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 a Flower

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.

Galls on a Flower
Galls on a Flower

 

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.


©2017 Chicago Botanic Garden and my.chicagobotanic.org

We love nature here at the Chicago Botanic Garden, so we looked to the natural world for inspiration on how to enjoy the eclipse—here at the Garden, or in your own backyard.

Practice safe viewing at the Garden with eclipse glasses from the Adler Planetarium.

Practice safe viewing at the Garden with eclipse glasses from the Adler Planetarium. Distribution of glasses begins at 10 a.m. Monday, August 21 on the Esplanade.

On Monday, August 21, people across the United States will be able to witness a rare event: the first total solar eclipse to cross over the country from coast to coast in nearly a century.

The path of totality—meaning the area of the United States that will see the sun completely blocked by the moon—passes across southern Illinois. In the Chicago area, we will experience roughly 86 percent coverage around 1:19 p.m. This is the closest the Chicago area has been to a total solar eclipse in 92 years.

 

1. Make a pinhole projector—using leaves.

Rule number one with eclipses—and with the sun every day, actually—is don’t look directly at it with the naked eye. A fun way to indirectly “see” the eclipse is with a pinhole projector, and one of the best natural projectors is a leaf. Leaves often have holes that can act as natural projectors.

During the eclipse, turn your back to the sun and hold the leaf above a neutral colored background, ideally several feet or more away. A white sheet of paper will do. You’ll see a crescent-shaped shadow that changes as the eclipse progresses.

Via Rice Space Institute, a fun way to commemorate an eclipse: make a pinhole sign and photograph its shadow.

Via Rice Space Institute, a fun way to commemorate an eclipse: make a pinhole sign and photograph its shadow.

The easiest pinhole projector you can make is with your hands. Stretch out and overlap your fingers to create a grid. Look down and you’ll see mini eclipses projected through the spaces between your fingers.

Eclipse shadows seen through crossed fingers of kids.

Viewing with children? Use what you’ve got to make your own shadow art: tiny hands are perfect. Photo via blogger Linda Shore

Other ideas: Use everyday objects that already have holes—like colanders or crackers, for example—or by punching a hole in a piece of cardboard or other sturdy material. If you want a more patriotic experience, NASA has 2D/3D printable pinhole projectors in the shape of the United States and each state.


2. Follow the shadows of the trees.

Find a shady spot and watch as the eclipse shadows change over the course of the event. Instead of the one shadow that a standard pinhole projector creates, you can view hundreds by standing under a decently sized oak or maple.

Instead of the shadows of leaves, thousands of sun crescents: the light cast through the gaps in moving leaves is only a sliver of the sun, and it shows.

Instead of the shadows of leaves, thousands of sun crescents: the light cast through the gaps in moving leaves is only a sliver of the sun, and it shows. Photo by David Prasad from Fresno, CA., United States [CC BY-SA 2.0], via Wikimedia Commons, taken during the 2012 annular solar eclipse seen on the west coast of the United States.

Shadows of leaves on the ground during a partial solar eclipse look like a host of small, overlapping crescent moons.

Shadows of leaves on the ground during a partial solar eclipse look like a host of small, overlapping crescent moons. Photo by பரிதிமதி (Own work) [CC BY-SA 3.0], via Wikimedia Commons

Another cool effect created by the eclipse is shadows that look sharper and appear to move (albeit very slowly) as the eclipse goes on. Boyce Tankersley, the Garden’s director of living plant documentation, was in St. Louis during the annular solar eclipse that passed over the United States in 1994, and witnessed this phenomenon while working at the botanical garden there. Unlike the annular 1994 eclipse, where a ring of the sun appears around the edge of the moon, the total eclipse this year will completely block the sun’s light in the path of totality (near Carbondale, Illinois, in our region). That’s because during a total eclipse, the distances between the moon, sun, and earth allows the moon to completely cover the sun; during an annular eclipse, it does not.

Rangers in Grand Canyon National Park use eclipse filters on a pair of binoculars during an annular eclipse viewing in 2012.

Rangers in Grand Canyon National Park use pair of filtered binoculars during an annular eclipse viewing in 2012. Note the crisp shadows at near-peak eclipse, as well as the crisp outline of the crescent sun.
[CC BY 2.0], via Wikimedia Commons

At peak viewing time, from roughly 12:45 to 2 p.m., we’ll see a skinny crescent of light peeking out from behind the moon, almost like it’s taking a bite out of the sun. Though it’s only a sliver, it’s still strong enough to mess with the way shadows appear to the naked eye. This will make for some amazing patterns and changing shapes under the Garden’s trees. If you want to experience the eclipse this way, Tankersley recommends heading to the Waterfall Garden, English Oak Meadow, or English Walled Garden. Even the Garden’s parking lots have big, leafy trees that would work. If you prefer seclusion, the west service road, stretching from the Regenstein Learning Campus to the Graham Bulb Garden, has ginkgo, redbud, and buckeye, to name a few trees in that area with interesting leaves. Use the Garden’s plant finder or download our GardenGuide app to seek out a spot to see the eclipse by your favorite kind of tree.


3. Come to the Garden’s Eclipse Event

The Garden has partnered with the Adler Planetarium to host a solar eclipse viewing event. Free special viewing glasses—while supplies last—will be available so visitors can safely view the eclipse directly. We’ll also have Family Drop-In activities related to the eclipse and a scale model of the moon, sun, and earth stretching across the Esplanade, not far from the Visitor Center.

Crescent-shaped shadows of an eclipse seen through a colander.

Colanders, strainers, slotted spoons, and crackers—use household objects for your own eclipse experiments. Photo via Lightscapes blog.

The Esplanade is going to be a hub of activity, but the Garden has a number of other open spaces for great viewing. Grab your eclipse glasses and head to Dixon Prairie, on the south end of the Garden. When you need a break from staring at the sky, you’ll also see blooming blazing star, wild bergamot, prairie dock, and ironweed. If you’re lucky, you may also spot a hummingbird or monarch butterfly. The prairie is right off the section of the North Branch Trail that winds through the eastern part of the Garden, so it’s easily accessible if you bike here from the south.

Not as off the beaten path, but usually a sure bet for some private space, is Evening Island. It’s home to the Theodore C. Butz Memorial Carillon and features different landscapes on five acres. Head to the lawn overlooking the Great Basin for a clear view of the sky, as well as sweeping, photo-ready vistas. If you’re with a small group, gather in the council ring, inspired by the work of famed garden designer Jens Jensen.


If you miss this year’s total solar eclipse you won’t have to wait too long for the next one. There will be another in seven years, with the Chicago area closer to the path of totality and expected to see roughly 93 percent coverage. Practice your skills this year and you’ll be proficient in eclipse observation by 2024.


©2017 Chicago Botanic Garden and my.chicagobotanic.org

Towering palms, bold swaths of color, and tropical plants have transformed the Chicago Botanic Garden into an exotic paradise this year for Brazil in the Garden.

To create the “Brazil effect,” floriculturist Tim Pollak and Andrew Bunting, the Garden’s assistant director and director of plant collections, drew from designs by renowned Brazilian landscape architect Roberto Burle Marx, who was known for his bold, modernist style.

We talked with Pollak and Bunting to learn how you can grow a Brazil-inspired tropical garden.

Aechmea 'Blue Tango'

Aechmea ‘Blue Tango’

1. Find color in foliage

Burle Marx used bold, bright colors such as purple, orange, and green in his gardens. When planting your garden, Pollak recommended choosing foliage plants with various shades of green. Foliage tones are endless: silvers, blues, bronze, and burgundy. Foliage plants can also bring out the colors of flowers, and vice versa. For instance, if your garden’s foliage is silver, blue, and purple, pops of white flowers will enhance the foliage colors. “Remember,” Pollak said, “there are no rules when it comes to color.” Complementary or monochromatic schemes are subject to taste. But gardens can still be attractive without flowers. Instead, think of flowers as icing on the cake.

Codiaeum variegatum var. pictum 'Pie Crust'

The bright, speckled foliage of Codiaeum variegatum var. pictum ‘Pie Crust’ provides a host of contrasting color all in one plant.

2. Use contrasting textures and shapes

Burle Marx was known for using large swaths of contrasting textures and forms in his landscape designs. Get the Burle Marx effect by choosing plants with various surfaces and shapes. For instance, Pollak said to think about the foliage of your plant—is it shiny or muted? Waxy or fuzzy? Is the venation (patterns of veins on the leaf) netted or in parallel lines? Are the shapes of the leaves long and thin, or short and wide? When shopping at your local garden center or nursery, follow Pollak’s trick: Lay your plants next to each other on your cart or on the floor. You’ll see which plants have different styles, which create a lush, biodiverse mood in your garden.

Calathea burlemarmii 'Burle Marx' and Heuchera 'Dark Mystery'

This Burle Marx peacock plant (Calathea burlemarmii ‘Burle Marx’) surrounded by the dark purple leaves of Dark Mystery coral bells (Heuchera ‘Dark Mystery’)

3. Think: thrillers, fillers, and spillers

Pollak and Bunting often advise gardeners to think “thrillers, fillers, and spillers” when planning their garden design. By using a combination of these kinds of plants, you can easily create a varied garden design. Here’s a breakdown of the three types:

  • Thrillers: Tall plants are your “wow factors.” They’re dramatic, and stand out in your garden. Think of these plants as conversation starters. Pollak and Bunting recommend palms (Arecaceae), elephant ears (Colocasia), and cannas (Canna generalis) for Brazil-themed “thrillers.”
  • Fillers: Medium-sized plants fill space in your garden. They can be interesting foliage plants or flowers, or flowers with interesting foliage. Pollak and Bunting recommend Persian shield (Strobilanthes dyerianus) and firecracker plants (Cuphea ignea) for Brazil-themed “fillers.”
  • Spillers: Low plants spill out of a container, or trail along the foot of your garden bed. Pollak and Bunting recommend sweet potato plants (Ipomoea batata) and purple spiderwort (Tradescantia pallida) for Brazil-themed “spillers.”
"Thrillers," "spillers," and "fillers" in the Crescent Garden.

In the Crescent Garden, Bismarck fan palms (Bismarckia nobilis) and canna (Canna × generalis ‘Orange Punch’) create “thrillers.” The spectacular foliage of Grecian urn plant (Quesnalia marmota) and bromeliad Neoregelia ‘Sunkiss’ fill in the planting (“fillers”). Mexican bluebell (Ruellia brittoniana ‘Purple Showers’) and Purple Heart spiderwort (Tradescantia pallida ‘Purple Heart’) create the “spillers” in the grouping.

4. Create repetition for effect

When arriving at the Garden’s Visitor Center, you might imagine you’ve landed in Miami. Rows of swaying coconut palms, towers of bromeliads, and beds of elephant ears greet visitors as they walk through the Garden. The tropical illusion is deliberate: We repeated similar plants in our beds to broaden the Garden’s designs, making small spaces look larger. In your own garden, you can use swaths of similar plants in rows or curving shapes. The result may transport you to the tropics.

Repetition for effect: planting areas with a single plant create an effect of making an area seem larger.

Repetition for effect: planting areas with a single plant create an effect of making an area seem larger. Golden yellow Duranta erecta ‘Aurea’ is planted around a Buccaneer palm (Pseudophoenix sargentii). Dark Neoregelia ‘Royal Burgundy’ is planted at the front of the bed alongside a grouping of fine-textured Stipa tenuissima feather grass. Behind the palm, a grouping of spiky-leafed Naranjilla contrasts with the fuzzy-leaves of Tibouchina grandifolia.

5. Add a touch of tropics

Planting a tropical-themed garden doesn’t require you to use 100 percent tropical plants, said Bunting, but a few plants can have an impact. To create a Brazil-themed garden, do as Burle Marx did: Find plants within your reach. That is, at your local garden center or nursery, find palms or other tropical plants that can be brought inside for the winter. To care for tropical plants, keep in mind they thrive in heat and humidity, and need plenty of moisture. Use supplementary fertilizer to keep them healthy and thriving. And remember, if you want the tropical effect without tropical plants, there are plenty of ways to think creatively by using bold houseplants, annuals, and perennials.

Aechmea 'Yellow Berries'

Vase plant (Aechmea ‘Yellow Berries’) adds a perfect touch of the tropics to your summer displays.

Learn more about the flora and fauna of Brazil in our upcoming conservation talks, held on the following Thursdays from 2 to 3 p.m. in the Linnaeus Room, Regenstein Center.

AUG
10
Birds of Brazil
Doug Stotz, senior conservation ecologist, The Field Museum
AUG
17
A Butterfly Adventure in the Amazon Basin
Doug Taron, chief curator of the Chicago Academy of Sciences, Peggy Notebaert Nature Museum
SEP
28
Plant Diversity and Conservation in Brazil
Pat Herendeen, senior director, Systematics and Evolutionary Biology, Chicago Botanic Garden
OCT
12
Mycological Adventures in Brazil
Greg Mueller, chief scientist and Negaunee Foundation Vice President of Science, Chicago Botanic Garden

Photos by Tia Mitchell Photography
©2017 Chicago Botanic Garden and my.chicagobotanic.org

How to Grow More Amazing Dahlias Than Your Neighbors

A Dahlia Primer: From Planting to Blooming

Guest Blogger —  August 4, 2017 — 1 Comment

Get ready for an explosive burst of color September 9-10 at the annual American Dahlia Society National Show at the Chicago Botanic Garden. More than 2,000 flowers in the dahlia family will be on display in a wide variety of colors, sizes, and forms. 

Dahlias are indigenous to Mexico, where they were grown by the Aztecs, who used the tubers as one of their staple foods. The plants were brought to Spain and eventually spread throughout Europe, as people appreciated the beauty of the flowers themselves. Through hybridization, there now are more than 70,000 varieties of dahlia, about 1,500 of which are popularly grown.

Here are some tips for growing these beautiful plants in the garden. 

Dahlia bouquet from the American Dahlia Society National Show

ILLUSTRATION: dahlia artOn September 9 and 10, the Central States Dahlia Society and the Chicago Botanic Garden present the 51st annual American Dahlia Society National Show. For detailed information on the show and the Central States Dahlia Society, please visit centralstatesdahliasociety.com


Selecting a site

Pick a sunny spot where, optimally, the plants will receive at least six hours of sunlight. Since dahlias do not like to get their “feet” wet, the area should not accumulate water and should drain well. If the soil is clay-like, it should be amended with leaf mulch, compost, or peat moss. Since dahlias should be planted about 18 inches apart, it is easy to determine the number of plants the area will accommodate.

Planting

You can plant your dahlias as soon as the danger of frost has past, and the soil temperature remains above 55 degrees Fahrenheit. In Chicago, this typically means about the middle of May. However, some growers wait until Memorial Day just to be sure. The delay does not seem to appreciably affect when the first blooms appear. You can start with either potted plants or tubers that have been over-wintered from last year’s crop.

If using potted plants that have already developed a root system, place the plants in the ground so that the top of the potting medium is level with the ground. Many growers will add a slow-release fertilizer (e.g., Osmocote) and/or composted manure to the bottom of the hole. Water the plants once they have been put in the ground, and water as needed to keep the soil moist (about one inch per week).

Planted dahlia tuber

Planted dahlia tuber

A new dahlia plant

A new dahlia plant

When starting with tubers, dig a shallow hole (about 6 inches deep), add material as described above, and place the tuber on its side. Loosely cover the tuber—but do not bury it—with soil. Once the tuber has sprouted and the sprout has reached the level of the soil, the hole should be back-filled. The tubers should not be watered until they have sent out a sprout that reaches above ground level. A word of caution: Tuber sprouts can be quite delicate. It is a good idea to use a short, temporary support until the plant becomes established. You can start with tubers planted directly in the soil or start the tubers indoors in pots to get an early start. If starting inside, the tender plants should be “hardened” off prior to planting in the garden.

Since dahlias will often grow to five feet or more in height, they need to be staked. The stake should be placed in the ground as soon as the plant, or tuber, is in place. Put the supporting stake within a couple of inches of the plant and avoid damaging the tuber. Plastic stakes tend to bend and break. Many growers use ¼- to ½-inch rebar that can be bought from big-box stores or building supply centers. Tomato cages also provide good support.

New dahlia plant staked, tied, and identified

New dahlia plant staked, tied, and identified

Depending on the height of the plant, you should loosely tie it to the supporting stake. The final step in the planting process is to write the name of the variety on a plastic tag. The tag should be stuck in the ground or attached to the support system.

Dahlia bed ready for the growing season

Dahlia bed ready for the growing season

The first several weeks

As the plant continues to grow, additional ties will have to be placed at about 12-inch intervals. After the plant produces three or four sets of leaves and is about 18 inches tall, the plant should be “topped.”  This means that the terminal bud, at the top of the main stem, must be removed. This will be done only once. This process forces that plant to develop lateral stems, which results in more flowers. 

A "topped" dahlia with terminal bud removed, and laterals forming

A “topped” dahlia with terminal bud removed, and laterals forming

Water as needed to keep the soil moist. During this early phase, many growers will use a nitrogen fertilizer to promote leaf growth and stimulate the plant’s development.

Once buds appear

Depending on the weather and maturity of the starting stock, after about six to eight weeks the first buds should appear. These will develop in groups of three. Two of these should be removed. This process, called “disbudding,” will result in larger blooms. The first blooms tend to be the largest ones that the plant will produce. Growers who plan to compete in shows will try to time these first blooms so they appear just before the show.

A dahlia plant ready for "disbudding"

A dahlia plant ready for “disbudding”

During this phase, water the plant as needed. Watering should be done at the base of the plant. Water on the leaves may cause disease, and water on the blooms may cause them to become top-heavy and droop, or even break. Fertilizing during this phase should consist of potassium and phosphorus to encourage root and bloom development. Do not “over-feed’ the dahlias. Fertilizing about every three to four weeks is the generally recommended practice.   

If the plant becomes too full, you should remove a lateral stem or two. This process, called “disbranching,” should be done as close to the main stem as is possible. All plant grooming should be done in the early morning.  Ideally, you should sterilize the cutting tool as you move between plants to avoid the possible transfer of any disease for one plant to the next.

During the growing season, be aware of the impact of pests and plant disease. Snails and slugs may attack the newly planted dahlias. Spider mites are the most common pest. If they attack, the leaves will shrivel and yellow spots will appear. Many growers will preventatively spray once the hot weather arrives to avoid these pests, as remediation is difficult.

A garden full of dahlias

The fruits of your labor

Cutting the blooms

It is best to cut the blooms in the morning using a sharp instrument to make a clean cut. The stem can then be slit along its length to increase water absorption. Freshly cut dahlias will last in the house for one week or longer. 

 

By George Koons, Central States Dahlia Society


©2017 Chicago Botanic Garden and my.chicagobotanic.org

How did the Chicago Botanic Garden end up sharing one of the most sought-after strawberry plants in the world with a three-star Michelin restaurant?   

The collaboration and conservation initiative began after Garden horticulturist Lisa Hilgenberg happened to meet Aaron Keefer, the culinary gardener for the renowned French Laundry restaurant in California’s Napa Valley. At a conference in Iowa, their conversation turned to the rare Marshall Strawberry, known for its exceptional flavor. Keefer mentioned that he would love to grow the plant at the French Laundry, where the prepaid lunch tasting menu begins at $310 a person.

What is the Marshall strawberry?

Strawberry plant in fruit and flower

Strawberries flower and fruit at the same time.

The Marshall strawberry has a storied history. In the early twentieth century, it was a widely grown strawberry variety. James Beard, the legendary cook and television personality, once said he thought the Marshall was “the finest eating strawberry in America.” But by the 1950s, the Marshall had largely been replaced by other cultivars because, due to disease and its short shelf life, it became an expensive strawberry to produce. By 2007, the USDA National Clonal Germplasm Repository in Corvallis, Oregon, was one of the few places to even have Marshall strawberry plants. Now, a handful of private growers is trying to bring it back to prominence.

The Garden’s role

Leah Gauthier, an artist from Maine, is one of the only certified distributors for the once critically endangered berry. Through her website, marshallstrawberry.com, Gauthier sells the plants as they become available. Only nine are available for order this year, and once they’re sold out, the next batch won’t be available until 2019.

In 2012, Hilgenberg was given three Marshall plants from Gauthier, who was living in Indiana at the time. Gauthier drove to the Garden to personally deliver the fragile cargo. Hilgenberg got the Marshall plants into the ground right away at the Regenstein Fruit & Vegetable Garden; one was promptly stolen. But by 2013, Hilgenberg was able to propagate 50 of the strawberry plants, thus helping to preserve and conserve this unique strawberry.  

After her chance meeting with the French Laundry’s Keefer in summer 2016, Hilgenberg agreed to send him some Marshall plants. Coincidentally, the same week that Hilgenberg sent the plants to the French Laundry, Aaron Bertelsen, the gardener/chef at Great Dixter House & Gardens in the United Kingdom, was visiting the Garden. When Bertelsen also expressed an interest in the strawberry plants, Hilgenberg shared some with Great Dixter as well.

Hilgenberg said she hasn’t heard of any other public gardens that have shared plants with culinary gardens like those at the French Laundry and Great Dixter. But to her it seemed like a great opportunity to be part of “a conservation effort connecting more people to this plant.”

StrawberriesSee photos of the beautiful fruits and vegetables being grown at the French Laundry, Great Dixter, and the Chicago Botanic Garden by following Aaron Keefer (tfl_culinarygarden), Aaron Bertelsen (aaronbertelsenofficial), and Lisa Hilgenberg (hilgenberg8) on Instagram.


©2017 Chicago Botanic Garden and my.chicagobotanic.org