California Invasive Species Week is June 3-11. This is the perfect time to raise awareness about the impact of invasive plants on our natural ecosystems and the importance of making informed plant choices. Invasive species can have detrimental effects on local flora and fauna, often outcompeting other plants for resources and disrupting local ecosystems.
By selecting plants that are well-suited to your environment and not invasive, you can make a positive contribution to preserving California's diverse landscapes. Many invasive plants can be aesthetically pleasing and low-maintenance, making them a popular choice for gardeners. However, invasive plants can spread rapidly, taking over natural habitats and causing significant environmental damage. Invasive species often have few natural predators, enabling them to grow uncontrollably and outcompete other plants for resources like water, sunlight, and nutrients. This can lead to the loss of biodiversity, reduced habitat quality for wildlife, and increased risk of erosion and wildfires.
Examples of Invasive Plants in California:
1. Periwinkle (Vinca major)-This evergreen groundcover is a popular species because of its beautiful purple blooms. Periwinkleforms dense mats that can smother native plants and alter soil chemistry. Instead of periwinkle, try planting native groundcovers like California lilac (Ceanothus spp.) or hummingbird sage (Salvia spathacea).
2. Fountain grass (Pennisetum setaceum)-This ornamental grass is highly adaptable and has invaded many natural habitats, including grasslands and coastal sage scrub. Instead, opt for native grasses like purple needlegrass (Stipa pulchra) or deergrass (Muhlenbergia rigens) or the smaller version (Muhlenbergia dubia).
3. Pampas grass (Cortaderia selloana)-A tall, clumping grass with feathery blooms that can quickly dominate landscapes and outcompete native species. Consider planting native ornamental grasses such as blue grama grass (Bouteloua gracilis) or switchgrass (Panicum virgatum) as alternatives to pampas grass.
4. Tree of heaven (Ailanthus altissima)-This fast-growing tree can release chemicals that inhibit the growth of other plants and can sprout vigorously from root fragments. Plant California native trees like sycamore (Platanus racemosa) or western redbud (Cercis occidentalis) instead of the invasive tree of heaven.
Celebrate Invasive Species Week!
organization dedicated to protecting California's wildlands from invasive plants through
research, restoration, and education.
•California Native Plant Society (CNPS)-https://www.cnps.org/-CNPS is a non-profit
organization that promotes the understanding and appreciation of California's native plants and
preserves them in their natural habitat.
•PlantRight-https://plantright.org/-PlantRight works with California's nursey industry to keep
invasive plants out of our landscapes and promotes the sale of non-invasive alternatives.
- Author: Janet Hartin
What do ice cream, potato chips, Scotch and Spanish Broom, and Tree of Heaven have in common? While they're all tempting to indulge in, less is more. In fact, plants such as Scotch, Spanish Broom, Tree of Heaven, Pampas Grass, Green Fountain Grass, and dozens of plants are all considered invasive plants in California. Simply put, they should not be planted. There are some great alternative plants that are better choices listed at the end of this blog.
Truth be told, I admit to falling madly in love with the Spanish Broom (Spartium junceum) shrubs adorning Highway 18 on my drive from San Bernardino to Lake Arrowhead in early spring 1984 right after my job interview for my current position. Being a “wet behind the ears” recently hatched graduate student from the Midwest I was truly in awe of their lovely yellow blooms and vowed to plant one if I got the chance to move to California. Fortunately, I found out very soon that, while the plantings were made on purpose, they were a mistake and needed to be removed due to their invasive nature.
While they were ‘recruited' from Europe and had what seemed like a perfect resumé (fast growth, lovely yellow flowers, adaptability to poor infertile soil and disease and insect-resistance), they didn't play well with others, a fatal flaw. In California, they were aggressive and crowded out native plantings. Fires only exacerbated the situation. After the 2003 burns, the Spanish Broom populations exploded, obliterating any remaining natives and taking an even larger area hostage. In summer 2010, the San Bernardino National Forest removed the plants in a costly but necessary $500,000 project under a partnership with the American Recovery and Reinvestment Act. Constant monitoring continues in the San Bernardino Mountains and other areas of the state to prevent its reestablishment which is challenging due to its ability to quickly resprout, seed longevity, and effective dispersal. It has definitely earned its ‘noxious weed' label!
This is just one example of the problems posed by invasive plants. In effect, they grow too well! They outcompete desirable plants in our gardens, lawns, and other urban and natural areas for water, nutrients, and space. They also shade sun-requiring plants. Threatened and endangered plant species and other California native plants are particularly vulnerable to their encroachment. (In most cases, invasive plants are non-native species.) Interestingly, our beloved state flower, the California poppy, is an invasive plant in New Zealand, Hawaii and other locations outside of California.
As urban gardeners, we can all greatly reduce the impact of the encroachment of invasive plants in our urban environments. Please don't plant invasive sane remove plantings on your property to stop their spread. Below are some great resources to learn more about invasive plants and find viable replacements:
California Invasive Plant Council: https://www.cal-ipc.org/
Don't Plant a Pest: https://www.cal-ipc.org/solutions/prevention/landscaping/dpp/
Invasive Plants of Southern California:https://www.cal-ipc.org/solutions/prevention/landscaping/dpp/?region=socal
By Penny Pawl, U. C. Master Gardener of Napa County
I can feel spring in the air, so it is time to think about which unique, beautiful plants I can add to my garden. As I peruse all the new garden and seed catalogs, I need to remember not to choose any invasive plants.
Many plants in American gardens and natural landscapes have come from another country. Over time, they have really made themselves at home. If you plant them, some of these imports will take over and crowd out native plants.
In Napa Valley, volunteers have had to remove Spanish broom from a local park. Spanish broom has bright yellow flowers and can take over a landscape in a few years.
Many plants become invasive because nothing keeps them in check. The wild mustard in Napa Valley is a good example. It is beautiful but an opportunist, and here it has found perfect growing conditions.
My neighbor planted a beautiful grass with small seedpods. In a short time, the grass was coming up all over their yard. Then it moved to mine. It was easy to pull, but when a seed went up their dog's nose, they pulled the grass out.
A fellow Napa County Master Gardener had a beautiful wisteria. I love this plant and admired hers which was growing on both sides of her 100-year-old house. The vine had grown under one side of the house and come up on the other. No wonder it is on the invasive-plant list.
When my husband and I were new home owners, he planted a weeping willow. He sited it many feet from our well and our home, but its roots advanced quickly toward us. It had to go.
Another neighbor had a beautiful stand of giant bamboo in front of the home. It even bloomed one year and looked wonderful. But then it spread under the house's foundation. Bamboo has a life of it' own and is extremely invasive. In Hawaii, it is everywhere but it is not a native.
One of the most invasive plants is the wild oat (Avena fatua L.). I hand weeded an area of my yard overrun by this plant. It took time but I vanquished it. The following year it did not return, but in two years, there it was again.
I also fell in love with Santa Barbara daisy (Erigeron karvinskianus), also known as fleabane. It comes from Mexico and down the coast of South America. I planted a few small plants that very quickly took over the beds. It had to go. There are natives in the same family that are not such thugs.
The California Invasive Plant Council maintains a list of the most invasive plants in California (http://www.cal-ipc.org/ ). Although nurseries still sell them, these plants threaten natives by competing for water and nutrients. These plants include big periwinkle, English ivy, giant reed, iceplant, onion grass, pampas grass, red sesbania, Russian olive and tree of heaven. Scotch broom and French broom have pretty flowers but they cause changes in the soil and shade out natives. And they produce many seeds that birds move around.
Most of these plants were imported in the 1800s for landscape gardens. The plants decided they liked it here and have moved to many areas where they are not wanted.
If you don't know what to plant, pick a California native. Natives have evolved to thrive in our soil and climate without producing rampant growth. Because they are adapted to California, most do not need much water to survive.
- Author: Surendra K. Dara
Spotted lanternfly (Lycorma delicatula) is an invasive planthopper that was first detected in Pennsylvania in September, 2014 (Dara et al., 2015) and believed to have arrived as eggs attached to stone in a shipment of stone from Asia. This pest is native to China and has been reported in some other Asian countries. Since its first occurrence in Berks County in Pennsylvania, it has now spread to 13 counties in the state and was also reported in Delaware and New York in November, 2017 and in Virginia in January, 2018.
Fruit trees (apple, apricot, cherry, peach), ornamental or woody trees (birch, lilac, maple, poplar, tree of heaven), and vines (grape) are among more than 70 species of hosts that are infested by spotted lanternfly. The tree of heaven (Ailanthus altissima) is a favorite of the spotted lanternfly. Several invasive pests such as the brown marmorated stink bug and the Asian citrus psyllid first found in late 90s in Pennsylvania and Florida, respectively, have spread to other states and are now found in California. Considering its current distribution of the spotted lanternfly in Pennsylvania and other states and its potential to spread to other states, this article provides an update on recent efforts to monitor and control this pest.
Biology and damage
Eggs are deposited in masses and covered by a waxy substance. There are four nymphal instars. Female lanternflies are larger than males. Nymphs and adults feed on the phloem and excrete large volumes of liquid. Severe feeding damage results in oozing wounds on the trunk, and wilting and death of affected branches.
Egg masses of the spotted lanternfly. Photo by Lawrence Barringer, Pennsylvania Department of Agriculture.
Fourth instar nymph of the spotted lanternfly. Photo by Lawrence Barringer, Pennsylvania Department of Agriculture.
Adult spotted lanternfly infestations. Photo by Lawrence Barringer, Pennsylvania Department of Agriculture.
White mold developing on the excretions of the spotted lanternfly. Photo by Lawrence Barringer, Pennsylvania Department of Agriculture.
Monitoring and controlling
Preventing the movement: To prevent the spread of the spotted lanternfly, carefully inspect potential sources such as woody plant debris, yard waste, plants, or other objects. Destroy or disinfest the sources as appropriate to prevent the spread of the pest.
Removal of the host: Removing tree of heaven, a favorite host of the spotted lanternfly and an invasive species of tree, can reduce the risk of pest infestation and spread. Reducing the plant stand to 15% is considered a primary strategy for preventing the spread of spotted lanternfly. The tree should be removed with its entire root system when possible. If the tree was cut, its stump should be treated with herbicides to prevent regrowth. Care should be taken while removing the tree of heaven since the toxic plant sap can cause skin irritation, headaches, nausea, and in some cases cardiac problems. Sumac and black walnut trees also look similar to the tree of heaven, but when bruised, the leaves of the latter give out a rancid peanut butter odor.
Sticky bands: The Pennsylvania Department of Agriculture placed 13 counties under quarantine and is currently providing sticky bands for volunteers participating in the monitoring program to place on trees. Sticky bands are placed around the tree trunk about 4' from the ground to trap the nymphs and adults that are moving around. While younger nymphs can be captured on less sticky bands, stickier bands are necessary to capture older nymphs and adult hoppers. Those not participating in the volunteer program can purchase sticky bands or sticky substances from commercial vendors or make their own by wrapping a tape around the trunk and applying petroleum jelly or other materials on the tape. This strategy helps to detect and trap the pest infestations. More than 1.7 million spotted lanternflies were reported to be trapped in 2017 in Pennsylvania using sticky bands.
Spotted lanternfly nymphs and some adults trapped on a sticky band. Photo by Lawrence Barringer, Pennsylvania Department of Agriculture.
Pesticides: Contact insecticides, bifenthrin and carbaryl and systemic insecticides, dinotefuran and imidacloprid appear to be effective in controlling the spotted lanternfly based on the studies conducted in Pennsylvania. Neem oil and insecticidal soap also provide some control. However, pesticide applications appear to be a short-term solution as they cannot prevent reinfestation.
Biocontrol agents:It is thought that toxic metabolites in the body of the spotted lanternfly and its brightly colored hindwings tend to deter general predators from feeding on the pest. However, the predatory wheel bug, Arilus cristatus (Hemiptera: Reduvidae) and stink bug, Apoecilus cynicus were found feeding on adult spotted lanternfles in Pennsylvania (Barringer and Smyers, 2016). Some egg parasitoids were also reported to be attacking the spotted lanternfly in China (Choi et al., 2014) and South Korea (Kim et al., 2011). Liu and Mottern (2017) found Ooencyrtus kuvanae, an egg parasitoid imported for controlling the gypsy moth (Lymantria dispar), attacking the egg masses of the spotted lanternfly in Pennsylvania in 2016. These native predators and introduced parasitoids could be potential biocontrol options for the spotted lanterfly.
Microbial control agents: Entomopathogenic fungi Beauveria bassiana, Isaria fumosorosea, and Metarhizium brunneum may also play a role alone or in combination with azadirachtin for controlling spotted lanternfly and researchers should explore microbial control.
Refer to the earlier article on the pest biology and damage at http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=15861
Spotted lanternfly in Entomology Today: https://entomologytoday.org/2015/12/17/be-prepared-for-spotted-lanternfly/
Barringer, L. E. and E. Smyers. 2016. Predation of the spotted lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae) by two native hemiptera. Entomol. News 126: 71-73. https://doi.org/10.3157/021.126.0109
Choi, M. Y., Z.Q. Yang, X. Y. Wang, Y. L. Tang, and Z. R. Hou. 2014. Parasitism rate of egg parasitoid Anastatus orientalis (Hymenoptera: Eupelmidae) on Lycorma delicatula (Hemiptera: Fulgoridae) in China. Korean J. Appl. Entomol. 53: 135–139.
Dara, S. K., L. Barringer, and S. P. Arthurs. 2015. Lycorma delicatula (Hemiptera: Fulgoridae): A new invasive pest in the United States. J. Integ. Pest Mngmt. 6(1): 20. https://doi.org/10.1093/jipm/pmv021
Kim, I. K., S. H. Koh, J. S. Lee, W. I. Choi, and S. C. Shin. 2011b. Discovery of an egg parasitoid of Lycorma delicatula (Hemiptera: Fulgoridae) an invasive species in South Korea. J. Asia Pac. Entomol. 14: 213–215.
Liu H. and J. Mottern. 2017. An old remedy for a new problem? Identification of Ooencyrtus kuvanae (Hymenoptera: Encyrtidae), and egg parasitoid of Lycorma delicatula (Hemiptera: Fulgoridae) in North America. J. Ins. Sci. 17: 1-6. https://doi.org/10.1093/jisesa/iew114