A gall, tumor, or burl is an abnormal growth on the leaves, stems, roots, buds, twigs, or crown of a plant. In most cases, the gall is unsightly but not damaging. In small plants, the vascular flow of water and food can be restricted, causing poor growth and making the plant more susceptible to other stresses. A large tree can be weakened by an infection over many years. Nematodes, mites, and insects cause 95 percent of galls. Bacteria and fungi cause the remaining five percent. In most cases, the gall-making organism can be identified by observing the structure of the gall and the species of the host plant.
Galls on Rudbeckia laciniata ‘Herbstsonne’
Fungal galls are spread by ascospores in wind and water and can be found on many common trees including oak, maple, and common privet. Black knot affects many species of the genus Prunus—particularly cherries and plums.
Crown gall is a common problem caused by bacteria. The disease is spread by infested soil, transplants, or contaminated tools. The bacteria enters the plant through wounds caused by cultivation, pruning, or insects. Easy prevention methods are to plant only healthy stock (no suspicious bumps), to clean pruners between use on each plant with alcohol or a 10 percent bleach/water solution, and to take care not to injure plant stems. The bacteria stays active in the soil even after removal of infected plants, so place new, healthy stock elsewhere. Remove and destroy all infected plants. Galls caused by bacterial and fungus are more prevalent during wet years.
A gall can form in response to toxins injected during insect feeding or egg laying, or around a feeding larva. The hackberry leaf gall is caused by psyllids, which are tiny winged insects. Galls formed by insects usually do not affect the overall health of the tree unless they experience early defoliation over the course of many years. Parasites are an important control of this pest. Many oak galls are caused by gall flies and generally are not detrimental. A severe twig infection can, however, cause severe injury and even death. Spruce galls are often caused by several species of an aphid-like insect. If only a few galls are present, they can be cut off and destroyed before the insects emerge in midsummer.
Leaf galls on maple trees form because of feeding mites. Eriophyid mites produce a gall that resembles a felt patch and may occur on the upper or lower side of the leaf. The overall health of the tree should not be seriously affected.
Nematode feeding activity can injure roots and allow gall-forming bacteria into the plant. Nematodes can also form galls on carrots, camellia, fig, gardenia, okra, potato, roses, sweet potato, and tomato. Plants can be stunted, yellow, and wilted due to restrictions on the uptake of water and nutrients. Individual nematodes are invisible to the naked eye, but egg masses can be seen as pearly objects. Roots can appear scabby, pimpled, rough, and have knots. Two important prevention methods are to rotate with nematode-resistant crops and to maintain rich organic soil.
Please contact Plant Information Service at (847) 835-0972 or at plantinfo@chicagobotanic.org for additional information.
We dreamed green, from the moment we started planning the Learning Center on the Regenstein Learning Campus—in every solar panel we placed, in every window we installed, in every cleaning product we used. Recently, the hard work brought us national recognition.
The Chicago Botanic Garden is pleased that the U.S. Green Building Council has awarded the top rating of Platinum LEED (Leadership in Energy and Environmental Design) to the Learning Center, which opened in September 2016. The designation means that the Garden is recognized as a leader in the green building movement. Of 51,875 projects in the United States that has earned LEED status since 2004, only 10.7 percent have been awarded platinum recognition.
Natural daylight from clerestory windows illuminates the Learning Center’s main hallway.
Sustainability Features
People of all ages and abilities connect with the natural world in the programs, classes, and events through the Joseph Regenstein, Jr. School of the Chicago Botanic Garden, based at the Learning Center. In every single decision we made before opening the Center’s doors, we applied the same sustainability standards that we use for our gardens: How do we save water and energy? What is the best way to reduce our environmental footprint?
Solar panels (like these on the Grunsfeld Children’s Growing Garden next door) supply 16 percent of the Learning Center’s electricity.
Here are some of the ways we did so, with the help of architects Booth Hansen & Associates and the Rocky Mountain Institute, which provided sustainability counsel. The Learning Center uses the following:
A rainwater capture and storage system (the rainwater is used to water the Grunsfeld Children’s Growing Garden)
83 solar panels, which generate 16 percent of the building’s electricity
Environmentally friendly cleaning products, and paints, adhesives, and sealings with low amounts of chemicals that could harm indoor air quality
90 percent natural daylight
Special windows to deter bird collisions
Even outside the Learning Center, we made sure to think local and sustainable in the Nature Play Garden, with climbing boulders from Wisconsin and as many native plants as possible—not as part of the LEED certification, but as part of our environmental ethos.
“We are an organization that cares deeply about conservation and sustainability. When it comes to our buildings, we embrace energy-efficient construction practices that mitigate environmental impact,” said Jean M. Franczyk, the Garden’s president and CEO.
Update 4/13/2017: The University of Illinois Extension Program has created a fact sheet for identification of boxwood blight. Download the factsheet here.
Late last year, a colleague asked me to have a look at a boxwood planting at a residence in Winnetka. He indicated that it was looking poor and dropping some leaves. I have seen boxwood with various problems, so I was already guessing what it could be.
Upon arrival, I noted bare sections that had dropped leaves, but also noted strange black streaks on the stems. I ran a moisture chamber test that revealed pink-colored mycelial growth on the leaves, an indication of Volutella blight (a common disease on boxwood that I have seen many times before). More alarmingly, I saw white mycelial growth on the stems that could be signs of boxwood blight—a serious disease of boxwood that has never been found in Illinois. With this in mind, I expressed a sample to the University of Illinois Plant Clinic for diagnosis. About two weeks later, I received a call from the Illinois Department of Agriculture (IDOA) regarding the sample, and yes…it was positive for boxwood blight.
Boxwood blight photo by Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org
Since then, boxwood blight has been found in two other locations in Illinois. All have been traced to nursery stock that came from a source that was not in Illinois; this is good. The IDOA is hopeful that these are isolated incidents that can be contained. Later this month, the IDOA will likely issue a “nuisance declaration” for boxwood blight; this will allow them the authority to mandate proper removal of infected boxwood in an effort to stop any spread.
Boxwood blight photo by David L. Clement, University of Maryland, Bugwood.org
Boxwood blight photo by Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org
Boxwood blight was first discovered in the United States in 2011. Currently, it has been identified in 18 states, primarily in the east. It is being managed at a state level, with various states having different regulations. Some states require nurseries to practice boxwood blight cleanliness programs to ensure the plants they sell are disease free. Here at the Chicago Botanic Garden, we are developing protocol to monitor incoming plants and to monitor our existing collection.
Now that boxwood blight has been found in Illinois, and because boxwood is such a common landscape planting, I feel we should all have a good understanding of this new pathogen. There is no need to panic, but if you have boxwoods, you should monitor them this growing season. I will briefly review boxwood blight for you, but you can find many great fact sheets online by searching for “boxwood blight.” One fact sheet that I found very comprehensive was titled, “Best Management Practices for Boxwood Blight,” from the Virginia Cooperative Extension. Also, the Garden’s Plant Information Service can help you with questions about boxwood blight, but we ask that you do not bring in samples. Call (847) 835-0972, or email plantinfo@chicagobotanic.org.
Boxwood blight photo by Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org
Boxwood blight (Calonectria pseudonaviculata) is a serious fungal disease that primarily affects boxwood (Buxus spp.), but can also hit Japanese pachysandra (Pachysandra terminalis), and sweetbox (Sarcococca spp.). Boxwood blight causes leaf spots, stem cankers, and defoliation. The pathogen itself does not kill the plant, but weakens it to a poor state of health, allowing secondary pathogens to kill the plant. The primary means of spread is by movement of contaminated plants, but it can also be spread via pruning tools, clothing, equipment, and contaminated soil/organic matter. The pathogen can survive in soil and organic matter for years and is easily disseminated by water movement.
Management suggestions:
Monitor your boxwood (at least one a month). Look for the following:
Leaf spots—light or dark brown circular lesions, often with a yellow halo.
Stem cankers—dark brown to black cankers on the stem, diamond shaped or as vertical streaks.
Defoliation—sections of the plant dropping leaves.
If you feel you have found boxwood blight, you should contact the IDA or send a sample to the University of Illinois Plant Clinic for diagnosis. Please do not bring suspect samples to the Garden.
Inspect purchased plants carefully before bringing them home.
Home care:
Plant in locations with good air circulation.
Prune to increase air circulation.
Sanitize pruning equipment before going from one plant to another. Lysol disinfectant works well.
Water at a time of day that the plants will dry quickly.
Avoid overhead watering if possible.
If desired for a hedge or mass planting, it is best to plant loosely and allow them to grow into each other; do not plant tightly.
If we learn of anything new with boxwood blight in Illinois, we will do a follow-up blog. For now don’t panic; just monitor, monitor, monitor.
The Garden is a member of the Sentinel Plant Network, a group that unites botanic gardens in monitoring and providing education on exotic plant pests and pathogens, and works in partnership with the National Plant Diagnostic Network (NPDN).
If you are a plant and bug person like me, please consider becoming a NPDN First Detector and help be on the lookout for these exotic plant pests and pathogens. The NPDN offers an online training course to become a First Detector at firstdetector.org. It’s free, and upon completion, you even get a printable certificate!
No matter where I teach—at the Chicago Botanic Garden or at Edison Elementary in Morton Grove—I see how kids recognize the value of science education.
For each of the last 18 summers, I have been a science teacher at the Garden. My own children grew up attending Camp CBG. It was—and is—a family tradition, and something my kids and I looked forward to each summer.
Teaching Camp CBG is something I look forward to every summer.
The Garden is an extraordinary science location. At the center of its mission are three core “beliefs.” All are excellent, but one correlates most strongly with my values as a science educator: “The future of life on Earth depends on how well we understand, value, and protect plants, other wildlife, and the natural habitats that sustain our world.” For kids, taking care of the Earth is a no-brainer, it is something we should all be doing, a “given.” It has been a privilege to be a part of the Garden’s mission.
In 2014, camp director Amy Wells nominated me for the most prestigious award a science or math teacher in our nation can receive: the Presidential Award for Excellence in Mathematics and Science Teaching (PAEMST). I had the good fortune of being nominated before and achieved recognition as a state level finalist on three previous occasions (2006, 2008 and 2010). As it turned out, Amy’s nomination was the lucky one. Thanks, Amy! After being chosen as a 2014 state level finalist, I was awarded national recognition from the White House in 2015, and got to attend a special ceremony in Washington D.C. this past September with my wife, Tiffany.
My twelve-year journey, from my initial nomination to my national award recognition, intertwines with my teaching at the Garden. Although it was challenging to wait 12 years to finally achieve this recognition, I came to realize it was a journey that forced me to grow as an educator. It made me a better teacher, no doubt, and the hands-on experiences at the Garden honed my skill set—benefitting my school kids and my campers at Camp CBG. Win, win, and win for all.
Posing with my certificate between John P. Holdren, assistant to the President for Science and Technology and White House Office of Science and Technology Policy Director, and Dr. Joan Ferrini-Mundy, assistant director, Directorate for Education and Human Resources, National Science Foundation.
The award ceremony in Washington was magnificent. To be evaluated by experts at that level and recognized by the White House was truly humbling. I was able to meet teachers from around the country who also shared a passion for science instruction. So much positive energy. While I was in Washington, and in the past few months since I discovered I won (while I was working with teachers in Kenya), I have reflected on my teaching history. I recognized that the Garden was such an important part of the teacher I have become. I’ve had the good fortune of teaching hundreds of kids here, in all age ranges, in an environment that maximizes science instruction. Here’s to another 18 years.
—Dr. Jim O’Malley
I got in a quick photo underneath the presidential seal at the entry to the Blue Room during our White House tour.
Fourth grade science teacher Dr. Jim O’Malley, better known as Dr. O to students, has spent the better part of his career engaging kids by offering a mostly hands-on science curriculum where students learn by doing at Edison Elementary School in District 69.
He was a winner well before being honored with the prestigious Presidential Award for Excellence in Mathematics and Science Teaching by helping students tap into their sense of wonder and curiosity as part of every-day science discovery.
What’s black and white and spread all over? Zebra mussels—but they’re no joke.
If you noticed more aquatic “weeds” and algae growing in the Garden Lakes this year—or that our beloved Smith Fountain was MIA after mid-summer—read on to find out why.
Invasive plants and the problems they pose have been the topic of frequent postings here on the Chicago Botanic Garden’s blog. Now we have another invasive species to tell you about—and this time, it’s an animal: zebra mussels.
Adult zebra mussels (Dreissena polymorpha) are about the size of your thumbnail.
Like many invasive plants and animals, zebra mussels’ native range is a faraway place; in this case, eastern Europe and western Russia. In the past 200 years, they have spread throughout all of Europe and Asia. Here in North America, the first account of an established population was in 1988 in Lake St. Clair (located between Lakes Huron and Erie), likely arriving here as tiny hitchhikers in the ballast water of a single commercial cargo ship traveling from the north shore of the Black Sea.
Somewhat remarkably, over the next two years they had spread throughout the entire Great Lakes. Just a year later in 1991, zebra mussels had escaped the Great Lakes and begun their march across North America’s inland waters. (Watch an animation of their spread). Today they are found in at least 29 states.
A zebra mussel may live up to five years and produce up to one million eggs each year—that’s five million eggs over their lifetime. A freshwater species of mollusk, they prefer to live in lakes and rivers with relatively warm, calcium-rich water (to help support their shell development). They feed by filtering microscopic algae from the surrounding water, with each adult zebra mussel filtering up to one liter of water per day.
Though tiny in size (adults are typically ½ to 2 inches long), their ecological and economic impacts can be enormous. Adult zebra mussels prefer to attach to hard surfaces such as submerged rocks, boat hulls, and pier posts—but they also cling to water intake structures as well as the interior of most any pipe that has flowing water in it (such as drinking water supply and irrigation system piping). From an ecological perspective, zebra mussels’ removal of microscopic algae often causes the afflicted waterway to become much more “clear.” While this clearer water may otherwise seem like a good thing, the now-removed microscopic algae is an important food source for many native aquatic animals. The clearer water also allows sunlight to penetrate deeper into the water, thereby stimulating much more rooted aquatic plant growth.
Nearby, zebra mussels were first identified in 2000 at the Skokie Lagoons, just south of the Garden. In 2013 and again in 2014, just a few zebra mussel shells were found at the Garden on the intake screens for our irrigation system’s South Pumphouse. Since so few mussels were found, we were hoping that the Garden’s lakes were simply not a hospitable place for the zebra mussels to flourish. Unfortunately, that thinking all changed in 2015….
These zebra mussels, only a few months old at the time, completely covered this plant label that had inadvertently fallen to the bottom of the Waterfall Garden’s upper pool.
At our Waterfall Garden, 1,000 gallons per minute of lake water are pumped to the top of the garden, after which the water flows down through the garden’s channels and then back into the lake. When Garden staff drained the Waterfall Garden for cleaning in June 2015, there were no apparent zebra mussels present—but by September 2015, the entire bottom of the Waterfall Garden’s upper pool was completely encrusted with attached zebra mussels. Needless to say, we were more than a little alarmed.
Realizing that the Garden’s lakes could indeed support massive growth of zebra mussels, the Garden’s science, horticulture, and maintenance staff quickly came together to devise a remediation strategy that would protect two critical components of the Garden’s infrastructure from “clogging” by zebra mussels: our irrigation system (which utilizes lake water to irrigate nearly all of our outdoor plant collections) and our building cooling systems (three of our public buildings extract lake water to support their air conditioning systems).
Automatic backwash filters like the ones pictured here will be added to each of the Garden’s three pumping stations that withdraw lake water to irrigate nearly all of our outdoor plant collections.
The Garden’s zebra mussel remediation team drew upon the best scientific expertise available in North America, which confirmed that there is no scientifically proven approach for removing all zebra mussels from a body of water. The team explored all potential options for eliminating zebra mussel impacts on our infrastructure, and ultimately settled on two approaches: first, the installation of automatic backwash filters to keep even the tiniest of zebra mussels from getting into our irrigation system (the youngest zebra mussels are about 70 microns in size, or about the width of a human hair), and second, the installation of conventional closed-loop “cooling towers” on the three Garden buildings that currently use lake water for air conditioning (thereby discontinuing all withdrawals of the lake water for building cooling). Final design of the backwash filtration systems and the cooling towers is currently underway, and our intent is to have everything installed and operational by spring 2017.
The Garden’s aquatic plant harvester cuts and removes excessive aquatic vegetation and algae from the Garden lakes.
If you visited the Garden in 2016, you probably witnessed some of the zebra mussels’ ecological impacts to our lakes. Mid-summer lake water transparency in our lakes typically is about 3 to 4 feet—but in 2016, this increased dramatically to about 6 feet (likely due to the zebra mussels’ filtering abilities described earlier). This clearer water resulted in much great submerged aquatic plant growth in our lakes, and our aquatic plant harvester struggled to keep up. Many visitors commented that there was much more aquatic “weed” growth in the lakes this year—and they were correct.
In fact, there was so much aquatic plant growth in our lakes this summer that the water intake for Smith Fountain in the North Lake became clogged and the pump burned out. Look for a repaired Smith Fountain (with a more clog-resistant intake) to reappear next spring.
The Smith Fountain (which is illuminated at night) is an acclaimed feature in the North Lake.
While there currently is no known way to eliminate zebra mussels from freshwater lakes and streams, Garden researchers intend to utilize the new aquatic research facilities in the emerging Kris Jarantoski Campus to explore experimental approaches, such as biological control agents, to potentially lessen the zebra mussels’ ecological impacts to our 60-acre system of lakes. Stay tuned.
