We all know that plants take up nitrogen in significant quantities, compared to some of the other essential nutrients. What most don’t know is that elemental nitrogen (N) is not what is taken up by plants. In fact, nitrogen can be taken up in only two forms, ammonium (NH4) and nitrate (NO3). Fertilizer labels will…Read more about Changing pH and Fertilizing at the Same Time? How nitrogen sources can change soil pH[Read More]
Resources for landscapes and gardens in the Midwest
Landscape Report
Trees, Shrubs, Vines
The Invasive Terrestrial Plant Rule was signed by Governor Holcomb and published on March 18, 2019. The rule goes into effect 30 days after publishing, so it will be effective later in April. The rule states with respect to the 44 plant species included on the rule: “a person must not: (1) Sell, offer or…Read more about Terrestrial Invasive Species Rule Signed by Indiana Governor[Read More]
It is easy to confuse Hemlock (Tsuga spp.) and Yew (Taxus spp.) unless you can see the overall plant habit or have them both side by side. Further confusing them is that both species may be pruned into hedges or other shapes that obscure the natural plant habits. Hemlock has short needles, 1/4 – 3/4″…Read more about Distinguishing Hemlock from Yew[Read More]
Sitting in your back yard on a warm day under the shade of a tree is one of the joys of spring, but there are a growing number of threats that could destroy this experience. Invasive species present dangers like those from above in the form of fragile dead ash trees and from below in…Read more about Emerald Ash Borer University Announcement[Read More]
A look back at the past year may help us be alert to problems ahead. Here’s a summary of the most common problems received in the diagnostic lab on woody ornamentals in 2018. As is typical for most years there were more non-disease (abiotic) problems than infectious (biotic) diseases found on PPDL lab samples in…Read more about Woody Ornamentals Summary 2018[Read More]
The time is now to start protecting your trees! Now that your ears are perked up, let’s talk a bit about Southwest injury on trees. Bark cracking (Fig.1) is a phenomenon that occurs in many species of trees and can have many causes. One of the most common types of bark cracking is termed Southwest…Read more about Preparations to Prevent Southwest Injury[Read More]
The DNR Division of Entomology & Plant Pathology has discovered that a shipment of boxwood plants infected with boxwood blight was shipped to Indiana in May. This is important because boxwood blight (Calonectria pseudonaviculata) is a fungal disease that infests members of the popular Buxaceae family, and is often transported through the nursery trade. Hosts…Read more about Boxwood blight found in Indiana[Read More]
Burning bush is so named for its brilliant red foliage display in autumn. But we sometimes get questions asking why their shrub fails to color up, with leaves that remain green until they drop from the plant. Fall color or lack thereof is affected by a number of factors, including genetics of the plant and…Read more about Alternatives to Burning Bush for Fall Color[Read More]
Bacterial leaf scorch (BLS) on oak is a systemic disease caused by the bacterium Xylella fastidiosa (Xf) (Fig 1). The bacteria live in the xylem vessels (water conducting elements) and restrict water flow. Xf is transmitted from tree to tree by xylem-feeding insects such as leafhoppers and treehoppers. Numerous woody hosts are susceptible to various…Read more about Bacterial Leaf Scorch of Oak: Lab Confirmation Necessary[Read More]
Although most “conifers” are “evergreen”, a few species are “deciduous”. Confused? Perhaps a review of these terms will help. conifer = cone-bearing evergreen = retains at least some green foliage year-round deciduous = all leaves die and are shed annually at same time Evergreens provide green color all year long but that doesn’t mean that…Read more about Even Evergreen Needles Don’t Last Forever[Read More]
Oak wilt has been found in most counties in Indiana and is one of the most serious threats to the health of oak trees in the Midwest, especially those in the red oak / black oak group. The disease is caused by the fungus Ceratocystis fagacearum and is spread from tree to tree by sap…Read more about Oak Wilt in Indiana[Read More]
Boxwoods losing leaves should not be ignored!! Check them carefully for tell-tale symptoms of boxwood blight, a serious fungal disease that causes rapid defoliation and dieback (Fig. 1). The fungus that causes boxwood blight can infect all above ground portions of the shrub. The first symptoms of the disease are dark leaf spots (Fig. 2…Read more about Boxwood Blight – Be on the Look-Out[Read More]
An abiotic stress in plants is a stress due to a non-living factor, such as temperature, moisture, herbicides, etc. Biotic stress includes a living organism, such as a fungi, insect, etc. This series will explore some of the most common types of abiotic stress you may find in landscapes and nurseries. What is wrong…Read more about Common Abiotic Problems of Ornamentals: Soil pH Effects on Fertility[Read More]
Q. We have a large sycamore tree in our yard. Every summer it sheds its bark over a few weeks’ time. I think as it grows it is growing new bark and losing the old bark. Am I correct? – J.C., Walton, Ind. A. You’re on the right track. Peeling bark is normal, and is a key…Read more about Peeling Sycamore Tree Bark is Normal[Read More]
Getting calls from panicked customers about black spots on maple leaves? You’re probably not alone, because now is the time when people start to notice maple tar spot. Every summer we get questions about black spots on maple leaves that look like tar. These spots are not actually “tar” on maple, but are rather a…Read more about Tar Spot on Maple[Read More]
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