Voles

Overview

Voles can be found in every state of the mainland U.S. and Canada.  There are over 23 species (Genus - Microtus in North America. Voles are frequently mistaken for shrews, field mice & deer mice. While similar, distinguishing features include longer, coarser hair, and a larger head size.

Vole Taxonomy & Behavior / Technical Sheet

Rozol Vole SLN 24c WA Label

Vole Map

Voles can often be found in wild and landscape environments with rock structures nearby.  Vole activity is more frequently visible during winter months and in the spring, immediately after snow melt.  Voles cause economic damage in many areas, some of the more important of which include:  Orchards, Commercial Nurseries, Christmas Tree Farms & Forestry Plantations.  Rozol^® Vole Bait is registered for use in these usage segments in select states.

Damage

• Voles can cause extensive damage to orchards, ornamentals and tree plantings by gnawing on roots and on the bark of seedlings and mature trees (called girdling).

• Voles consume foliage, seeds, stems, bulbs and small roots, and girdle large roots, which disrupts the tree’s flow of nutrients and water. Voles can kill trees and smaller plantings, as well as cause foliage and production loss, and the onset of root disease by exposing vulnerable tissue and creating air pockets.

• Because it occurs underground, root damage is harder to detect. By the time weak, unhealthy trees are noticed,root damage is often extensive. Trees experiencing root damage from voles exhibit stunting and foliage reduction,resulting in production losses.

• In a 1987 study¹ on McIntosh orchards in New York, vole densities of up to 400 per acre led to major production losses. During the second year, the highest vole population reduced fruit yield by 65.5% and increased undersized fruit from 3.1 to 57.5% – reducing income by $2,745 per acre.

• Pine voles also build extensive runway and tunnel systems. In the Willamette Valley, voles inflicted varying degrees of damage on 40-50% of grass seed acreage(a $300 million a year crop),² leading to stand loss as high as 60% in 2005.³

• Meadow Voles (Microtus pensylvanicus) can cause unsightly runway damage to lawns & golf courses.

¹ Effects of Differential Pine Vole Populations on Growth and Yield of McIntosh Apple Trees, Proc.EasternWildlife Damage Control Conference, 1987. Richmond, M.E., C.G. Forshey, L.A. Mahoffy and P.N. Miller.

² Dave Pehling & Todd Murray (WSU Snohomish Co.)

³ Mark Mellbye Field Crop OSU Ext.Agent, Linn County, and Bruce Coblenz Prof.OSU Dept. of Fisheries &Wildlife, Bob Rost OSU Gardening Expert – OSU News 06-28-05

See entire label. It is the responsibility of the user to read and follow all label directions.

Specimen Label / MSDS

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California Voles

Overview

Six species of voles of the genus Microtus occur in California. The California vole (Microtus californicus) is the most widespread vole in the state, found along nearly the entire length of the coast range, and is responsible for the majority of damage to vegetables.

These voles are grizzled brownish with scattered black hairs on their backs; and gray hairs below, with hairs often white-tipped. They possess a relatively long, two-colored tail and pale feet, and can reach 5 to 8 inches in length from head to tail. They typically weigh from 1 1/2–3 1/2 oz (42–100 g).

Voles are prolific breeders with females maturing in 5 to 6 weeks and having 5-10 litters per year. Litter size ranges from three to six. However, voles seldom live past a year.

Damage & Disease Transmission to
Artichokes / Vegetables

Voles are feed on a variety of grasses, herbaceous plants, bulbs, and tubers. They usually consume bark and roots of trees, only in the fall or winter, when other food sources are less available. In California, they cause notable damage on the following vegetables: artichoke, beet, Brussels sprouts, cabbage, carrot, cauliflower, celery, lettuce, turnip, sweet potato, spinach, and tomato.

California voles are known carriers of the hantavirus and probable carriers of other diseases as well. Vegetable growers are concerned that California voles, along with slugs & snails, can also transmit, through gnawing and saliva, e. coli. and other bacteria.

Rozol^® Pellets are registered for use only within the state of California for the control of California voles (Microtus californicus) in artichoke fields. When used for this purpose, Rozol Pellets are a Restricted-Use Product, and may be sold and used only by Certified Applicators, or persons under their direct supervision, and only for uses covered by the Certified Applicator’s certificate.

Helpful Application Tips

Use Rozol pellets as an alternative to Chlorophacinone treated artichoke bracts only during the period from October through March if artichoke bracts are not available. Place about 3 to 5 grams of bait (approximately 1 level teaspoon) per artichoke plant, on bare ground in infested areas. Apply bait near vole burrow openings or runways located between artichoke plants. Be careful to place bait so that it does not directly contact any part of the artichoke plant. If necessary, make second and third applications at 21 day intervals. Do not exceed three applications made at minimum 21 day intervals. Do not apply this product by any method not specified on this label. Do not broadcast bait.

See entire label. It is the responsibility of the user to read and follow all label directions.

Sources: Paraphrased from UC-Davis Pest Notes: Authors: T. P. Salmon, Wildlife, Fish, and Conservation Biology, UC Davis; and W. P. Gorenzel, Wildlife, Fish, and Conservation Biology, UC Davis. Editor: B. Ohlendorf.

Specimen Label / MSDS

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Mountain Beavers

Overview

Mountain Beavers, also known as “boomers” can be found in North America. The two main ranges of mountain beavers are from Merritt, British Columbia to Rio Dell, California and from Mt. Shasta, California to western Nevada. Presently, they may only be controlled using baits on the western portion of the Cascade Range in Oregon, Washington. There is only one known Genus, species in North America Aplodontia rufa, with two sub species.

Mountain beavers are primarily dark brown, and do not have the traditional flat beaver tail. They have strong incisors. Their head is flat and wide and their nose is slightly arched. The body is covered with coarse, dull fur. Underneath the fur is a sparse covering of guard hair, which is dark red of grayish brown in color. They have short limbs and their total length is 12 –19 inches (30 - 47 cm). For perspective, they are most similar to woodchucks and porcupines. (Carraway, 1993).

Mountain beavers are not as social as other rodent preferring to live in solitude. They vocalize in the form of whistles and “booming” sounds, hence the nickname. Young are active foraging within 6 – 8 weeks. Females do not typically breed until their second ovulation, with one gestation per year, and lifespan is typically 5-6 years.

Damage

Mountain beavers have damaged an estimated 300,000 acres (120,000 ha) of commercial coniferous tree species in western Washington and Oregon. Much of the affected land has the potential to produce timber values of over $10,000 an acre*. The damage period extends to about 20 years after planting. Mountain Beavers cause economic damage by clipping and topping off new seedlings, girdling trees & roots, leading to stunted growth and production losses in forestry plantations. This is of particular concern in areas undergoing reforestation, and also includes recreational land. In combination with “Special Local Needs” 24 (c) labels in Oregon & Washington, Rozol^® Pellets may be used as part of a control program. Check with your local Department of Agricultural for the latest information, as labels change frequently.

Helpful Application Tips

Do not tear open the packets of bait. Place one unopened packet of bait inside two feeder holes or active runways of each active mountain beaver burrow system, (i.e., one packet per hole or runway; two packets per burrow system). Insert bait packets at least 12 inches into hole or runway.

Applications made between October and February have been found to be the most effective at reducing damage to tree seedlings planted in late winter or early spring. Baiting from mid-May to mid-September, when juveniles mountain beavers are present, is not permitted due to concerns with the secondary poisoning of non-target animals. See entire label.

*Source: Carraway, L.N.; Vects, B.J. (1993, April 23). "Aplodontia rufa." The American Society of
Mammaolgists, 431.

Rozol Pellets Specimen Label / MSDS

Rozol Mountain Beaver SLN 24(c) OR Label

Rozol Mountain Beaver SLN 24(c) WA Label

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