Willows (Salix spp.) can be beautiful additions to the landscape. These iconic trees can be found growing naturally in river bottoms, along ponds, rivers, and streams; all areas with consistently moist soil. In the landscape, where soil moisture is much more variable, willows can be stressed by drought, increasing damage from a number of canker[Read More…]
Resources for landscapes and gardens in the Midwest
Landscape Report
Plant Diseases
Slime flux (also known as wet wood) is a dark, foul-smelling and unsightly seepage of sap from tree trunks (fig. 1). The disease is not usually a serious problem but the appearance can be alarming. Slime flux is caused by common surface-inhabiting bacteria or yeast fungi that enter the trunk through wounds associated with improper[Read More…]
Many are familiar with Rhizosphaera needlecast of spruce. If you aren’t, please see these two articles by Janna Beckerman and Megan Haas for more information about the disease and it’s management on spruce. The common name for the disease, needlecast, describes the ultimate fate of the needles: they are cast off. Loss of leaves or[Read More…]
Gray mold (causal agent = Botrytis cinerea) is one of the most common diseases affecting bedding plants. Host commonly include (but are not limited to): begonia, carnation, chrysanthemum, cyclamen, geranium, impatiens, marigold, million bells, petunia, vinca and zinnia. Fortunately, gray mold is one of the easiest diseases to manage. By changing cultural conditions that are[Read More…]
Earthworms are not the only wigglers in the soil beneath your feet. Nematodes, microscopic roundworms, can be found in soil across the globe (even Antarctica!) and are often a barometer of soil and environmental health. However, the nematodes we encounter more frequently feed on plants and cause us, as plant stock producers and consumers, a[Read More…]
Black knot, caused by the fungus Apiosporina morbosa, is a recurring problem on Prunus species. Most Indiana fruit growers, both professional and amateur, have at one time or another observed the black, knot-like warty growths (Fig. 1) that often occur on the woody parts of plum and cherry trees. This fungal disease is one of[Read More…]
Plant pathology is the study of plant diseases. In my career, I’ve studied or witnessed the plant disease epidemics of chestnut blight, Dutch elm disease, sudden oak death, soybean rust, and many more. I am not comparing these to the current pandemic of Covid-19. It doesn’t compare. Please understand this is just an opportunity for[Read More…]
This Nootka falsecypress (Chamaecyparis nootkatensis) is showing severe dieback throughout much of the tree (fig. 1 and 2). The primary pathogen present is a fungus in the genus Diplodia. Small twigs are infected first, which eventually leads to dieback of larger branches (fig. 3). Note the spherical black spore bearing structures (pycnidia) at the base[Read More…]
The dead lower branches in these Austrian pines (Fig. 1) are due to Diplodia (= Sphaeropsis) tip blight. The causal fungus infects newly elongating shoots, in late spring, resulting in stunting and death of the new growth (Fig. 2). Black spore-bearing structures of the causal fungus are formed at the base of the stunted brown[Read More…]
A workhorse of the shade garden, impatiens, also called ‘Busy Lizzies’ delight people by their amazing ability to brighten up shady sites. Downy mildew, caused by the water mold Plasmopara obducens put a damper on things for almost a decade. This downy mildew infects impatiens (Impatiens walleriana), or balsam impatiens (Impatiens basamina). New Guinea impatiens and[Read More…]
The 2019 season provided challenges that were unexpected to the Green Industry, which included an abundance of rainfall followed by drought-like conditions, new invasive pests, concerns about glyphosate use, and many others. The Purdue Landscape Report focuses on timely articles that help Green Industry professionals make decisions for their business and keep abreast of looming[Read More…]
Hunting for mushrooms is a fun past-time, even if you are not looking for edible fungi to “spice” up your cooking. However, when you see a fungal invader popping up in your lawn or landscape, they tend to be unwelcome inhabitants because they are launching sticky spore masses onto your siding, producing foul odors (Figure[Read More…]
If your hostas are looking a little ratty recently you’re not alone (all the photos here are from my garden). Hostas at this time of year tend to have marginal scorch, dieback, leaf spotting and yellowing . A variety of factors may contribute to these symptoms including environment, diseases and insect pests. Anthracnose, caused by[Read More…]
White mold, caused by the fungus Sclerotinia sclerotiorum, is a specific fungal pathogen that infects several hundred species of plants from more than 75 different families, resulting in death of the infected plant (Fig. 1). Many of the most popular annuals and perennial plants have been reported to be susceptible to white mold, from aster (Aster[Read More…]
You are invited to attend this free educational opportunity on campus or via webinar to this event on October 23rd! If you are interested in attending in person, please contact Kyle Daniel at daniel38@purdue.edu for details. Title: The Changing Nursery Industry: How Will You Adapt? Date: Wednesday, October 23, 2:30-5:15 PM, EDT Moderator:[Read More…]
Have you ever noticed the fuzzy growth (Fig1) on the underside of an oak or sycamore leaf and wondered what was wrong with the tree? Fuzzy mats of hairy growth on the underside of tree leaves (Fig 2) are often mistaken for a plant disease or insect problem. In actuality, the whitish-tan fuzzy growth is[Read More…]
Ornamental dogwoods are prone to several leaf spot diseases, but the fungus, Septoria, is commonly found in Indiana. It causes angular, brown lesions bordered by a purplish color on the leaf. The leaf spot symptoms are similar to dogwood anthracnose, however, Septoria does not infect the twigs or branches so it is a much less[Read More…]
Fragrant sumac (Rhus aromatica) is a low growing native shrub that is valued for its adaptability to many soil types, wet or dry conditions, easy care as a ground cover, and for preventing erosion on slopes. It is often found in highway medians (Fig. 1), in parks or as a foundation planting around commercial buildings.[Read More…]
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