Poison Ivy Patch
Image by Tim Kennelty

Learn about poison ivy and how to treat any reaction to its oils in this podcast episode.

Episode 14: Poison Ivy

Join the podcast co-founders with a lively discussion about the dreaded poison ivy. Learn how to identify it, control it, and treat your symptoms should you be allergic to its oils. Then the focus of Good Plant/Bad Plant with Tim Kennelty is Serviceberry and Invasive Bittersweet . Are your plants looking for a friend?  Deven Russ (Hits and Myths) discusses the realities of companion planting

Photo by: Tim Kennelty

Production Support from:  Linda Aydlett, Teresa Golden, Dorian Hyland, Mary Ann Iaccino, Deven Connely, and Sandra Linnell


Poison Ivy : Poison ivy - Pacific poison oak, Poison sumac, Skin rash (poison-ivy.org) ; Poisonous Plants | NIOSH | CDC

Serviceberry and Invasive Bittersweet (Tim Kennelty with Good Plant/Bad Plant):


Wisconsin Horticulture: Serviceberry, Amelanchier spp; NC State Extension: Amelanchier canadensis; UMN Extension: Serviceberry

Invasive Bittersweet:

https://www.wnyprism.org/invasive_species/oriental-bittersweet/; https://mnfi.anr.msu.edu/invasive-species/OrientalBittersweetBCP.pdf; https://blog-yard-garden-news.extension.umn.edu/2018/11/making-holiday-wreath-avoid-killer-vine.html

Companion Planting (Devon Russ with Hits and Myths):

Horticultural Myths: https://puyallup.wsu.edu/lcs/; Old Wives' Lore for Gardeners, by Maureen & Bridget Boland. Farrar, Srauss & Gioux, 1976; Roses Love Garlic AND Carrots Love Tomatoes, both by Louise Riotte. Garden Way Publishing, 1983 and 1975; https://puyallup.wsu.edu/lcs/

Companion Planting: https://www.gardenmyths.com/tag/marigolds/; Growing vegetable gardens near black walnut trees - MSU Extension ; Japanese beetles: Do four o’clock flowers help? | UMN Extension

Transcript:Welcome to Nature Calls: Conversations from the Hudson Valley. Our team's goal is to present science based information about gardening and all things nature in New York's Hudson Valley. Hosts Jean and Tim, along with team members, Teresa and Linda, are Master Gardener Volunteers for New York's Columbia and Greene counties. So if you're interested in gardening or nature or nuggets of information about what's happening outside your door, settle in, enjoy the conversation. Whatever the season, we have something to say.

Musical segue

Tim: Hi, I'm Tim Kennelty.

Jean: And I'm Jean Thomas.

Tim: And welcome to another episode of Nature Calls: Conversations from the Hudson Valley. Jean, who's our guest today?

Jean: Us. You and I and Linda and Teresa are going to have a roundtable.

Tim: I love it when our guest is us. Yeah, roundtables are the best, aren't they? And this is about something that's really an important topic - poison ivy.

Jean: I call it the national flower of Greene County.

Tim: You know, poison ivy is increasing because of climate change. And I think a lot of people who are buying new homes are just discovering that they have it on their property. So it's really something to know how to identify, and know what to do when you have been exposed to it.

Jean: And it's very clever. It has many disguises.

Tim: It does.I can tell you that I have been to the hospital many times for poison ivy, I'm super, super allergic to it. So I'm sure there are other people out there who are as well, and hopefully this would be really good topic for them.

Jean: And then you're going to talk to us some more about Good Plant / Bad Plant, aren’t you?

Tim: This is the Tim episode, I guess. Yeah. Today I'm going to talk about my good plant is serviceberry or juneberry or shadbush. And they're blooming just about this time of year. It's a really early blooming pollinator shrub; great larval plant for a bunch of different butterflies; great berries for birds. It's a really nice wildlife shrub.

Jean: And if you're a fisherman that tells you when to go looking for the shad in the Hudson River.

Tim: That's right. Absolutely. And the bad plant today is the non-native bittersweet. There's a native bittersweet, but this is the non-native one. People used to use in wreaths. I think I did many, many years ago, and that's one of the ways that got spread.

Jean: Well, it's gorgeous.

Tim: It's a pretty plant. But it is a really, really, not just a noxious weed, but it really can pull down trees and it can take over. I have a lot of it on my property is really, really difficult to manage. So it's good to be able to identify it, and know what it is, and be able to know how to control it.

Jean: And now, if you're even the least bit unsure, drive along Route 787 along the Hudson River in the fall after the first hard frost, and it is terrifying.

Tim: Yeah, it's kind of depressing, isn't it? Yeah. Nice bright color. While a lot of the invasives are depressing, but we're going to talk about how to identify it, if you have a little bit on your property, and how to manage it.

Jean: And then we move along. We're talking about companion planting for good guys getting along together.

Tim: Oh yeah, this is Hits and Myths. Does companion planting really work? It's a real thing. And it's that back to that kind of three sisters - squash, corn and beans. Does it make sense to plant them together? Is there a real scientific basis for that? And do you plant marigolds along your tomatoes to keep the rabbits out and all of those things? Are those real or not? So there's a lot to listen to today. A lot of good, bad and ugly today to listen to right?

Jean: Yep, lots of plant behavior.

Tim: Excellent.

Musical segue

Teresa: Welcome to 'It's Your Call.' We're your hosts, Master Gardener Volunteers, Linda Aydlett, Jean Thomas, Tim Kennelty, and I'm Teresa Golden. Every week the Master Gardeners Help Desk receives a variety of questions about plants and animals, soils and insects. We'll be sharing some of these questions and our answers with a roundtable discussion of the topic.

Linda: So here's our first question from Carol, a gardener in Columbia County. Carol says my husband and I just moved into a new house. We wanted to start planning a garden but are worried about poison ivy. Can you tell us what it looks like, and what we can do about it?

Jean: Okay, we'll give you identification for starters. Sumac family is where the poison ivy, poison oak, poison sumac all live. Its formal name poison ivy is Toxicodendron radicans. It's a woody vine with hairy, aerial roots.

Tim: It's got compound leaves with three leaflets. They can be glossy or dull.

Jean: They're climbing or a strangling vine, and they have inconspicuous flowers.

Tim: And it actually has berry like white fruits with a single seed.

Teresa: But be careful because all parts of the plant contain resin, that if it makes contact with the skin, can cause an unpleasant, itchy rash. Not everyone is susceptible and the effect can vary even in individuals.

Linda: What happens is the resin or oil, urushiol, binds to skin proteins on contact. The human immune system recognizes this, and responds with skin eruptions that can eat and burn. They can develop in 12 hours to up to five days.

Teresa: And it's key to understand that it can adhere to clothing, boots, pet hair, and then transfer to your skin. I once got poison ivy simply doing the laundry, when my husband was outside and brought it in on his jeans. And you can still contract the rash when you have contact in winter. Jean I think you have a story about this.

Jean: I do. When we first moved into our house, we had a tree that needed to be taken out. It was the middle of the winter. My husband's friend came and brought his two kids and the four of them went out and chopped down the tree like regular lumberjacks. And a week later, we heard that the friend was in the hospital because the tree was wrapped in poison ivy. And none of us recognized it in the winter mode, but it was still toxic.

Tim: Yeah, it's really it's really toxic all time severe. I've actually gone to the emergency room for poison ivy. So let's talk a little bit about strategies for avoiding and dealing with poison ivy. The first thing you really want to do is you want to be able to identify it, and to avoid it. If you know you can't avoid it, there are preventative creams on the market that I've used to coat exposed skin. They have a waxy ingredient to repel the oil from the plant,

Jean: Long sleeve shirts, gloves, socks, close toed shoes, no sandals etc. By the way, this is good policy for tick avoidance too, so you can be a double threat to protecting yourself.

Linda: If you do come into contact with it, wash with cold water and soap or alcohol promptly. There are many other preventative detergents and soaps. The goal is to remove the oil.

Teresa: Once you have a rash, or reaction, there are many products on the market to relieve skin irritation. Remedies include over the counter, like Tecnu and calamine lotion, oatmeal based baths, and home remedies like alcohol, witch hazel, jewel weed, or a paste a baking soda and water can help alleviate symptoms. And I've also tried using a blow dryer, as the heat of the blow dryer will bring the histamines out, in order to temporarily relieve the itch.

Tim: Awesome. That's really interesting. I'll have to try that next time. In extreme cases, you really want to go to a doctor - consult a doctor who may prescribe antihistamines, steroids or prescription topical ointments.

Jean: The rash can last as long as two or three weeks. But there's good news here. You can't spread or catch poison ivy from touching someone else's rash. And the rash and fluid from the blisters are not contagious. It's only the oil from the plant that is toxic.

Linda: So how do you begin to manage the plant? Well, your goal should be to control it and you can't eliminate it. It's simply not practical to try to eradicate something that only the birds will replant.

Teresa: Poison ivy reproduces by seeds or rhizomes, so it's a persistent threat.

Tim: You want to dig out entire roots of individual plants when possible, solarizing with clear plastic and help with large patches, but it really isn't guaranteed. There may be still lots of roots there.

Jean: You can manage with herbicides in drastic cases.We have links and instructions to follow. Be very, very careful when you're using any of the herbicides.

Linda: And it never helps to burn it because the smoke can irritate your lungs.The smoke can carry the oils, onto you if you're downwind with exposed skin.

Teresa: So is it all beneficial? There is considerable wildlife value. The white waxy berries are popular with many songbird species like Robins, Catbirds, Grosbeaks and many birds eat insects on leaves.

Tim: Yeah, and dear browse it too. They enjoy the leaves that may be good news or bad news depending on what you think about deer.

Jean: What is not poison ivy? Virginia creeper, raspberries, blackberries, Boston Ivy, and groundnuts, are all mistaken for poison ivy. Also, many seedlings mimic poison ivy while they're young to get a head start on life. I was once scolded by a visitor to an open house for leaving poison ivy where people might touch it. She was irately pointing at a baby oak seedling that was just the right color, and had the right number of leaflets, to fool her anyway.

Linda: So there's two poison ivy these relatives that don't exist in our area, that being the Mid-Hudson Valley, but people think they do. Poison oak is a West Coast plant, and poison sumac only exists rarely in the Northeast. The poison sumac lives in very, very swampy areas. So we're not likely to encounter it. What gets the bum rap is Staghorn sumac. That's the one with the fuzzy red spikes and berries on top that looks like antlers. It's not poisonous. In fact, the Indians made sort of lemonade from the berries.

Teresa: Let's think about poison ivy and climate change. The scientific types of studying poison ivy to see how climate change affects the plant. Carbon dioxide increases seem to encourage it, and maybe even make the toxin and more powerful.

Tim: Oh brother, let me have one last word about that. You can get pictures of poison ivy to carry with you for many sites online. I like 'poison-ivy.org.' The US Fish and Wildlife Service also has a great brochure. If you haven't already, think about downloading the free app 'iNaturalist' or 'Seek' into your phone. It lets you take a picture and get it identified online. Links, as always, are on our website at: ccecolumbiagreene.org. I hope all of this information answers Carol's question. Good luck with your poison ivy!

You're listening to Nature Calls: Conversations from the Hudson Valley. Stay tuned for Good Plant / Bad Plant.

Tim: Hi, and welcome back to Good Plant / Bad Plant where we focus on two plants per episode; one that's ecologically valuable and often beautiful, and one plant on the other end of the spectrum that's invasive or noxious weed. That's good plant/bad plant. I'm your host, Tim Kennelty. Today I'm going to talk about an unbeatable plant that supports wildlife and is quite beautiful, too. I'm talking about the serviceberry, or also commonly called the juneberry or even shad bush or shad blow. Of course, the problem with common names is that sometimes one plant has more than one common name, or the common name may be used for several different plants. So today for clarity, I'm going to refer to this plant by its Latin name, Amelanchier, are small trees or shrubs, and are distinguished as one of the earliest plants to bloom, really a true sign of spring providing pollen and nectar to early emerging native bees and even butterflies. And the Amelanchier are in the rose family closely related to apples and have more than 25 different species that are native to the United States. And there's quite a few in the Northeast, like Arborea, Downey, and Allegheny and quite a few hybrids and cultivars like Autumn brilliance, Princess Diana, and Snowcloud. All of these have either enhanced flowers or beautiful fruit or bright fall color. Like most native plant species, Amelanchiers are not really terribly finicky, doing best and rich well-drained soil, or full sun or even partial shade. They're great planted along the edge of wooded areas or ponds or streams. I have quite a few along my pond, and they're really a gorgeous site in the Spring. And Amelanchiers are the quintessential multi-season shrub with a flurry of very early, drooping white blooms attractive blue fruit in June and sometimes spectacular fall color, depending upon the species or cultivar.

Tim: Amelanchier is a great all around wildlife plant because they supply nectar and pollen early in the season and have fruit in early summer that attracts more than 20 species of birds. They are also host plants for the beautiful hairstreak and viceroy butterflies, Luna moths and more than 100 other species of butterflies and moths. I consider Amelanchier years ago to bird plant as well. I'm told that the fruit can be eaten fresh off the plant or made into jam-- I've never tried this. I just enjoy watching the wide variety of birds literally stripped the plants clean when it's in fruit. So for a shrub or small tree with multi season interest and high wildlife, it's really hard to beat Amelanchiers.

Tim: Our villain in this episode is none other than the invasive bittersweet vine. This is one vine that many of us just love to hate. The face of bittersweet is a perennial vine native to China, Japan and Korea, and like many invasive plant species, was introduced intentionally as an ornamental plant in the 1860s. The bittersweet vine can pose a significant threat to native plant communities and ecosystems. It can grow rapidly up to 90 feet long, and it can kill or severely damage native trees and shrubs by girdling them and can shade out whole areas of vegetation. Its weight can also easily top a large trees and shrubs. Bittersweet can grow in a wide variety of soils, and while it really likes full sun, it can also grow in deep shade. It seeds are eaten by birds and it can be distributed long distances. Because the seed pods are attractive, people, including unfortunately, yours truly, before I knew any better, have been known to spread the seeds when it's been cut to make wreaths and other crafts. So, as I always say, know your foe: bittersweet can be best identified in the fall when it's fruiting. The fruit is a yellowish orange outer shell and a deep red globe. I'm going to include some links to help you identify the sign and especially to distinguish it from the native species of bittersweet, although it's relatively rare in our area. Like most invasives early detection is key and management may require committing to a multi-year plan.

Tim: Again, I'll include some links to provide more detail on how to manage this horrible beast. Bittersweet is really a very challenging invasive plant. I know it's really a headache for me, but it's well worth the effort if you are protecting valuable native trees and shrubs. So that's it for another edition of Good Plant / Bad Plant. And remember if you want to support wildlife in your yard, plant natives

You're listening to Nature Calls conversations from the Hudson Valley. Stay tuned for Hits and Myths.

Devon: Hi, I’m Devin Russ, a Master Gardener Volunteer from Columbia and Greene counties with hits and myths. Today I'm going to talk about companion planting. Carrots Love Tomatoes. That's the title of a very popular book about companion planting. Companion planting is the idea that crops will grow better next to other specific plants. Is that a myth? Well, we can't say the companion planting in general is a myth because plants certainly do affect their neighbors. But some of the particular claims are more myth than reality. Plants are affected by their plant neighbors in lots of ways. Some are purely physical, a tall plant can cast shade on its neighbors. A plant that spreads its leaves close to the ground can keep the soil moist by blocking the sun and the wind. A vine can climb over a neighboring plant and a neighbor with tall strong stems can let a vine grow high. A bushy plant can block the wind. A plant with thorns keeps grazers from eating its own leaves and the leaves of close neighbors. Gardeners make use of these physical interactions all the time. So for instance, you might hear suggestions to plant late crops of lettuce on the shady side of tall plants so lettuce can be a bit cooler. Or you might have heard of the Native American tree sisters gardens where beans were grown next to corn so that the bean vines could twine up the corn stalks. The third sister, squash, ran along the ground where the large squash leaves cast shade of the base of the corn and bean plants so weeds would not sprout and the soil would stay moist. These are very real and useful planting arrangements. But we tend not to be thinking of these purely physical considerations when we talk about companion planting. Companion Planting usually refers to plants that have some chemical, not just physical interactions, with their neighbors. For example, in a three sisters garden, along with the physical benefits of the plants give each other the squash and corn benefit from nitrogen added to the soil by the beans. Beans are nitrogen fixers. They have beneficial microbes growing on their roots that pull nitrogen out of the air and convert it into a form plants can use. All plants need nitrogen, but only the nitrogen fixers can use the nitrogen that is all around us in the air. That's why we add fertilizer to most kinds of plants. One thing to note though, is that the nitrogen in the roots of the beans doesn't benefit the corn and squash until next year when the bean roots have decayed into the soil. So this benefit is a better argument for crop rotation than for companion planting. Crop rotation is a proven technique. The most common companion planting recommendations say that strong smelling plants like garlic herbs should be planted next to your crop. The idea is that insect pests that are seeking the crop will be confused by the smell of the garlic herbs. It sounds convincing at first. But then you might think do insect pests really smell the same way we do? People don't rely much on our sense of smell. But many insects are able to navigate to a certain target plant, even in an environment with a great diversity of plants and other smells. They do this whether or not humans think their target plant has a strong smell. Monarch butterflies, for instance, are famous for relying on milkweed only to feed their caterpillars. But we don't think young milkweed has a distinctive smell. So there's really no reason to think that our ranking of strong smelling plants has anything to do with what might confuse an insect. Those who make claims about the use of strong smelling herbs to confuse pests have usually not tried to test them at all. The book, Carrots Love Tomatoes, for example, does not cite experimental evidence. When others have tested particular pairings of companion plants in a scientific way, the results so that the companion had little or no effect on the crop yield. Marigolds are the most recommended companion plant, both because they have, to us, a distinctive scent and because marigolds can interfere with nematodes in the soil, but the recommendation is very vague. There are many species of marigolds, and there are also unrelated plants, like calendula, that have the word marigold in their common names. There are also many species of nematode, and some are beneficial.

Devon: You don't know if you will be promoting a good result by planting marigold unless you know which species of marigold and which species of nematode. And really, who does know that level of detail. Marigolds themselves have pests, including aphids and slugs. So adding marigolds will attract those pets. So it's all very complicated. Boiling it down to marigolds make good companion plants is just too simple. And remember, the companion plants take up space. If your goal is to have lots of tomatoes from a small bed, you should be thinking, is it better to add a row of marigold as companion plants, or better to add one more tomato plant. If the marigolds are to be considered effective as companion plants, that would mean that you expect to get a bigger crop from five tomato plants with marigolds than from six tomato plants alone. And thinking about it that way makes it seem kind of unlikely. Of course, you might want to plant some flowers in your vegetable garden because you enjoy seeing them there. But companion planting schemes can be very complicated. You can find charts and tables detailing what should go with what before you let yourself feel stressed about whether you are maximizing that benefit for your garden, remember that almost none of the companion planting recommendations are supported by strict evidence. Thank you for listening. This is Devon Ross with Hits and Myths.

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That concludes another episode of Nature Calls: Conversations from the Hudson Valley. We'd like to thank Sandra Linnell and Devin Connolly from Cornell Cooperative Extension of Columbia and Greene counties for production support. And a special thank you to our listeners for joining us on this episode of Nature Calls: Conversations from the Hudson Valley. You can find links to any of the topics mentioned in this episode at our website at CCEcolumbiagreene.org. Comments and suggestions for future topics may be directed to us at ColumbiagreeneMGV@cornell.edu or on the CCE Master Gardener Volunteers of Columbia and Greene County's Facebook page. For more information about Cornell Cooperative Extension of Columbia and Greene counties, visit our website at CCE Columbia green.org or visit us in Hudson or in Acra. Cornell Cooperative Extension provides equal programming and employment opportunities.

Last updated May 3, 2023