What are the best tricks in agriculture

Voles (water voles) in the garden

Voles can cause considerable damage to fruit trees, soft fruit trees, ornamental trees, flower bulbs and vegetable crops. This information leaflet shows options for repelling and controlling voles in house and allotment gardens.

Appearance and way of life

The vole (Arvicola terrestris), also called water vole, occurs all over Europe. The head is blunt, the ears are small and almost completely hidden in the fur. The color of the fur ranges from brown-gray to red-brown, black is also found. The hairy tail is slightly shorter than half the body length, which is about 15 cm. As a natural settlement area, the vole prefers fresh, moist soils, ditches, meadows, light deciduous and mixed forests and grassy young cultures. They only come to the earth's surface to migrate and mate, rarely to eat. The vole does not hibernate. It therefore damages all year round. The female gives birth to two to four litters with two to five (rarely up to ten) cubs each from March to October. The animals of the first litter become sexually mature in the same year. The multiplication rate is at least 1:10, i.e. H. there are ten or more offspring per year. The burrows are usually inhabited by an animal, as the male only stays with the female for a very short time. The young voles also have to build a new burrow. This leads to a rapid spread of the pest.

damage

Voles damage a wide variety of plant species by gnawing and eating roots, rhizomes, tubers and bulbs. The sward can be destroyed by the burrowing activity on grassland or lawns. Weed the imperfections very quickly afterwards. In the case of trees, mainly younger ones are at risk, e.g. B. Apple trees on weakly growing bases. The damage occurs mostly unnoticed during the winter. They are only discovered when trees or bushes sprout weakly or not at all in spring. The plants are no longer firmly in the ground, can be easily pulled out and the main root looks like it has been sharpened.

Infestation detection

Pile of earth

The piles of earth lie next to the passages and, in contrast to those of the mole, are lower, more irregular in shape, the earth is finer and mostly mixed with plant debris. The mole pushes evenly formed, high heaps of earth without any plant residues. His walk ends in the middle of a pile of earth.

Corridors

The vole passages are closed; They are only open by the water or when there are youngsters under construction. Above-ground walkways (changeover) are not available. The underground passages generally run at a depth of 5 cm, in places up to 1 m parallel to the earth's surface. The total length is on average 50 m, in individual cases up to 100 m and more. They are high oval and always over 5 cm wide. The roots on the walls of the corridor have been neatly eaten away. The vole creates storage chambers in which they can store roots, bulbs, tubers, etc. stores.

Defense

Among the most important natural enemies the vole includes the weasel species, especially the mouse weasel. But also fox, polecat, martens and cats as well as owls (especially the barn owl) and birds of prey (e.g. the common buzzard) hunt the vole. To support the natural enemies, perches can be set up as a hide for birds of prey, entry holes can be created in barns for owls and heaps of stones can be offered as shelter for weasels.

The plots intended for the replanting of valuable crops are to be made as free of voles as possible in late autumn by catching, cultivating the soil and removing forage plants. The recommended planting date is spring, as the voles otherwise concentrate on the young trees planted in autumn.

Trees can be safely protected with a wire basket. A basket is formed with wire mesh (mesh size approx. 15 mm) in which the tree is planted. The wire must be carefully hooked onto the folded seams. After the earth has been filled in, it is bent against the trunk, but not fastened there. It can then be covered with an approx. 5 cm thick layer of earth. The same can be done with onions or tubers. Specialist shops also have special wire pots or baskets that offer a certain amount of protection against vole damage.

It is often recommended to pour strongly smelling substances (e.g. fish brine) in the aisles, or to grow milkweed, garlic and imperial crowns. Apart from a short-term expulsion, however, nothing is achieved. The use of rattle mills, wind turbines, opened bottles, knocking sound vibrators or devices generating ultrasound has also proven to be ineffective.

Combat

The best periods for control are late autumn, when the ground is open, and early spring, before the voles begin to reproduce. Measures taken during the summer months are less effective. Since young voles colonize new areas during the entire vegetation period, not only individual pieces of land, but as much as possible all areas of an allotment garden or a residential area should be included in the control. Before any control measure, an infestation investigation is necessary, also to exclude control of the mole protected by the Federal Species Protection Ordinance.

At the beginning of a combat action, the rooting test takes place. In addition to the earth ejections, the soil should be scanned on circular paths with the vole stick (Fig. 1). If a passage is hit, the stick sinks in abruptly. At this point the passage is exposed with the spade over a length of 20-30 cm and the two openings are carefully cleaned of loose earth with a digging knife. A carrot is placed in both passageways. An inhabited corridor is soon burrowed again by the vole, especially in cool weather, and the carrot gnawed at it. If a mole lives in the open duct system, it will subvert the open area. The scrambling test is also necessary to check success (except when catching a trap). To make it easier to find the sample locations, it is best to mark them with a wooden stick or something similar.

Falling

There are different types of traps. Some have to be baited before use; they are partly catchy on one side, partly on both sides. A frequently used type of trap is the "Bavarian wire trap" (Fig. 2 and 3). But also tilting bow traps, tube traps or the Sugan vole trap from Neudorff (Fig. 4) show good catches.

Setting traps

The troubled passage is carefully exposed again, cleaned of loose earth and z. B. the wire trap pushed into the aisle. It must be ensured that the large ring of the trap rests firmly against the passage wall. In order to give the trap a firm fit in the corridor, the clamping fields are placed under a turf and the end piece of the trap is pressed into it.

The procedure for the other types of trap is similar. They should fit into the aisle opening or be placed close to the aisle opening.

If baiting is possible, carrots, apples, potatoes or celery can be used as bait. The voles must not be deterred by external weather conditions. New traps should therefore only be exposed to the weather for some time. You should also rub your hands with earth (or wear gloves) before setting up the traps. Traps that can be caught on both sides are particularly recommended in loose soils because both sides are not tumbled at the same time.

A relatively new type of trap is the SuperCat vole trap. Compared to conventional traps, it is very easy to handle and also very catchy.

Fumigation

For this purpose, preparations with the active ingredient calcium carbide (e.g. Detia vole gas) can be used, which develop an unpleasant smelling gas when they come into contact with the damp soil. The gas mixture that is generated drives the voles away, but does not kill them.

In any case, it is important that the duct openings are tightly closed again immediately after the preparation has been applied. When using it, it is essential to follow the manufacturer's instructions for use exactly.

Feeding bait

In addition, food poisons based on zinc phosphide are available in stores. These are ready-made baits (e.g. Celaflor vole bait Arrex and Detia vole bait). In these baits, the active ingredient zinc phosphide is only released in the body of the vole. The introduction into the corridors is similar to that of the phosphine-evolving pellets. It is forbidden to lay it out in the open so that other animals - especially birds - are not endangered!

In times of abundant food supply, voles often do not take in enough poison, so that the bait then spoils. Occasionally it is also entered in the pantry. By the time it is eaten there, the active ingredient is often already broken down. Therefore, like the traps, bait should preferably be used in late autumn or early spring (if there is a lack of food).


Chamber of Agriculture North Rhine-Westphalia, Plant Protection Service
Nevinghoff 40, 48147 M√ľnster
 
The instructions for use stated on the packaging must be carefully observed.

Author: Andreas Vietmeier