Seedling plants at the end of the first year have well-established rootstocks that only digging, grubbing, or herbicides will kill.
Seedlings will persist as long as seedbearing plants are in the general area. A single tillage event is of little value in combating Pacific poison-oak and western poison-ivy, but multiple tillage operations for seedbed preparation and planting of cultivated crops for 1 or 2 years will provide control. Though some animals, such as sheep and goats, graze Pacific poison-oak and western poison-ivy and may limit abundance of those plants, grazing will not eliminate these weeds or stop their spread unless it continues intensively for several years.
No parasitic insects, pathogens, or microorganisms have been found to suppress Pacific poison-oak or western poison-ivy. Several commonly available brush-management herbicides may be used to control Pacific poison-oak or western poison-ivy.
Specific recommendations will depend on the type of land small woodland, commercial forest, public recreation area, etc. Consult the resources for more detailed information.
Products containing glyphosate are nonselective and have the capacity to kill or injure all plants, while others, including dicamba and triclopyr, are selective only to broadleaf plants, including desirable trees and shrubs.
Glyphosate and growth-regulator herbicides including 2,4-D, triclopyr, and dicamba can damage valuable plants such as ornamentals and must be carefully applied. Selective herbicides can remove Pacific poison-oak and western poison-ivy without destroying desirable grass. However, products containing glyphosate and triclopyr are likely to be the most effective and affordable over time. These products may be purchased from most agricultural supply companies, and some of these herbicides may also be obtained in pre-mixed, ready-to-use forms in small consumer packages in lawn and garden stores.
Herbicide application timing depends on the application method. Foliar treatment of established plants should be done in the late spring or early summer June in most areas after Pacific poison-oak or western poison-ivy are in full leaf. Any foliage regrowth and plants that were missed should be resprayed the same year during the fall, prior to leaf drop.
Herbicides may drift if sprayed during breezy conditions and may volatilize and move off-site in warm weather. Careful application is required in areas where susceptible plants are growing; only treat the desired plants during application. Pacific poison-oak and western poison-ivy can also be effectively controlled by treating the lower stems basal bark methods with herbicides and adjuvants registered for such uses during the winter, when the plants are leafless and dormant.
Winter application is relatively safer than in other times of the year because there are fewer ornamental and other valuable plants actively growing that may be injured by carelessness or accidental spraying.
Also, leafless stems provide less chance of the applicator being exposed to the oils produced by the plants. As with most perennial weeds and unwanted vegetation, repeated applications over several years are needed for complete control. Center for Disease Control factsheet. Poisonous Plants. Gladman, A. Howard, Janet L. Toxicodendron diversilobum. Innes, Robin J. Toxicodendron radicans, T. National Capitol Poison Control factsheet.
Prather, T. Mild cases can be treated with over-the-counter medications aimed at minimizing itching. Antihistamines such as Benadryl can be taken orally. However, you should avoid using topical Benadryl cream for large rashes, as this can sensitize your immune system in much the same way that urushiol does, potentially causing a severe reaction if you were to take oral Benadryl later.
Drying agents like calamine lotion can help relieve itch and dry seeping areas. Oatmeal baths can also be soothing and provide some relief. Your clinician will likely prescribe a day course of steroids; shorter courses are often inadequate and lead to a rebound exacerbation of the rash when the drug is stopped.
As soon as you can after being exposed to the plant, wash all affected areas with warm, soapy water. Some over-the-counter soaps, such as Technu or Zanfel, are designed to help remove the plant oils from human skin, but regular soap works, too. Washing your skin within 10 minutes of exposure can minimize your risk of a reaction. All exposed surfaces—including your skin, clothing, car seats, and even pets—should be washed as well. Although pets are unaffected by the oil, they can carry it on their fur and easily pass it to humans.
Unless thoroughly washed off, the oil from the plants can remain on objects for years, causing symptoms when you come into contact with the oil again. There are a number of steps you can take to protect yourself against poison oak, ivy, and sumac.
The allergen is absorbed into your skin when you touch the plant. The best way to prevent poison oak rash is to learn to recognize the plant and avoid contact with it. The most obvious evidence of an allergic reaction is skin rash, also called dermatitis. First, you may notice some stinging, itching, and minor skin irritation. Eventually, a red rash breaks out that gets itchier as it progresses. The rash will be worse in the areas that had direct contact with the plant.
Bumps will start to form and eventually turn into large blisters that ooze liquid. Within a few days, the blisters begin to dry up and form a crust. Poison oak rash is most likely to appear around your wrists, ankles, and neck, where the skin is thinner. The rash usually peaks about a week after exposure and lasts 5 to 12 days. In rare cases, it can last a month or more.
Signs of a severe allergic reaction include:. Most of the time, poison oak rash can be treated at home. Wash your clothes and anything else that may have come into contact with the poison. The oils from the plant can remain on fabric and other materials and can give you another rash.
Also wash your body well with plenty of lukewarm water and soap. Pay special attention to your hands, fingernails, and whatever skin may have touched the plant.
The rash can be very itchy and the temptation to scratch is strong, but scratching can cause an infection. Touching the blisters can also result in infection. Take lukewarm baths or cool showers to ease itching. Another difference between the two is that Virginia creeper vines are much less hairy than poison ivy vines. Virginia creeper has fewer, more widely spaced rootlets, and some rootlets have small attachment disks at the ends figure 7.
Only rarely does contact with Virginia creeper leaves or stems cause an allergic reaction in sensitive individuals. The plant is generally considered harmless, although the fruit can be harmful if eaten. Box elder Acer negundo seedlings have leaves with three leaflets and can look like poison ivy at first glance. Box elder leaves, however, are arranged opposite each other along the stem figure 8 ; poison ivy leaves are arranged alternately along the stem.
Climbing hydrangea Decumaria barbara vines are hairy and may appear very similar to poison ivy, but they have opposite, simple leaves with smooth edges or just a few shallow teeth figure 9.
Fragrant sumac Rhus aromatica is often mistaken for poison oak, and both grow in similar habitats. One difference is that the leaflets of fragrant sumac are attached at a single point, while the terminal leaflet of poison oak has a short stem. Also, the fruit of the fragrant sumac plant is red figure Smooth sumac Rhus glabra and winged sumac Rhus copallinum are commonly occurring shrubs that may be mistaken for poison sumac, but there are several clear differences. The leaflets of smooth sumac have teeth along the edges and are greater in number eleven to thirty-one than those seen in poison sumac figure Winged sumac is easily identified by the leafy wings along the leaf stalk figure Neither species is likely to cause skin irritation, although some people may be sensitive to the sap.
The fruits of both nonpoisonous sumacs are red figure 13 , unlike those of poison sumac. Touching any of the three poisonous species may result in a red, swollen, and painful rash of itchy blisters. Rashes can occur in patches or in streaks and lines. About 85 percent of people are allergic to urushiol, the oily compound responsible for the skin reaction. Urushiol is found in all parts of these plants. Simply touching the leaves may expose you to the oil, and additional oil is released when plant parts are crushed or damaged.
The oil resists breakdown and may cling to clothing, tools, and pet fur for long periods of time, even a year or more. Exposure to the oil on these secondary sources can also cause an allergic reaction.
Not everyone is allergic to these plants, and sensitivity varies between people, but allergies may develop with increased contact. People suffering from a rash caused by these plants need not worry about spreading it to other parts of the body or to other individuals. After the rash appears, it is not contagious, and any observed spreading of the rash is the result of a delay in reaction from previous exposure or from re-exposure due to contact with clothing and equipment that has not been properly cleaned.
Although the rash may be visible in as little as a few hours, it may take up to 3 weeks for the entire rash to appear. In mild cases, hydrocortisone creams or other anti- itch creams can be applied to soothe irritation. Some products are marketed specifically for treatment of poison ivy and poison oak rashes and can be obtained over-the-counter at local pharmacies.
Calamine lotion and oral antihistamines also can provide some relief. Most cases will clear up in a matter of weeks without further medical attention. Approximately 10 to 15 percent of people will have reactions severe enough to require medical treatment, often in the form of oral or injected low-dose steroids administered by a doctor.
Seek medical help if the rash becomes infected, covers a large part of the body, causes swelling of the face or other sensitive areas, or causes difficulty with swallowing or breathing.
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