As if all the pests in the world were not enough, cultivators have been forced to time and again acknowledge the fact that certain four-legged creatures are set to wreak havoc in our backyards and orchards! They are voles!
These relatively huge creatures, i.e. if you compare them with the measly crop pests that you usually encounter; can be a source of great nuisance to trees in the orchards almost to the extent of driving you up the wall.
A vole is a small rodent resembling a mouse but with a stouter body, a shorter, hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars – high-crowned and with angular cusps instead of low-crowned and with rounded cusps. There are approximately 155 speciesof voles. They are sometimes known as meadow mice or field mice in North America.
The two main types of voles that cause damage are woodland voles also known as pine voles and meadow voles. The woodland vole (Microtus pinetorum) is a small vole found in eastern North America . The woodland vole lives throughout the eastern United States, ranging as far as Nebraska, Kansas, Oklahoma, and Texas. They inhabit deciduous forests, dry fields, and apple orchards. In addition, apple orchards are a favorite habitat. Woodland voles tend to be sparsely distributed in natural habitats; densities usually are highest in orchards during fall. The average population density is up to 2.4 per hectare. Recorded densities range up to 15 per hectare, although they are likely to reach higher numbers in orchards. The root systems of trees are an important food source for voles and thus tree spacing affects the density of vole populations. Woodland voles amount to high economic losses owing to the damage they cause to apple orchards. Vole feeding costs apple growers annual losses of nearly $50 million.
The meadow vole (Microtus pennsylvanicus), sometimes called the field mouse or meadow mouse, is found across Canada and the northern US. Its range extends further south along the Atlantic coast. Meadow voles are most commonly found in grasslands, preferring moister areas, but are also found in wooded areas. Meadow voles are active year-round and day or night, with no clear 24-hour rhythm in many areas. Meadow voles eat most available species of grasses, sedges, and forbs, including many agricultural plant species. Leaves, flowers, and fruits of forbs are also typical components of their summer diet. Fungi have also been reported in meadow vole diets. They occasionally consume insects and snails, and occasionally scavenge on animal remains. Meadow voles may damage woody vegetation by girdling when population density is high. In winter, meadow voles consume green basal portions of grass plants, often hidden under snow. Other winter diet components include seeds, roots, and bulbs. They occasionally strip the bark from woody plants. Seeds and tubers are stored in nests and burrows.
Voles in general are a rodent species capable of causing a lot of damage because of their ability to multiply quickly in response to abundant food. Cultivated crops, orchards, and lawns all over often feel the brunt of this damage. The damage may be particularly severe in areas experiencing drought conditions. Population levels generally peak every 2 to 5 years, but these cycles are not predictable. These populations’ shifts may result in densities ranging from a few to several hundred voles per acre. In rare cases, vole populations may become extremely dense. During the early 1900s, vole populations were estimated at 25,000 per acre in some areas of Nevada.
Voles may cause extensive damage to fruit trees and orchards as a result of girdling seedlings and trees damaging roots. They will readily thrive on small plants. This girdling can easily kill young plants and is not healthy for trees or other shrubs. Voles will often eat succulent root systems and will burrow under plants or ground cover and eat away until the plant is dead. Bulbs in the ground are another favorite target for voles; their excellent burrowing and tunneling skills give them access to sensitive areas without clear or early warning. Voles feed on both the roots and stem system and the vegetation of plants, as well as fruits, seeds, bark, subterranean fungus and insects.. Vole damage can kill a tree outright, allow diseases to enter, or weaken the tree, resulting in decreased fruit production for the life of the tree. Damage occurs primarily during winter when other types of food are scarce. Since voles burrow in the snow, they may damage tree trunks as high as snow accumulates. Young trees are especially susceptible to attack. Damage from pine voles is harder to detect because it occurs underground as they consume small roots, girdle large roots and eat bark from the base of trees. By the time orchardists note weak, unhealthy trees, the damage is already extensive.
The most easily identified sign of meadow vole presence is a system of surface runways in the grass. Pine voles do not use surface runways, so their presence is much harder to detect. In apple orchards, tiny, elongated tooth marks on apples on the ground are signs of both meadow voles and pine voles. Probing the area under the tree with your fingers may help determine if there are vole runs close to the surface.
The estimated annual loss from vole damage to apple growers in North Carolina is $2.5 million!
Currently used methods of dealing with these annoying rodents are the use of extremely toxic and potentially dangerous rodenticides like Zinc phosphide, chlorophacinone and diphacinone. Zinc phosphide is acutely toxic to all vertebrates and therefore presents risks to non target wildlife in the orchard as well as safety risks to people. Chlorophacinone and diphacinone are much more toxic to rodents than to other mammals or birds but we still cannot eliminate the risk they pose to the non-target species.
Thus the time has come for us to let go of the past and move forward. The best way to achieve this is to stop taking undue risks posed by the use of toxic rodenticides and opt for a better and greener solution which will be non-toxic and harmless to the non-target species. C- Tech Corporation can provide with desirable and viable solution for the existing vole problem. Rodrepel™ a non-toxic, non-hazardous and environment friendly product repels rodents like voles. The product works on the mechanism of repellence and does not kill the target or non-target species. Thus it will be effective in keeping the voles away from our precious crops. The product can be incorporated in agriculture films, irrigation pipes, mulches etc. to protect the crops from the voles.