Invasive species control, such as the control of thorny rose or giant balsam, is a concrete way to influence local nature. It improves the biodiversity of the area and can attract villagers of all ages. Cooperation increases cohesion and makes the village cleaner.
What are invasive species and why should they be controlled?
An alien species is an organism that has moved to a new area as a result of human activity, whether intentional or unintentional. Usually, species that have moved to a new area adapt poorly and do not cause any harm. Sometimes, however, an organism may thrive so well that its population grows too large and begins to crowd out other species. Such species are called invasive alien species.
Invasive species are controlled because they cause significant harm not only to nature but also to human health. Invasive species reduce biodiversity because they crowd out native species due to their superior competitiveness. Some species, such as giant hogweed, pose a health risk to humans by causing allergy and skin symptoms. Plants that are rampant, especially along roadsides, can also be a safety risk to traffic due to reduced visibility. Invasive species may also spread diseases. In addition to health damage, people have to suffer from aesthetic damage, for example when lakes and beaches are overgrown with flourishing vegetation.
Invasive species also harm people's lives from an economic perspective. Their control costs municipalities a lot, although there is no research data on the exact amounts yet. Estimates of the costs to Finnish society run into hundreds of millions of euros per year. Invasive species cause considerable economic losses, for example, to agriculture, forestry and fisheries. For example, growths of lupine and giant balsam can cause significant harm to forest regeneration by suffocating tree seedlings. It is therefore important to control invasive species, for example, by volunteer efforts.
Lupine
The common lupine is an example of a species that has adapted very well to Finnish conditions. It was originally introduced to Finland as an ornamental and fodder plant in the 19th century. The common lupine is an efficient spreader, and its seeds remain viable for a long time. Therefore, its eradication requires long-term persistence.
In addition to its efficient spreading ability, the common lupine also has a competitive advantage because it has the ability to bind atmospheric nitrogen. In other words, it practically fertilizes itself. The habitat gradually becomes more fertile, and the species of barren places and the insects that depend on them no longer thrive in the area. The common lupine also harms other plants by shading them. In addition, it secretes toxic lupanin, which weakens the reproductive ability of bumblebees. The common lupine therefore has a negative effect on biodiversity. The plant also causes harm to humans, for example by making reforestation more difficult when the common lupine suffocates tree seedlings.
Larger clumps of lupine are destroyed by mowing before the seeds have matured. This should be done 2–4 times during the growing season. The first mowing is done in early summer at the best flowering time before the seed pods have had time to form. If the seeds have already matured, mowing should not be done to prevent the seeds from spreading. Mowing debris should be collected and disposed of carefully according to the instructions of the municipality/waste company. Alternatively, it can also be composted or raked into a pile to rot. Covering the pile with a tarpaulin can ensure that the plants do not continue to grow. Instead of mowing, small clumps should be dug up individually with their roots. The rhizome can be composted after drying. If the plants have had time to form seeds, the inflorescences and other plant debris should be disposed of by placing them in a double garbage bag with combustible mixed waste.
Read more about the handsome lupine (opens in new window)
Giant balm
Giant balsam was first introduced to Finland in the late 19th century. It reproduces very efficiently through its seeds. One individual can produce up to 4,000 seeds, which it throws into its surroundings several meters away. The seeds remain viable in the soil for only a couple of years, which is why giant balsam is an easily destroyed plant.
Giant balsam competes with native species for space, light and nutrients. It attracts pollinators with its large flowers, which in turn has a negative impact on pollination of other species. The decline in other species also means fewer insect species that depend on them. Therefore, the spread of giant balsam weakens biodiversity. Like lupine, giant balsam also hinders forest regeneration by smothering tree seedlings. The plant is also associated with increased erosion, i.e., the wearing away of the soil surface, because the delicate root system of giant balsam does not bind the soil properly.
Giant balsam is controlled by mowing or weeding 2–3 times during the growing season. It is advisable to take action right away in early summer before flowering and seed ripening. Small growths can be weeded one plant at a time, but larger ones are more sensible to mow. Mow debris should be collected and disposed of according to the instructions of the municipality/waste company. Alternatively, the area can also be used for grazing, for example, by sheep. If the giant balsam has already produced seeds, the plants are removed from the ground and placed in a bag, top first. When the seeds are in the bag and cannot spread, the stem can be cut off. Giant balsam is easy to weed because its root system easily comes out of the ground, and no special protective equipment is needed. For this reason, controlling giant balsam is particularly well suited to be carried out as a volunteer project.
Read more about giant balsams (opens in new window)
Kurtrose
In Finland, the dwarf rose began to spread in the early 20th century. It escaped from yards and gardens into the wild, which is why most of the dwarf rose's growing areas are still located in urban areas and sparsely populated areas. The species reproduces both from seeds and vegetatively, for example from pieces of rhizome. The dwarf rose spreads as widely as the soil quality allows using its underground stems. The species is also very well adapted to water propagation.
Due to its efficient spread, the common seagrass can turn open sandy beaches into impenetrable thickets. In doing so, it displaces the original coastal species with other plants and insects. The common seagrass therefore reduces biodiversity. The common seagrass can also cause significant changes in the nutrient balance of the soil and the structure of microbial communities. In addition, recreational use of beaches suffers due to overgrowth.
Eradicating the rose bush requires persistence, as it is usually not successful the first time. Monitoring and aftercare should be carried out in the treated area in the coming years until the species has been eradicated. The first method of eradication is removal by rooting. The smallest specimens can be pulled up by hand, but tools are needed with larger specimens. The rose bush is cut down to the base with pruning shears or a clearing saw, after which an attempt is made to remove the rhizome as a whole. Pesticide waste must be collected and disposed of according to the instructions of the municipality/waste company. Another option is thinning. In this method, the rose bush is cut into stakes approximately 20–30 cm high, and the shoots growing on them are plucked off by hand at least 1–2 times a summer for a couple of years. The third method is covering. The rose bush is cut down and covered with a tarpaulin fixed to the ground. The tarpaulin is left in place for 2–3 years.
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Giant pipes
The giant tuberose group includes three species: Caucasian, Persian and Armenian giant tubes. Giant tubes were originally introduced to Finland as garden plants because of their large size and showy inflorescences. This alien species is very tolerant of northern conditions, which is why it has spread almost throughout the country. Giant tuberose reproduces by seeds. One individual can produce about 20,000 seeds, which remain viable in the soil for several years. For this reason, one application is often not enough to eradicate the plant, but control must be continued for several years.
Giant hogweed grows in a wide variety of habitats, such as fields, forests and beaches. They can form large, dense stands that cover everything else. Giant hogweed therefore reduces biodiversity and makes the landscape one-sided. People also suffer from giant hogweed, which causes allergies and skin symptoms, and can prevent recreational use of the area, such as fishing and outdoor activities. A giant hogweed that has taken over a plot of land also reduces the value of the property and the land.
It is a good idea to start destroying giant pipes in early May, when the plants are still small. Individual specimens can be controlled by cutting off the main root with a spade at a depth of 10–20 cm or by digging the root completely out of the ground. First-year seedlings with thin roots can be removed by hand weeding. Giant pipes can also be mowed, but this is safest to do when the vegetation is low. After mowing, the smaller vegetation can be covered with thick, opaque plastic. Covering will wither the plants and prevent new seeds from germinating. Care must be taken when disposing of plant waste and soil containing giant pipes. Non-reproductive parts of the plant, such as leaves, can be composted, but seeds and inflorescences containing them must be disposed of according to the instructions of the municipality/waste company. Large infestations can be destroyed with pesticides. This should be done in early summer when the plants are small. However, pesticides should not be used near water bodies or children's playgrounds, and it is advisable that the substance is biodegradable and environmentally friendly.
Read more about giant pipes (opens in new window)
Control of invasive species in our area
Jalasjärvi
On June 16, 2025, the city of Kurikka will bring waste pallets for invasive species to the front yard of the city's technical department warehouse at Keskustie 56. Non-native species waste can be taken to the pallets free of charge. Plant material must be tightly packed in a double garbage bag. The Kurikka Nature Association, in cooperation with the city, will deliver waste bags to the Jalasjärvi Library, where you can freely pick them up.
Small quantities of non-native species can be placed tightly packed in a plastic bag in a household waste container. A maximum of 2 m³ of non-native species waste can be delivered to a waste station, where it will be accepted for a fee. Larger quantities must be taken to a waste management center, where the fee is determined according to the price list.
Ilmajoki
In Ilmajoki, the city's employees are involved in the management of green areas and are responsible for the control of invasive species. For example, municipal employees remove giant balsam and tuberose when they see them. The municipality has also participated in invasive species efforts, for example by organizing waste management.
Seinäjoki
The city of Seinäjoki is combating invasive species by participating in the nationwide solo help campaign. The aim is for city residents to go and weed out lupine and giant balsam at the solo help sites themselves. The city has brought a mailbox to these points with instructions for weeding, as well as garbage bags and rubber gloves. The location of the solo help sites can be checked From the website of the city of Seinäjoki (opens in a new window).
The South Ostrobothnia ELY Centre eradicates alien species, such as lupine, giant balsam and dog rose, from its area of responsibility. The ELY Centre also provides information to citizens about the harm, spread and identification of alien species.