A Master of Disguise, Poison Oak is Sometimes Difficult to Spot
Quick Facts
- Poison oak contains urushiol oil, which causes what is believed to be the most common allergen in the U.S.
- It only takes 1 billionth of a gram of urushiol oil to cause a rash–500 people could itch from the amount that would fit on the head of a pin.
- Poison oak has been called the most hazardous plant in California because of work hours lost and workers' compensation claims filed after getting a rash.
- Burning poison oak can cause severe respiratory irritation, even death.
Problem/Diagnosis
Poison oak, poison ivy and poison sumac are all found in most areas of the U.S., except Alaska, Hawaii, and some parts of the Southwest deserts. Poison oak is more commonly found west of the Rockies, extending from British Columbia south to the Baja California peninsula. Poison oak mainly grows in the western portions of Washington and Oregon, but in California it’s more widespread and can grow from sea level to about 5,000 feet, in woodlands, grassy areas, forests and more.
Poison oak closely resembles poison ivy. In open, sunny areas it forms a brushy, leafy shrub that grows between one and six feet tall. In the shade, it takes on the form of a vine and grows much taller by climbing on other objects.
It is a master of disguise as its leaves are similar to those you’d find on an oak tree, but there is a major difference. Poison oak leaves are clustered in groups of three, five or seven, but true oak leaves grow singly. With undersides that are much lighter green than the tops, poison oak leaves are smooth-edged and can be covered with little hairs. In early spring the young leaves are green or light red, then turn glossy green in late spring and summer. In the fall, they turn orange and red, before falling off in the winter. (Insert photos of poison oak)
Poison oak contains urushiol oil—the sticky, resin-like substance found inside the plant that causes the rash, blisters and itch that make it so well known. More than half the population is allergic to urushiol oil. Found in poison oak, poison ivy and poison sumac, it is said to be the cause of more than 50 million cases of dermatitis in the United States every year.
Urushiol is present throughout the entire plant, including leaves, stems and roots, even after the plant has died. It can also stay active on any surface for up to five years–including on dead plants, yard tools, garden gloves and even animal fur.
Solution
How can you take control of poison oak before it takes over your yard? Keep your lawn and fence line clear and trimmed, and cut back the undesirable plants to ground level every time you see green growth. Bayer Advanced™ Brush Killer Plus Concentrate and Bayer Advanced™ Brush Killer Plus Ready-To-Use are easy-to-use alternatives that kill the brush down to the roots so they won’t come back. It controls poison oak and 70 other types of weeds and brush roots and all and it starts working in just one day.
Brush Killer Plus is available in both a concentrate and a ready-to-use, no-mix formula with nested sprayer for easy application and neat storage. Always wear protective clothing when working near poison oak.
Always read and follow label instructions.
Products Mentioned In This Article
Bayer Advanced
