can’t be just one, upon further investigation, I found a larger patch growing the shade behind the yews. Garlic mustard is a weed that must be controlled now, not later. Garlic mustard is an invasive weed that wreaks havoc in our natural areas choking out native plants. The roots of this plant exude a chemical that inhibits the growth of plants around it. This plant can be found in full sun or full shade. Each plant is capable of producing thousands of seeds. Illinois Wildflowers says, “At the present time, Garlic Mustard is the worst herbaceous invader of deciduous woodlands in Illinois as it has the capacity to crowd out and destroy all of the native wildflowers that bloom during the spring.”

Updated Boxwood Blight Best Management Plan Available
By now, we should all be familiar with the various recommendations developed by public health experts to help prevent the spread of COVID-19, influenza, and other diseases. Social distancing, wearing face covers, frequently washing-hands, and regularly cleaning/sanitizing surfaces are practices intended to limit the spread of human pathogens. Experts within green industry compile similar sets of practices with the goal of preventing the introduction, establishment, and spread of plant diseases and other pests. The agreed-upon practices are often referred to as best management practices, or BMPs.

Protecting Pollinators When Using Pesticides
Spring is a time for pollinators like honeybees, native bees, hummingbirds, butterflies and moths to begin to visit our landscape flowers. At the same time, we also have nuisance pests emerging. In order to allow pollinators to continue to do their job and to control pests we should consider a few recommendations to help conserve the beneficials.