Noxious Weeds

Bull thistles are biennial plants, meaning they live for two years. They begin as a small rosette of leaves and build up energy over the season. The following year they will send up five foot tall stems that produce flowers. After that the life cycle is complete and the plants will die.

Canada Thistle is an invasive weed that is native to Europe and Asia. This is odd as many people believe that it originates in Canada due to its name. The plant now grows in 37 countries around the world and is widespread throughout the United States.

Multiflora rose was once planted for many uses including conservation, living fences, and ornamental purposes. It was once thought that the plant would make good wildlife habitat and help control erosion. Unfortunately, this rose grows aggressively and creates dense thickets where no other plants can grow and wildlife cannot live. Fruit from Multiflora rose is bright red and attractive to birds that eat and spread the seeds as they are done digesting the fruit. Seeds can still grow 20 years after being dropped in the soil. Fields, forests, and prairies are easily overrun, severely degrading habitat quality.

Musk thistles start as a rosette of spiny leaves with a light colored midrib and a frosted appearance around the edges. In their second year of growth the plants will bolt, sending up long shoots with flowers. After the plant produces seeds it dies.

Perennial Sowthistle has flowers that resembles the dandelion flower. It can spread aggressively with windblown seeds. Small pieces of root left behind can become new plants, making removal difficult. This thistle prefers disturbed areas and moves in quickly. It is best controlled by spraying with herbicide or hand pulling, being careful to get the entire root.

Poison Hemlock can grow to be eight feet tall. It has hollow stalks with purple splotches. The flowers are umbels of smaller umbels that flower in the late spring. This plant is very toxic to humans and animals. If ingested signs will begin twenty minutes to three hours later. Do not pull with bare hands. Use gloves if removing a large patch. If a larger patch must be removed, mow just before flowers come on in the spring or treat with an herbicide.

Quackgrass can be identified by looking closely at the point where the end of the leaf wraps around the stem. If you find two finger like projections (auricles) wrapping around the stem you have probably found quackgrass. This grass has deep root systems with rhizomes meaning it can reproduce underground and grow out before growing up and emerging from the soil. If you till quackgrass you will scatter the plants around and they can regrow causing an even larger problem. Quackgrass cannot tolerate shade so plant crops that will grow quickly and shade out the grass before it can grow. You can also use a high rate of herbicide to kill it.

When Shattercane is a seedling it can look similar to corn or johnsongrass. It grows in tufts becoming nearly seven feet tall. Leaves have a pale midvein. As the plants mature the seed head will begin to droop slightly. Shattercane is an aggressive row crop invader. It can be difficult to remove once it gets into other crops. The grass can hybridize with same species and create more varieties of the plant to control.

Teasel was first introduced to the United States in the 1800s. It was brought here to be cultivated for use in textile processing. The dried flower heads were used on spindles to raise the nap of woolen cloth by textile workers.

The plants are tall, thistle-like biennials. This means that the plants take two years to grow and set seed. First year plants are a cluster basal leaves that store energy for the coming year. This is often the best time to control these plants. Second year plants bloom between June and October and often reach heights of up to 8 feet. A single plant can produce more than 2,000 seeds which can remain viable for at least 2 years.

Teasel is often found in sunny fields, roadsides, disturbed areas and waterways. Teasel can also invade lightly managed grasslands as well as high-quality natural areas.

Wild carrot has large white umbel shaped flowers. Often the middle flower of the umbel will be purple. The plant can grow to be two to five feet tall. It blooms mid summer to fall. After the plant flowers it produces fruit. The umbel curls up a round the fruit and when it detaches from the plant it is able to be rolled by the wind. As it rolls it drops the seeds a long the ground.

Pull the plants or mow them before seeds come on. Use gloves if hand pulling as some members of the carrot family can make skin sensitive to sunlight. Application of herbicide can also remove the plant.

Wild Mustard grows to be between one and three feet tall. The stems are covered in fine white hairs that point down. It has alternate leaves that vary in shape and get smaller as they go up the stalk. Yellow flowers with four petals make this plant easy to spot in a field.