No one's gardening crystal ball has been very clear, and there is not a lot we can do except wait and see. Part of the concern comes from gardeners already walking the yard and seeing what's going on outside since it has been so nice. One thing that is a bit different from the typical is that our trees held on to their leaves longer and we did not get them raked up. This has provided more winter protection for our early spring blooming bulbs, and if the leaves are removed now, we are seeing a lot more early spring bloom bulb foliage than expected. Best to cover those bulbs back up. The other concern is with those trees that did not go dormant and kept their leaves late into the fall and early winter. If the buds associated with the leaves were not prepared for the eventual cold weather, then expect some kill, sometimes called bud blast or more troubling will be twig dieback at the very ends of branches. Those trees and shrubs that do not overwinter well anyway are likely to show additional damage.
There has certainly been more insect activity indoors from outdoor insects. Insects and insect-like pests (spiders, for example) are commonly moving around when our temperatures are in the 50s, so you should see them outdoors now or very soon if we continue in our current weather pattern.
Foliage diseases are not as likely to kick in early, as their lifecycles often require prolonged periods of moisture to develop and spread. While they may be problem, they are not expected this early.
Some general gardening activities to do while we have these moderate temperatures is to check for soil moisture on newly planted evergreens and broadleaved evergreens with a limited root system. If there is limited frost or none at all, go ahead and water them. The same goes for other young trees and shrubs planted last year, yet it is not as critical as our evergreens, as they lose moisture all winter long.
If scale insects have been a problem, then dormant oil treatments can be applied, as long the weather remains above freezing for at least a day to allow the oil component to do its job. Last year, a lot of magnolia scale showed up, so do some scouting and treat if needed. Lilac scale and scale on fruit trees in the home orchard are other ones to keep in mind. If those late dropping leaves are so deep there is a concern of actually smothering ground covers, remove a bit of leaves to allow more air circulation to prevent molds and decay. This includes strawberries and similar plants that overwinter as crowns.
And remember, don't panic. Mother Nature always finds a way to come through for us.
Richard Hentschel is a Horticulture Extension Educator with University of Illinois Extension, serving DuPage, Kane and Kendall counties. Stay tuned to more garden and yard updates with "Down the Garden Path" at go.illinois.edu/downthegardenpath and the "Green Side Up" podcast at go.illinois.edu/GreenSideUp