Monday, October 21, 2019

Noxious weeds bring economic hardship to the Kansas landscape. Common noxious weeds found in Marion County are musk thistle, field bindweed, and johnsongrass. These weeds have been designated "noxious" by the Kansas Legislature. Although, definitely obnoxious, Poison Ivy, a social problem weed, does not exhibit the economic damage to property required to be classitled a noxious weed. Poison Ivy (Toxicodendron radicans) is commonly found throughout Marion County and the State of Kansas. Poison Oak does not exist in the county and is rare in Kansas.

Common Poison Ivy is identified by its alternate, trifoliate, compound leaf. The leaf is divided into three separate leaflets. This is where the term "Leaflets three, let it be" comes from. Leaflet margins can vary greatly from being smooth or entire to lobed or toothed. These leaflets are slightly pubescent along the midrib, shiny, and will rum yellow to deep red as fall and cooler temperatures approach. In late summer, this perennial plant will produce creamy-white, globular, fruit 5 mm in diameter that cluster in grape like bunches. .Upland gamebirds and wild turkeys will consume and spread the fruit and seeds.

Poison ivy may grow as a vine or shrub. Vines will trail along the ground or vigorously wind around the branches of a tree or other objects for support and reach considerable heights. Isolated .shrubs can attain heights of 3 feet. It will thrive under a variety of conditions. Plants seem to like shade, but do well in sunny locations. The oily irritant in Poison Ivy is called urushiol. It is present in the plant's sap and is found in all parts of the plant. The typical skin reaction and blisters associated with Poison Ivy can appear from contact with dormant and dead plant parts as well as live ones. Be especially careful of leafless dead vines on firewood in the winter . Burning Poison Ivy releases the urushiol toxin into the air and a severe reaction can occur from inhaling the smoke. The urushiols can chemically lock in to the proteins of the skin within 20 minutes of exposure. It causes Rhus dermatitis in 50% - 75% of people, but animals are seldom susceptible. Washing with soap and water is most effective if done within 5-10 minutes after contact with the plants. Itching is the first symptom of poisoning. If inflammation increases, blisters form on the skin. Broken blisters do not spread the infection.

Mechanical removal of the plant can control Poison Ivy. Removal is safest and easiest in late fall or early spring when the plants have no leaves. Precautions should be taken to cover exposed skin when handling Poison Ivy. Gloves and clothes should washed separately ,with hot water and strong soap. Poison Ivy reproduces by seeds and rhizomes, so the entire plant must be removed, including the roots.

The use of herbicides is the most successful way to kill Poison Ivy. For modern herbicides to effectively control Poison Ivy, the plant should bc in the full leaf stage and actively growing. In Marion County, the best control dates are between June 15 and August 1. Wet leaves with the spray mixture until runoff occurs. Normally a single treatment cannot be expected to kill the plants entirely. Watch for reoccurring growth and retreat as needed. Cutting a section out of the vine trunk and applying a systemic herbicide concentrate to the freshly cut stump surface can control Poison Ivy climbing in trees. In herbicide sensitive areas a non-residual herbicide product can be wiped directly on the leaf surface with a paintbrush or cloth. Total plant coverage is not necessary for good control;

The herbicides listed are registered for use on Poison Ivy. No endorsements are implied, nor discrimination intended.

Trimec -(Dicamba + 2,4-D -I 2,4-DP)

  • yards and other grassy areas
  • Spot applications
  • Kills poison ivy and other broadleaves, but does not kill grass

Brush Killer- (triclopyr)

  • yards and other grassy areas
  • fence rows
  • spot applications
  • waste areas
  • cut stump section treatments
  • Kills poison ivy and broadleaves, bur does not kill grass.

Roundup- (Glyphosate)

  • spot applications
  • selected garden and flower bed areas
  • windbreaks and nature areas
  • spot wiping applications

Kills poison ivy and all other green vegetation with no residue


Hoeing or cutting every three weeks will reduce poison ivy

  • cut stumps should be treated immediately for best results
  • poison ivy does not grow well in deep sandy soil


Contact your local garden center, farm store, or herbicide dealer to purchase herbicide control products.