Wright County Soil and Water still working to control wild parsnip

Sept. 29, 2008

By Kristen Miller
Staff Writer

Wright County, MN – With the invasive species of wild parsnip getting out of hand, the Wright County Soil and Water Conservation District is doing all they can to nip it in the bud.

Currently, Wright County Soil and Water is forming a Cooperative Weed Management Area Group and hopes to include as many township, city, and lake association officials in the mix as possible.

The objective of the group is to “put heads together” and find remedies for problem areas, according to Brian Sanoski, a resource conservationist with Wright County Soil and Water.

Since completely eradicating the rapidly spreading plant is unlikely, Sanoski and others alike, are doing their best to control and maintain the weed.

Now, with a “good map base” of where the perennial is growing, which includes in the ditches and beside railroad tracks along Highway 12, the group is experimenting with what works best to control and kill it.

The control methods that seemed to work the best, according to Sanoski, was cutting just beneath the crown of the root with a shovel.

“The only problem with this is it is rather labor intensive,” he said.

As far as chemicals, the chemical Curtail, a broad-leaf killer, seemed be most effective without killing or damaging surrounding grasses, he said.

The sap from wild parsnip is toxic and should be avoided because it can cause a very painful rash, blistering, or discoloration of the skin.

It is most irritating at the time of flowering, from June through September.

For more information about the Cooperative Weed Management Area Group or wild parsnip in general, contact Wright County Soil and Water Conservation District at (763) 682-1970.

Mechanical methods

The following are recommendations from Wright County Soil and Water on ways to control and maintain wild parsnip. When using any of the methods, one should avoid direct contact by wearing gloves, long sleeves and pants.

Hand pulling: Grip the plant stalk just above the ground and pull the plant from the ground. Works better in saturated soil and drought like conditions when the tap root shrinks. Results have an effect on removing the plant stalk, but re-growth occurs from the taproot. The plant will need to be removed multiple times throughout the year to ensure there is no seed production.

This is found to be most effective year round before the plant goes to seed. If hand pulling after viable seeds are produced, the plants must be collected and burned.

Cutting the root: Using a spaded shovel or object with a blunt edge, cut the wild parsnip root approximately one inch below the ground. Make sure the cut is just below the crown of the plant root. For ease of cutting root, after rain events when the ground is soft are ideal conditions. Results have illustrated 100 percent mortality rate when cut.

This is found to be most effective year round before the plant goes to seed.

Burning the seeds: After the plant has gone to seed and chemical spraying is no longer a possibility, burning the seed from the plant with a torch is a possibility.

Burning the seed should be done after rain to avoid starting fires on private and public land. Sanoski burned the viable seed, collected, and germinated them along with a control seed from the same plant. This was done by placing the seeds in Petri dishes with napkin, water, and sunlight for approximately three weeks.

The results from this experiment proved 35 to 40 percent of the control seeds germinated, where 0 percent of the burned seeds germinated.

This is most effective after the plant has turned brown and seeded. When green flowering plants and plants with green seeds were burned there were hardly any impacts to the plant.

Cutting and collecting the seed: Once the plant has gone to seed and is viable, cutting the tops of the plants with a scissors or clippers and bagging the seed will reduce the number of viable seeds.

This collected seed will then need to be burned instead of thrown away to ensure viable seed is destroyed. Once the stalk of the wild parsnip plant becomes woody the plant becomes fragile and when cutting some seeds maybe lost during the process. However, the vast majority of the seed is collected this process is not flawless.

This method is most effective after the plant has turned brown and seeded.

Mowing: Cutting wild parsnip with a mower can cause more harm than good when trying to eliminate. If mowed too early in the year wild parsnip will re-sprout like a stump sucker on a tree sending out two to three plants. These plants will mature, flower, and produce viable seeds. When mowed the plants re-grows six to eight inches in height and produces seed, but not nearly as many as originally.

When mowed too late the viable seeds can be spread amongst the site and be transported elsewhere from riding on mower decks or other parts of the machine. Cutting early and cutting often is the only way mowing is efficient.

This method is most effective from early spring until plants produce seed.

Chemical Methods

Two and Four-D and Weed-B-Gone: Commonly used as a dandelion eliminator, these chemicals have proven to be effective early in the year when plants are still in the rosette stage and second year plants six to eight inches. Chemical has little effect on flowering and larger plants unless mixed at or above labeling instructions.

This is most effective in early spring when rosettes are first visible until plants grow to 8 inches in length

Curtail and Crossbow (with a surfactant): These broad leaf products are great for ridding areas of parsnip without harming the surrounding grasses and native species. Results have shown these chemicals to kill wild parsnip at most plant stages with the exception of when plant stalk has turned woody and seed is already viable.

This method is most effective from early spring until the plants turn woody and produce viable seed.

Round Up and Ranger: These products active ingredient is Glyphosphate, when applied to the plant any additional over spray or chemical dripped on surrounding area will kill all forms of vegetation. A Glyphosphate product does a wonderful job on wild parsnip, but spray sparingly to avoid additional removal of desired vegetation.

This is most effective from early spring until the plants turn woody and produce viable seed.

Interesting facts

• Wild parsnip seeds slit forming two seeds, doubling the count per plant

• Dense forest cover and wetland areas impede the spread of wild parsnip

• Wild parsnip is a phototoxic making no one immune to the blisters formed from the sap and sunlight

• Wild parsnip has potential to germinate the same year seeds are released onto the ground

• There is a natural predator, the parsnip moth, which will attack plants only when plant is damaged.

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