Integrated Roadside Vegetation Management

Overview

In 1987, the Story County Board of Supervisors, in cooperation with the Story County Engineer and Story County Conservation, decided to take a new approach to roadside maintenance.

The Integrated Roadside Vegetation Management Program (IRVM) was developed to provide a cost-effective, environmentally safe management alternative to conventional chemical and mechanical management practices. IRVM maintains a safe travel environment on the county right-of-ways, controls noxious weeds and soil erosion, sustains water quality, improves wildlife habitat, and provides the public with aesthetically pleasing roadsides.

6 Reasons Why the IRVM Program is Important to Story County

• Roadside plantings are a long-term plan for cost savings.
• Native plants help drivers in the winter
• Native plants are important to pollinators and other wildlife
• Roadside plantings beautify the landscape.
• Native plants resist the spread of invasive species.
• Native plantings preserve our natural heritage.

Prairie Preservation

Prairie once covered 85% of Iowa. Today, only 1/100 of 1% of Iowa is protected and managed as prairie. Iowa’s native roadsides help prevent soil erosion and provide important habitat while promoting the use of prairie statewide.

IRVM is also available to provide technical advice for every aspect of prairie management. Our private lands program can help you with everything you need; from preparing your land for native species to advice on species selection. In addition, several different pieces of equipment are available for rent. Please contact the IRVM office at 515-382-7367 for more information.

Weed Control

The IRVM office is also responsible for upholding the Iowa Weed Law (Chapter 317, code of Iowa) within Story County. Historically invasive species have always been a problem in the roadside, but the county Weed Commissioner oversees the control of noxious weeds on all public and private property.Controlling noxious weeds is an important aspect of responsible land management. If noxious weeds are left uncontrolled they can cause severe economic and environmental loss. Weeds may be controlled in the following ways:

Spot Spraying

A technique that uses herbicides to spot kill weeds. It targets specific weed problems like Canada thistle, musk thistle, and giant ragweed. Selected herbicides used are effective, yet environmentally sensitive. In the past, blanket spraying killed or stressed many plants in the roadside resulting in weedy vegetation and water quality issues. It was also very expensive.

Controlled Burning

Requires proper weather conditions, equipment, and management skills. Rotational burning at the right time can boost native vegetation historically linked with fire to promote growth. Many weedy species are not fire-adapted. Brochures on roadside burning are available. For more information, contact the IRVM office.

Mowing

Used to reduce seed proliferation, improve site distance at intersections and signs, and to reduce snow drifting. Limited mowing also decreases equipment maintenance, fuel requirements, and labor costs.

A healthy and diverse native planting can be relatively weed resistant. To promote healthy plantings, IRVM uses a diverse native seed mixture and limits disturbance in the right-of-way. Disturbance concerns include; off-label herbicide use (overspray), excessive water movement, and soil erosion.

The Story County IRVM program is responsible for upholding the Iowa Weed Law (Chapter 317, code of Iowa).

The Iowa Weed Law defines noxious weeds as:

Primary noxious weeds

• quack grass (Agropyron repens)
• perennial sow thistle (Sonchus arvensis)
• Canada thistle (Cirsium arvense)
• bull thistle (Cirsium lanceolatum)
• European morning glory/field bindweed (Convolvulus arvensis)
• horse nettle (Solanum carolinense)
• leafy spurge (Euphorbia esula)
• perennial pepper-grass (Lepidium draba)
• Russian knapweed (Centaurea repens)
• buckthorn (Rhamnus, not to include Rhamnus frangula)
• all other species of thistles belonging in genera of Cirsium and Carduus

Secondary noxious weeds

• butterprint (Abutilon theophrasti) annual
• cocklebur (Xanthium commune) annual
• wild mustard (Brassica arvensis) annual
• wild carrot (Daucus carota) biennial
• buckhorn (Plantago lanceolata) perennial
• sheep sorrel (Rumex acetosella) perennial
• sour dock (Rumex crispus) perennial
• smooth dock (Rumex altissimus) perennial
• poison hemlock (Conium maculatum)
• multiflora rose (Rosa multiflora)
• wild sunflower (wild strain of Helianthus annus L.) annual
• puncture vine (Tribulus terrestris) annual
• teasel (Dipsacus) biennial
• shattercane (Sorghum bicolor) annual

In addition to the weeds listed in the Iowa Code 317, the Board of Supervisors declare the following weeds as noxious: Allaria petiolata (garlic mustard), Myriophyllum spicatum (Eurasian watermilfoil), Polygonum cuspidatum (Japanese bamboo) and Lythrum salicaria (purple loosestrife).

Noxious weeds from the Iowa Code 317 that are present in Story County shall be controlled before the following dates and as often thereafter as is necessary for control. Control is defined as prevention of the spread of noxious weeds by limiting the production of reproductive structures.

The list includes, but is not limited to;

• Group 1 by June 10 - Garlic mustard, leafy spurge, musk thistle, Eurasian watermilfoil, Japanese Bamboo, annual sunflower;
• Group 2 by June 15 - Canada thistle, purple loosestrife, teasel, poison hemlock.

For identification assistance, please visit:
http://www.weeds.iastate.edu/reference/noxiousimages.shtml

For a full copy of the current Iowa Weed Law, please visit:
http://www.weeds.iastate.edu/reference/weedlaw.htm

Brush Control

Story County’s IRVM program controls woody vegetation within the right-of-way, improving site distance around road signs and intersections, reducing snow traps, and improving conditions that might impede the maintenance of the right-of-way.

Story County’s Brush Management Policy was adopted on August 13, 2002 and reads as follows:

It is the policy of Story County that the vegetation of its roadsides to be preserved, planted, and maintained safe, visually attractive, and ecologically integrated and useful in many purposes (see Iowa Code section 314.22 for the full statement of the purpose of this policy).

The purpose of this policy is to control woody vegetation within Story County’s road right-of-way. To meet this purpose, the County has authority, in its discretion, to:

• Cut and/or spray any woody vegetation in the right-of-way which creates a situation that threatens the safety of the traveling public such as:

A. Snow traps and/or shading of the road that might occur

B. Site distance problems in relation to road signs or intersections

C. Conditions that impede the maintenance or improvements to the right-of-way

D. Width or height restrictions of vehicles or equipment using the roadway.

• Leave woody materials which have been cut or sprayed to decompose in the right of way.
• Burn the roadside vegetation to destroy small brush and stimulate desirable vegetation.

Utilizing these methods, the following guidelines will be implemented:

Along all county roads, dirt, gravel and paved, our normal procedure will be to clear the entire right of way width, utilizing level cuts as low as possible, with the following exceptions:

1. Tree and shrubs in house yards or residential acreages, whose bases are inside the right of way line by no more than five feet (5’), may remain, if desired, but limbs must be pruned back to the to the nearest lateral branch, so that they extend no further than eight feet (8’) into the right of way. A written notice of our intended work will be sent or delivered to these properties a minimum of seven (7) days prior to the commencement of our work. This notice will provide the landowner an opportunity to arrange for his/her own trimming and/or to request any larger material for firewood. (Landowner will be responsible for cutting into lengths and removing from ditch.)
2. Side trimming of limbs of trees will be done by pruning them back to no more than eight (8) feet from the right of way line when the tree base is actually outside the right of way.

The mechanical brush cutter will be used in rural non-residential areas with small scattered brush and trees where debris will be allowed to lay on slopes. Mechanically cut stumps, larger than eight (8) inches in diameter, as well as those larger trees that are cut totally with chain saws., will be cut flush to the ground, whenever possible. Large side branches will be trimmed to the main trunk or first lateral branch.

Brush control through cutting, spraying, and burning is an integrated approach to roadside vegetation management. Story County is committed to the wise use of herbicides on its roadsides and being consistent with employee and environmental safety and with regulations controlling the use of roadside application of pesticides in the state.

Equipment

The IRVM department has equipment available to assist with every aspect of native prairie establishment and management; from the back yard to the back forty. If you are interested in renting one of the following pieces of equipment, please contact the IRVM office at 515-382-7367.

Equipment available for rent:

• 6 foot, 8 foot and 10 foot native grass/forb seed drills
• 3-point broadcast seeder
• Cultipackers
• DiskHand-held seeder
• Spike-tooth harrow