FOR a long time, invasive plant species have caused a splitting headache to communities due to their negative effects on the environment.

As a result, their control has drawn much attention from different stakeholders, like the Government, environmentalists, local leadership and different communities depending on the type of plant found in the area.

Invasive plant species can be indigenous, or exotic.

Although some exotic species have no local names, when such plants find a favourable environment, they grow and have a larger coverage in a given area of land, for example, grazing land.

Some of the invasive species spread very fast due to their growth habit and create some challenges in controlling them like the Kariba weed/water fern salvinia molesta and water hyacinth eichhornia crassipes which once got established and spread fast in Lake Kariba and other water bodies in different parts of the country.

A number of challenges are experienced during the growth, and spreading of these invasive aquatic plants: boats have difficulties moving, irrigation pipes are choked, fish production is reduced and livestock drown as they get attracted to the green plants seen in the water bodies.

Different ways have been tried to control the plants, but most of the control methods employed proved fruitless until the use of biological methods in this case the use of black weevils gave better results.

Invasive plants like Chinese sickle pod — senna obtusifolia /Isizambane, lantana camara —ubuhobe/mabarapati are common in different parts of the country. Some of the invasive plant species like Chinese sickle pod, are not eaten by most herbivores including domestic animals and this has given them the opportunity to sprout in communities. This has caused some community members to abandon their fields when the plant gets established.

The plant has been scientifically proven to exude chemicals which inhibit growth of other plant species and has other negative effects on certain parts of the body of an animal which might feed on them, for example, the liver.

Lantana camara’s (ubuhobe/mabarapati) negative effects on soil, livestock and human beings has been topical in different parts of the world. The invasive species causes irritation to animal skins with some even developing wounds.

It has also caused eye damages to both livestock and human beings.

The milk weed (asclepias syriaca) is one of the invasive plant species which have had a negative effect on the environment, and is common as weeds in most fields. While we appreciate findings by different researchers on how the invasive plant seeds managed to find their way into our country, some of the sources of origin are quite interesting.

For example, some seeds came as horse feed. They were imported with horses during the war. The continuous supply of horse feed during war times brought a variety of seeds of invasive plant species, species like lantana camara.

Their growth was promoted as they were considered to be beautiful flowers, and this was before its negative effects were recognised.

Depending on the invasive plant species to be controlled, various methods have been employed to reduce their spreading.

For most invasive species, the ideal stages of completely destroying the plants are when the seeds of the plant have not yet matured, and when the roots can be completely eradicated, that is, when the soil is moist.

Burning of removed plants has also been used for complete removal, of for example, lantana camara. Like in other countries, the Government has also enacted some laws supporting the eradication of such environmentally unfriendly plants.

While efforts of removing these problematic plants are strongly recommended, and supported, the big question is, like any other plants — after their harvesting from communities, can’t they be processed to something which can be of economic or social benefit to human beings like compost?

While we are used to the usual methods of removal, and dumping or sometimes burning of these invasive plants, it is sometimes ideal to think out of the box regarding the removal and disposal of these unwanted plants from communities.

Like other plants, when harvested at the correct time that is before the maturity of seeds or when the roots are completely removed — can’t a compost making project be started and promoted in communities dominated with such plant species?

While appreciating that researches have to be undertaken to determine the effectiveness of the compost manure produced from such plants, action by different bacteria especially the thermophilic bacteria, that is, bacteria which promotes decomposing through high temperatures can give the best results in terms of breaking down the poisonous chemical composition of the decomposing invasive plant. Every year, some grants are offered by different project funders so that communities, especially rural ones can benefit, these grants will be targeting improving the environment.

Instead of collecting, and burning these invasive plants, a compost making project can be started. The initial stage of the project will be supporting the removal of the invasive plants, for example, the community can be engaged to uproot and collect the invasive plant species found within their communities and are paid according to the quantity harvested.

The harvested invasive plants, will form part of layers of the compost depending on the size of heaps formed. In this project, the aim will be of producing large quantities of compost manure which when well branded, and has proved to be beneficial in improving soil fertility can find a good market in agro shops, or gardeners in cities and towns. The profits realised from selling this organic fertiliser, can be ploughed back to the project to make it sustainable.

It is important that as communities, and as a country we always think of other approaches of eradicating invasive plant species for the improvement of our environment, protecting our livestock and improving the productivity of our soils.

Mahlabezulu Zulu is a conservationist who has worked for various wildlife research, and conservation organizations in Hwange National Parks, and Fuller Forestry in Victoria Falls.

He can be contacted on 00263(0)713269827/0776196171. Email [email protected]  or   [email protected]