|
Cicada Invasion: What it Means for Maryland Gardeners
Article by Elizabeth Heubeck, Master Gardener Volunteer
 I think most gardeners, myself included, have been anticipating spring even more than usual this year, given the particularly cold and icy winter we endured—not to mention the pandemic, which made it impossible to stave off the winter doldrums with large gatherings of extended family and friends. So it felt like a bit of a gut punch to learn that on top of everything we’ve been fighting this year, we’ll also be battling the once-every-17-year cicada invasion this May that experts say can release more than a million and a half bugs from a single acre of earth.
News of these buzzing, bug-eyed sci-fi looking creatures brings up a lot of questions for gardeners. Most pressing, perhaps, is this one: Will their arrival mean that puttering around the yard, which would have seemed like a safe and peaceful way to ride out the pandemic, will be as off-limits this spring as a full baseball stadium or concert venue? Here are answers to this and other cicada-related questions.
Why are they here now?
This particular breed of cicadas, known as “Brood X”, greets us every 17 years to mate and molt (shed their shell). Scientists suggest that the insects’ 17-year cycle is a clever way to throw off predators, who aren’t likely to share the same one.
Why are they so loud?
What we’ll hear are the male cicadas turning up the volume to attract female cicadas by beating their wings against their abdomen. Apparently, the mating calls can reach 108 decibels—the same level of noise you hear from a car horn just three feet away.
Are cicadas damaging to gardens?
According to the experts, the damage cicadas can cause plants comes from ovipositing—the act of female cicadas cutting small v-shaped slits into tree bark or plant stems to deposit their eggs. If trees and plants are healthy and mature, they can usually withstand the cuts, say horticultural pros, despite temporary withering or wilting to the tips of affected branches. The branches of younger or recently transplanted trees are more vulnerable to the slits made by the female cicadas, and owners may consider draping them in netting to avoid damage.
Are cicadas dangerous to people? No, they won’t bite or sting; nor are they poisonous. They’re generally just a nuisance, due to their loud buzzing noises and large numbers.
How long will they last?
Once they pop out of the ground (only after the soil eight inches below the surface reaches 64 degrees fahrenheit), the cicadas will last between two and four weeks, say experts.
Do cicadas bring with them any benefits?
Yes! The (cicada) nymphs that break through the dirt create a sort of natural aeration by allowing air and water into the ground with the dime-size holes they create. Plus, the carcasses of dead adult cicadas bring nutrients to the soil.
It’s also a once-every-17-year opportunity to get a front-row seat to a rapid-fire succession of natural phenomena. “You can observe every interesting element of biology: birth, death, predation, courtship,” says Michael Raupp, professor of entomology at the University of Maryland.
Sources:
American Association for the Advancement of Science
Brooklyn Botanic Garden blog
Brian Jervis, Ask a Master Gardener, Tulsa World Aug 8, 2017
National Parks Conservation Association
Photo credit: NPR
|
|
Hibiscus, an Honored Plant for 2021
Article by Glen Schulze, Master Gardener Volunteer
 In honor of an eye-catching flowering plant, the National Garden Bureau (NGB) has declared 2021 “The Year of the Hardy Hibiscus”. By “Hardy Hibiscus”, the NGB refers to a perennial hibiscus and its hybrids, that can be traced back to a native North American species, Hibiscus moscheutos. There are several types of Hibiscus, and Hibiscus varieties can be difficult to tell apart. Hibiscus is in the Mallow family (Malvaceae), members of this family have sap that can be combined and whipped with sugar, this was the origin of marshmallows. The Mallow family has more than 200 species, many of which are native to warm tropical areas. The many hybrids (cultivars) sold by nurseries and garden supply companies are intentionally cross-bred to produce eye-catching colors, a variety of sizes, longer blooms and fancy foliage.
Some of the common features of Hibiscus include large, colorful blooms with each flower lasting only 1-2 days and new flowers blooming daily and rapidly. Warm temperatures are needed for Hibiscus to bloom, some species are more tolerant of cold than others. In general, warm, sunny locations are best. An environment providing 4-5 hours of bright direct light will encourage better blooms. Hibiscus can tolerate light shade but can become leggy in those conditions. Hibiscus propagate by reseeding themselves. They can withstand heavy pruning in autumn. Some common diseases of Hibiscus are leafspot and various mildews. Placing the plant in the right environment, cleaning up plant debris and removing infected foliage can help diminish these problems. Pests such as aphids and whiteflies can feast on the plants and Japanese beetles can attack Hibiscus as well. It is possible to manually remove the pests. There is also a hibiscus sawfly, Atomacera decepta, which can quickly defoliate the entire plant. You can read more about this sawfly by following this link: Mallow munchers: Mallow sawfly, Atomacera decepta — Bug of the Week
Mallow family members have nectar which attracts Ruby-throated hummingbirds. In Maryland, you might find beneficial insects around your Hibiscus including butterflies such as Cloudless Sulfurs, and Silvery Blues. Caterpillars of the Common Checkered Skipper and the Painted Lady butterfly will feed on the leaves and the Gray Hairstreak butterfly likes the seeds. Several moth caterpillars also feed on the plants. Hibiscus are cross-pollinated by bumblebees seeking nectar and a specialist pollinator, Ptilothrix bombiformis (Rose Mallow bees) which favor the plant’s nectar and collect pollen.
Let’s take a closer look at a couple Hibiscus that are native to North America, the Hardy Hibiscus and Scarlet Rose Mallow.
Hardy Hibiscus (Hibiscus moschutos) also known as Crimson-eyed Rose Mallow, Eastern Rose Mallow: This Hibiscus is native to marshy areas of the southeast, including our Maryland area. These plants are shrubby perennials 3-8’ tall and 5’ wide. With dull green heart-shaped leaves, they are usually grown in garden landscapes for ornamental value. Their dinner plate size white or pink flowers usually have a darker burgundy center (or “throat”), their blooms are showy. Since it is a native plant of North America, it can survive low temperatures. It is one of the last perennials to emerge in the spring, in fact many times landscape owners give up on the plant and purchase another only to find that later in the spring the original plant has emerged. It can tolerate wet soil conditions, if it is planted in average garden soil, it needs to be provided with sufficient water. For additional information and photos, follow this link: Hibiscus moscheutos (Crimsoneyed Rosemallow, Eastern Rose-mallow, Mallow Rose, Rose Mallow, Swamp Mallow, Swamp Rose, Swamp Rose-mallow, Wild Cotton) | North Carolina Extension Gardener Plant Toolbox (ncsu.edu).
Because Hibiscus moschutos is also known by the common name “Swamp Rose Mallow”, it can be mistaken with Hibiscus grandifloras, which has common names such as Swamp Rose Mallow and Pink Swamp Hibiscus. Hibiscus grandifloras is not native to Maryland. This wetland plant has a pink flower with a darker center the flower opens at night. It is native to the southeast U.S. states such as Georgia and Florida. The learn more about this non-native plant, see the information from: Hibiscus grandiflorus (Large-flowered Hibiscus, Pink Swamp Hibiscus, Swamp Rosemallow, Swamp Rose-mallow, Velvet Hardy Mallow) | North Carolina Extension Gardener Plant Toolbox (ncsu.edu)
Scarlet Rose Mallow (Hibiscus laevis) or synonym Hibiscus militaris also known as Smooth Rose Mallow and Halberd-leaf Rose Mallow: With a height of 4-6’ tall, this Mallow is a deciduous perennial. The common name Halberd-leaf Rose Mallow is from the medieval halberd, a two-handed pole weapon used in the 14th century in parts of Europe. The Halberd had an unusual shape, a mix of a staff and an axe. When Halberd-leaf Rose Mallow’s leaves have 3 lobes, it resembles the halberd weapon. This mallow can also have 5 leaves which resemble a maple leaf. The flower is up to 5” wide with pink to almost white cup-shaped petals and a darker throat. The petals close at night. The plant is related to okra and has slimy sap. Its environment is marshy areas with distribution including Maryland. According to the Maryland Biodiversity Project, it is found only in a few Maryland locations. For additional information and photos, follow this link: Hibiscus laevis (Halberdleaf Hibiscus, Halberdleaf Rosemallow, Halberd-leaved Hibiscus, Halberd-leaved Rose-mallow, Scarlet Rose Mallow, Smooth Rose-mallow) | North Carolina Extension Gardener Plant Toolbox (ncsu.edu)
Next let’s examine a couple of cousins, non-native to Maryland, which have origins from the orient: Tropical Hibiscus and Rose of Sharon.
Tropical Hibiscus (Hibiscus rosa-sinensis) also known as Chinese Hibiscus. Originating primarily from Asian countries, the Tropical Hibiscus is a plant known for its large colorful flowers that can grow to 3-6” and it has glossy deep green leaves. Commonly sold for its ornamental value, the plant’s bell-shaped flowers provide striking colors. It is an evergreen shrub. Because it is intolerant of cold and frost, it can be grown in containers where it will grow to approximately 3’ tall and wide. The container plantings can be overwintered inside. Tropical Hibiscus needs consistent moisture, since it is from a tropical climate, it also needs high humidity. They are sensitive to change in their environment, they dislike drafts, wind, and poor light. Follow this link for more information and some tips on growing and caring for this plant: Hibiscus | UMN Extension
Rose of Sharon (Hibiscus syriacus) also known as Althea shrub: The origins of this plant are China and other Asian areas. It is listed by the Maryland Invasive Species Council (MISC) as an invasive species of concern in Maryland. Since the Rose of Sharon plant has invasive qualities for our state, it’s best to avoid purchasing or planting it. Because it is easily mistaken for the North American native, there are some of the features that help distinguish Rose of Sharon from our native Hibiscus. It has an upright vase shape and flowers which are up to 3” diameter, smaller flowers than our native plants. The flowers are red, white, purple, blue or multicolored and, as with other Hibiscus species, it has a darker central throat. It is a deciduous shrub that is typically taller than our native plants, reaching up to 8-12’ tall with a 6-8’ spread. The leaves are medium-green with 3 lobes and have a palmately-veined structure (resembling the palm of the hand). Unlike Tropical Hibiscus, the Rose of Sharon plant can withstand colder climates. This link will provide more information and photos that can help you further identify this plant: Hibiscus syriacus (Hibiscus, Rose of China, Rose of Sharon, Rose-of-Sharon, Shrub Althea) | North Carolina Extension Gardener Plant Toolbox (ncsu.edu)
As mentioned earlier in this article, Hibiscus can be difficult to tell apart. It is important to be able to know which plant is which in order to avoid planting or potting them in the wrong conditions or accidentally purchasing, planting, or keeping a species that is invasive in our Maryland area. One certain way to make sure which plant you are getting is to specify the plant by its scientific name as well as its common name when purchasing it. The scientific name is noted for each plant discussed in this article. If you discover a Hibiscus plant that is already growing in your landscape, look for some clues mentioned in this article to help identify the plant. You can also request help in identifying an existing plant through the University of Maryland Home & Garden Center at: Ask a Gardening Expert | University of Maryland Extension (umd.edu).
To provide you with additional information about various Hibiscus, some of their cultivars and related plants, please see: Hibiscus | Home & Garden Information Center (clemson.edu)
Hibiscus moscheutos. Photo credit: Larry Allain, U.S. Geological Survey. warcapps.usgs.gov (Public Domain)
|
|
|
|
|
|
