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…]
Resources for landscapes and gardens in the Midwest
Landscape Report
Plant Diseases
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…]
Roses are a popular landscape and garden plant in Indiana. Black spot, caused by the fungus Diplocarpon rosae, is the major foliar disease of roses in Indiana. Infected leaves develop black spots, turn yellow and drop prematurely from the plant. Premature defoliation decreases plant energy reserves and results in reduced flowering of roses as well[Read More…]
Ascochyta blight is a sporadic disease that can infect Kentucky bluegrass, tall fescue and perennial ryegrass. Outbreaks are closely tied to high rainfall or irrigation events in mid to late spring, and drainage patterns. If the lawn is irrigated, Ascochyta can be a sign of too much irrigation. Current rainfall events are providing a prime[Read More…]
To effectively control Taphrina leaf curl fungicides must be applied before bud swell. If you remember seeing red, curled, distorted, leaves on Prunus spp. last year (Figs 1,2) and wondered what might have caused this symptom, the answer is most likely Taphrina leaf curl. Taphrina is a fungal disease that survives in bark and bud[Read More…]
One of the most common diseases found on boxwoods is Volutella blight and dieback, caused by the fungi Pseudonectria foliicola and P. buxi. Both fungi are considered weak pathogens, always around but not causing much damage until plants are injured or stressed, rarely infecting otherwise healthy plants. Volutella blight alone usually doesn’t kill boxwoods, but[Read More…]
Determining the cause of dieback and decline symptoms in landscape trees can be very difficult due to the many cultural, environmental, and biological factors that could be involved. The first place you should look for a culprit when dealing with this type of tree problem is the base of the trunk and the roots. Stem[Read More…]
Galls are gnarly-looking problems for plants and now is the perfect time to be looking for galls on woody ornamentals in the landscape. Without their leaves, these abnormal growths on branches can be easy to spot as you look through the open canopy (Fig 1). There are many different types of galls or gall-like structures[Read More…]
Hair ice, also called ice wool, frost beard, and gnome beard is ice that appears like silky hair (Fig. 1) but forms on dead wood colonized by the fungus Exidiopsis effusa. It is fairly uncommon and not reported in Indiana…but who has been looking for it? Think of the bragging rights! It has been found as[Read More…]
We are in the swing of the holiday season and Christmas decorations, ranging from trees to living wreathes, are for sale at stores. Thinking ahead, you might already have in mind how to dispose of plant material after the holidays, but it is important to take into consideration an important pillar of plant disease management[Read More…]
Northern red oak (Quercus rubra) is a Midwest native and is generally well adapted to growth across much of the region, but we get questions about dieback or ‘flagging’ on it fairly regularly. The two most common causes of twig dieback on this host are Kermes scale (Allokermes galliformis and A. kingii) and fungal canker/dieback[Read More…]
Black root rot (BRR), caused by the fungus Thielaviopsis basicola,has a host range of several hundred plants. In the landscape, the most common hosts include pansies (Fig. 1), and vinca, along with calibrachoa and petunia. In perennial hosts, it often infects lavender, phlox, milkweed and butterfly-weed (Asclepius spp.). Even woody plants, like holly and elderflower[Read More…]
Junipers have to be my favorite group of evergreens, behind a select few pine species. They have a fantastic fragrance, are evergreen, many can tolerate drought, are an ingredient in gin (definitely a bonus), and work well in a variety of landscape uses, including as a barrier plant. They look great year round, except when[Read More…]
Contorted filbert is an ornamental cultivar of European Filbert, (Corylus avellana ‘Contorta’), grown for its twisted, gnarly stems. The plant is also sold under the name Harry Lauder’s Walking Stick. While it’s unique architecture can be impressive, it’s highly susceptible to a fungal canker that can cause extensive damage to the tree. Eastern filbert blight[Read More…]
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