Each spring the PPDL receives several samples of oak trees showing curled, twisted, stunted and/or generally ratty looking leaves. When there are holes in the leaves or leaf edges are missing tissue, we add another symptom name to the mix: tatters. Distorted new growth and tatters are most common on white oaks and may occasionally[Read More…]
Resources for landscapes and gardens in the Midwest
Landscape Report
Plant Diseases
Pseudomonas syringae pv. syringae is an opportunistic bacterial pathogen that attacks a diversity of woody ornamental plants. The bacteria cause flower blights, cankers, shoot blights, and diebacks. Symptoms Symptoms often begin as expanding leaf spots. On lilac and viburnum, small spots expand to irregularly shaped brown lesions with yellow halos (Fig. 1). For most other hosts[Read More…]
Rose rosette disease is a severe problem for rose growers and occurs widely throughout many rose growing regions of the US, especially from the mid-South into the Midwest. The problem was described on roses in the early 1940s but actual cause of the disease remained murky until the pathogen was identified as a virus in[Read More…]
There have been a number of samples we have received at the PPDL in recent weeks that bear similar problems worth noting. It is still relatively early for significant in-season disease development due to how cold it has been, although we have certainly had enough rainfall to encourage fungal growth. We have received multiple samples[Read More…]
Two short YouTube videos demonstrate how English and Spanish speakers can use the Purdue Plant Doctor Website. Diagnosing Plant Problems with the Purdue Plant Doctor Web Page (5 minutes -in English with closed captions) Guia Rapida Diagnosticar y Manejar Problemas de las Plantas con Purdue Plant Doctor ( 9 minutes in Spanish with closed[Read More…]
Why Scout? Pathogens, insects, weeds and other pests negatively impact ornamental plant production (greenhouse, nursery, landscape). Integrated pest management (IPM) strategies are used to prevent (ideally) or mitigate damage to ornamental crops. IPM strategies of ornamentals include practices such as proper plant choice for the site, incorporation of resistant varieties when available, the use of[Read More…]
Rust diseases produce some of the most dramatic symptoms and signs we see on woody plants in the landscape. These fungi live up to the name of ‘rust’ diseases because the spore structures they produce on the plant are generally bright orange, as shown by these examples: Cedar-apple rust (https://www.purduelandscapereport.org/article/orange-koosh-galls-on-eastern-red-cedar/), Hollyhock rust (https://www.purduelandscapereport.org/article/jolly-hollyhock-rust/) and Buckthorn[Read More…]
I enjoy gardening and take pride in the variety of flowers my wife and I manage to squeeze into a few beds each Summer. This year an interesting zinnia caught my eye and ended up in our back-yard garden. After fending off rabbits early in the season a new threat emerged in July: bacterial spots[Read More…]
A new disease called Beech leaf disease (BLD), associated with native and ornamental beech trees (Fagus spp.), has been making its way eastward from Lake Erie. First observed in 2012, trees show dark interveinal leaf banding, deformation of the banding tissue, and leaf curling under increased disease severity. Leaves can be stunted and leathery in[Read More…]
Guignardia leaf blotch infects Aesculus species, which include the native plants Ohio buckeye (A. glabra), bottlebrush buckeye (A. parviflora), along with the less common painted buckeye (A. sylvatica) and red (A. pavia) buckeye. The non-native horse-chestnut (A. hippocastanum) is also a susceptible host of this disease (Fig. 1). Symptoms The fungus Guignardia aesculi (pronounced Gwin-yard-ee uh)[Read More…]
All plants can fall victim to insects, diseases, and environmental problems. How they respond to this stress is often the same: Wilting, yellowing, holes, rots, blight—it’s a long list! With so much overlap in symptoms, it can be quite a challenge for people to identify their plant health problems accurately, quickly, and inexpensively. The Purdue[Read More…]
Lilacs (Syringa spp.) are some of my favorite plants alongside Ginkgo (males, at least) and while I could wax poetic about their great aesthetic characteristics I will just say that they have beautiful spring flowers and they smell great, too. However, they do have a handful of problems that cause them to look a little[Read More…]
Brittle cinders and burnt crusts usually bring to mind bad baking experiments, but in this case they are common names for a highly destructive wood rot fungus: Kretzschmaria deusta. The names derive from the charcoal-like fungal fruiting structure (the stroma), where spores are produced (Figure 1). Most wood decay fungi can be classified as[Read More…]
The Problem In recent years, nurseries in multiple states have reported moderate to severe dieback, chlorosis and stunting of redbud (Fig. 1). Dieback is defined as “the gradual but progressive death of individual branches or shoots from tips toward the main stem.” Dieback is a catch-all phrase that describes a constellation of symptoms that include[Read More…]
While recent temperatures have been moderate in many parts of the state, rainfall has been lacking. (See The Annual Drought Article). There are chasms in the clay of my backyard that will swallow my kids and dogs whole. While I am not truly worried about the safety of my smaller family members, a lot of[Read More…]
Join us at the Purdue Turf and Landscape Field Day on July 26th! The Purdue Turf and Landscape Field Day is an annual one-day event with the objective of providing professional turf and landscape managers exposure and educational opportunities with the latest research and technical resources. The Field Day features research tours, talks on current[Read More…]
Arborvitae (Thuja spp.) fulfill several crucial roles in the landscape, especially windbreaks and screens (Fig. 1). Their relatively fast growth habit, wide variety of available forms, and inexpensive price point make them one of the most common conifers in the Midwest landscape. Due to the ubiquitous use of arborvitae, and their perceived problems, the Green[Read More…]
Botrytis blight (also called grey mold) is caused by fungi in the genus Botrytis. The best known of these fungi, Botrytis cinerea, can infect many different hosts, including soft fruit, vegetables, annuals, perennials, shrubs and young tree seedlings (Fig. 1). Other common species of Botrytis are more host specific, including Botrytis elliptica (infecting only lilies[Read More…]
If you have ever seen gooey neon orange branches on trees and shrubs you may have been observing a phenomenon commonly known by the very scientific name of ‘orange goo’. Appearing in cool, wet weather during spring sap flow, the goo is caused by fungi, bacteria and yeast colonizing tree sap, especially where an injury[Read More…]
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