Navigating Toxic Plants

Essential Safety Tips for Poison Ivy, Oak, and Sumac

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Encountering toxic plants such as poison ivy, oak, or sumac may be inevitable in the tree care industry, but suffering from them is not. With preventative measures, knowledge and education, and prioritizing safety, workers can protect themselves from these itchy pests.

Exposure to toxic plants can lead to an itchy rash, blisters, and swelling, but it can also be more serious.

Other severe symptoms that require immediate medical attention are difficulty breathing, a rash around the mouth, eyes, or genitals, swelling on the face, a rash on more than 25% of the body, or fever. According to the American Skin Association, approximately 10-15% of the population is highly allergic.

“While prevalence may seem minor, it can easily become serious enough to warrant medical attention, which is why poison ivy and poison oak should be some of the first plants a tree worker learns to identify,” said Blake Watkins, ISA Board Certified Master Arborist (BCMA), Registered Consulting Arborist (RCA), and operations partner at    Monster Tree Service, said.

Common poisonous plants in the tree care industry are poison oak, ivy, and sumac, but stinging nettles, giant hogweed, and wild parsnip also pose threats. Some trees, like hawthorn, Black locust, and some varieties of honey locust have long thorns that can easily pierce the skin.

Although the trees themselves are not poisonous, the thorns of Black Locust and Hawthorn are host to a number of different bacteria that can cause serious allergic reactions if the skin is punctured.

“Your safety and your crew’s safety are always number one,” Ben McCallister, urban forestry specialist at Purdue University, said.

McCallister reports an encounter one of his workers had when a small sliver of thorn was accidentally left beneath the skin when he was pricked by a Black Locust thorn.

“He almost had to amputate the finger,” McCallister said. “He had to take two or three months off work.”

Understanding the Risks

Poison oak, ivy, and sumac all produce the oil,

urushiol (yur-oo-shee-aal). Once the oil touches clothing, skin, shoes, or equipment, it can spread through touch.

For example, if a pet runs through a patch, then climbs into the car, it can transfer the oil from its fur to the car.

Likewise, if tools touch the plant, then the oil can transfer from the tools to the car interior, which can also get on clothes, which can transfer to the skin.

Furthermore, the risk of getting a rash does not diminish even when the plant is dead.

Nearly everyone is allergic to this oil, and the leaves, stems, and roots all carry it.

“The vines actually hold more oil than the leaves,” McCallister added.

Everyone that is reactive to the plant experiences the same mechanism that causes the allergic reaction. When someone touches the plant, the urushiol oil is absorbed through the skin within half an hour.

Specialized skin cells (Langerhans) send a signal to the body’s immune system which will then produce a protein that causes inflammation and itchiness (the same protein responsible for psoriasis).

Despite the speed of absorption, the rash itself is typically more delayed.

If someone has never been in contact with poison ivy, then the rash will appear in two to three weeks. However, if they have had a previous rash, the onset is much quicker, within just four to 48 hours.

High-Risk Situations for Tree Care Workers

There are seasonal variations and environmental conditions that increase exposure risk of poisonous plants for tree care workers.

“Contact from the leaves can be worse in spring and summer,” Watkins reported.

Poison ivy’s dormant season is in late fall to early winter when the leaves have fallen off the vine.

“However, the risk of overlooking the plants is greater in the fall and winter when the stems are more likely to be inadvertently cut,” he added.

Some maintenance tasks heighten the risk, such as cutting, pruning, and clearing. There are even a few typical tree removal techniques that should never be employed with poison ivy, oak, or sumac.

For example, if your team identifies the presence of poisonous plants at a worksite, it is best to avoid chipping or using a chainsaw on the plant. These activities release dust into the air, which, when breathed in, can cause a severe — and dangerous — reaction in the lungs.

“The dust of poison ivy is also very toxic. During the summer, when dust carries, we’ll wear medical masks, to cover our mouths,” Chris Kemp, manager of the tree and plant divisions of Piscataqua Landscaping, said.

“Don’t burn it either because the smoke can carry particles, too.”

Kemp uses a combination of cutting the plant at the base, then administers Roundup on the plant wound.

“But it’s a persistent pest, so multiple applications are required,” he cautioned.

Prevention Strategies

According to McCallister, identification is key to preventing a negative encounter with hazardous plants.

“Learn how to identify it. It’s [about] having a really good training setup… and making sure everyone can identify it,” McCallister said.

The saying goes “leaves of three, leave them be,” but this hardly covers the nuances of all the hazardous plants tree care workers may encounter.

Poison sumac has seven to 13 leaflets and grows as a tree. Eastern poison ivy is usually a hairy vine with three shiny green leaves (red in the fall), whereas Western poison ivy still consists of three leaves as a shrub, not a vine.

Watkins advised that when evaluating a site, the sales arborists or team leads need to note all possible environmental hazards then make a plan for the field team to avoid them.

There are also a few digital tools that can help identify these leafy hazards.

Apps like Seek use databases to identify plants in real time, even without an internet connection. That said, mistakes can happen, especially during dormant months.

Ultimately, if an arborist is unsure about a plant species, they should get a second opinion.

“If you can’t ID these plants, I would recommend taking a photo and texting it to someone who can,” Watkins said.

Recommended attire for working with poisonous plants is similar to standard safety-wear: long sleeves, long pants that cover the ankle, eye and ear protection, and sturdy boots.

“The key is coverage. Remember that once you touch a toxic plant that has oils, it will stay there,” Chris Kemp said.

McCallister reports that it is vital when working at a tree site to know the species and to have the correct protective equipment.

“Leather gloves work with barbary but they aren’t good for poison ivy,” McCallister said. “The leather will keep the oil on them after.”

First Aid

If you happen to come in contact with a hazardous plant, clean, disinfect, and treat any exposed skin so that the oil does not continue to spread and cause further symptoms. Just as important is properly cleaning your gear as well.

For tips on how to care for your exposed gear, turn to our article on personal protective equipment (PPE) on page 32.

Removing the Irritant

There are a few techniques to remove the urushiol oil from one’s skin.

The first is to pour rubbing alcohol on the infected area. Oil will dissolve in alcohol, and the alcohol will draw the oil out of the skin. As the alcohol is drained away, so will the urushiol oil.

The second step is to wash the area with soap and lukewarm water. Avoid using soap as the first step because soap is simply an emulsifier, which means it will break down the oil into smaller droplets, which can still spread over the skin.

Do not scrub too hard or else the top layer of skin may be exposed, stripping the layers the oil needs to penetrate. At this point, it is important to not return to an area with poison ivy because the skin’s natural protective oils have been washed away.

Treating the Rash

If there has been an exposure and a rash develops, then they will generally go away within two weeks. In the meantime, treatment includes over-the-counter medications.

Products that dry out the skin, such as Burow’s solution, calamine and witch hazel can help reduce itchiness. They can be applied 2-4 times per day for a maximum of 7 days. Oatmeal baths can also help.

Blisters may form and even break open, but the liquid that oozes is, contrary to popular belief, not more urushiol oil. As painful as the blisters may be, they should not be popped, as exposure to air means they may become infected.

The same goes for scratching — as hard as it may be, resist the temptation! Scratching may tear the skin and lead to a more serious infection. Instead, try cool compresses and medicated soaks like Domeboro.

Other OTC medications include any astringents containing aluminum acetate. Antihistamines, such as Benadryl, do not work with poison ivy.

Avoidance is the Best Remedy

Ultimately, ongoing education and communication within the team of tree specialists is critical for avoiding an incident with any toxic plant.

“Share stories of encounters and close calls so everyone can learn from each other’s experiences,” Watkins said.

Kemp underscores the importance of daily or weekly safety reminders.

“Repetition is key,” said Chris Kemp. “It’s just common sense.”