Pacific poison-oak
Pison-sumac
Black locust
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 ap- pear 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 en- vironmental conditions that increase exposure risk of poisonous plants for tree care workers. “Contact from the leaves can be worse in spring and summer,” Watkins re- ported. 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.
urushiol (yur-oo-shee-aal). Once the oil touches clothing, skin, shoes, or equip- ment, 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 uru- shiol 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 responsi- ble for psoriasis).
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, man- ager 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 cau- tioned. PREVENTION STRATEGIES According to McCallister, identification is key to preventing a negative encoun- ter 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.
26 | ArborTIMES Fall 2024
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