Cool, cloudy weather with frequent rainfall and high humidity provides ideal conditions for the development of several diseases, including downy mildew. The fungus-like pathogens that cause downy mildew are commonly known as ‘water molds’ and are classified as oomycetes. Many types of plants are susceptible to downy mildew diseases, including sunflowers, grapevines, impatiens, other ornamentals,[Read More…]
Resources for landscapes and gardens in the Midwest
Landscape Report
Plant Diseases
During a nursery inspection in Owen County in 2024, I noticed an unusual yellowing of the leaves on some American Hornbeam (Carpinus caroliniana) trees (Fig 1). A look at the underside of the leaves revealed yellow-orange pustules, suggesting a rust fungus. After help from the Purdue Plant & Pest Diagnostic Lab, this fungal pathogen was[Read More…]
Hypoxylon canker is a common disease of mature hardwood trees both in landscapes and in natural wooded areas. The disease, caused by the wood decay fungus Biscogniauxia (formerly Hypoxylon), is most frequently observed in oak tree species, but can also cause dieback in pecan, hickory, golden rain tree, sycamore, maple, beech, birch, elm, willow, basswood,[Read More…]
Excessive and in some cases, abusive rainfall amounts; keys to soggy turfgrass management; winter injury potential causes and recovery, red thread, spring golf disease prevention Weather Spring, which officially started on March 20, is rolling along, and into mid-April temperatures in the region are ahead of statistical normal, but lagging somewhat behind last year. I[Read More…]
Plants that show little growth, are stunted, or are wilted and in active decline are all hallmarks of root stress. Some of the more prominent pathogens that cause root rot include Fusarium, Phytophthora, Pythium, and Rhizoctonia, but there is another fungus which can cause just as much damage in the right situation that does not[Read More…]
Some of you may recall news in 2020 about unsolicited seeds being sent in the mail from overseas (https://www.purdue.edu/newsroom/archive/releases/2020/Q3/unsolicited-seeds-could-wreak-havoc-on-agriculture,-environment,-state-officials-warn.html). There have now been recent reports of this happening again. Ric Bessin, Entomology Extension Specialist, and Joe Collins, Deputy State Entomologist, from the University of Kentucky, wrote about reports of unsolicited seeds from the south,[Read More…]
These oak trees are showing the symptoms of smooth patch (Figures 1, 2, 3). This condition is the result of a fungal infection that is restricted to the outer bark, causing it to slough off. The bark layer remaining is smoother and lighter in color than uninfected, normal bark. Patches can vary from a few[Read More…]
Dieback and canker diseases caused by Botryosphaeria, Sphaeropsis, Diplodia and other closely related fungal pathogens are exceptionally common on woody landscape plants. This group of diseases are often referred to collectively as Botryosphaeria diseases and this article will follow that convention to discuss them as a group. Examine any mature oak tree long enough and[Read More…]
We have received a few elm tree samples this year with a disease we do not often see, but which is relatively common: black spot of elm. This disease, also called elm anthracnose, is caused by the fungus Stegophora ulmea and can affect most species of elm with American elm varieties being more susceptible. The[Read More…]
Summer 2024 was a stressful season for lawns in Indiana and throughout the region. Temperatures often spiked to uncomfortable levels, particularly towards the end of August, and were accompanied by either sweltering humidity or an abrupt halt to rainfall. Diseases such as brown patch on tall fescue were prevalent and leaf spot/melting out diseases on[Read More…]
Early June, we received a white pine sample at the Purdue University Plant and Pest Diagnostic Lab that showed early season needle loss lower in the tree canopy (Figure 1, 2). The majority of conifers hold onto their needles for multiple years, so loss of needles, even in the fall, can come as a shock[Read More…]
Bill Walton, the legendary basketball player, sports announcer and perhaps the most outspoken and famous Grateful Dead fan, passed away in May leaving behind enough quirky quotes and euphemisms to make Yogi Berra proud. In a now viral clip since his passing, Mr. Walton reflects on teachings from his legendary coach and former Purdue basketball[Read More…]
The past two months have been relatively wet and cool to warm. This prolonged period of overcast conditions, high humidity, and light to moderate rainfall is perfect for some of our foliar disease issues. “April flowers bring May Leaf spots” doesn’t have the right ring to it, but we are seeing quite a bit of[Read More…]
Rocky Mountain juniper, Juniperus scopulorum, has gained some popularity in Midwest landscapes due to cold and drought tolerance, and to the availability of several upright columnar varieties with attractive blue color, including ‘Skyrocket’ and ‘Wichita Blue’. Like many other junipers, J. scopulorum may suffer dieback of small branches and twigs caused by the fungal pathogens[Read More…]
Identifying a plant problem is the first step to improve the health of plants in the landscape. We created a series of short (5 to 7 min) YouTube videos to help you learn or just brush up your plant diagnostic skills. Each video guides you through the diagnostic process in real landscapes, reviews pest biology[Read More…]
Identificar qué problema tiene la planta es el primer paso para mejorar la salud de las plantas en el jardín. Hemos creado una serie de videos cortos (5 a 7 minutos de duración) en YouTube. Esto lo hemos hecho para ayudarlo a aprender o simplemente mejorar sus habilidades de diagnóstico de plantas. Cada video te[Read More…]
Hydrangea L. (family Hydrangeaceae Dumort) is an all-encompassing description of a group of herbaceous and woody flowering plants, composed of more than 80 species native to Asia (including Japan), Indonesia, the Americas. Popular hydrangea species include the bigleaf hydrangea (Hydrangea macrophylla), also known as French hydrangea, panicled (peegee) hydrangea (H. paniculata), oak-leaf hydrangea (H. quercifolia) and mountain hydrangea (H. serrata). Hydrangea[Read More…]
Vascular streak dieback is an emerging issue on woody ornamentals in the nursery industry. We have provided information on this topic as the situation has been unfolding (https://purduelandscapereport.org//article/vascular-streak-dieback-of-redbud-what-plant-pathologists-know-so-far/; https://indianagreenexpo.com/sessions/vascular-streak-dieback-an-emerging-issue-in-nursery-stock/). Researchers and Collaborators working on vascular streak dieback will be presenting up-to-date information during the tHRIve webinar hosted by Horticultural Research Institute on Thursday, April 11,[Read More…]
Inonotus dryadeus is one of the more common wood decay fungi we receive at the diagnostic lab in association with declining trees, specifically oaks. Inonotus is found so frequently on oaks it has the common name oak bracket fungus, but it can cause root rot of a number of other hardwood trees (including maples, sweet[Read More…]
Dead man’s fingers is an apt moniker for a gruesome-looking fungus (Xylaria polymorpha and related species) that produces club-shaped fungal fruiting bodies that appear as fingers growing around the base of dying or dead woody plants and even wooden objects in soil (Fig. 1). With more than 25 species of Xylaria, generalizations are difficult to[Read More…]
Sign-up to receive email news and alerts from Purdue Landscape Working Group:
