Making your own pesticides as easy as ABC

Kenya National Museum Head of Ex-situ Conservation Dr. Patrick Muthoka, Scientist in Ex- situ Conservation Vivian Kathambi and Head of Botany Department Dr. Itambo Macomb show farmers on some of the plants that can be used for pesticides during the Farmers training at National Museum on organic pesticides and their effects on the environment. ON 25/05/16 PHOTO: JENIPHER WACHIE

Ask Joseph Wabwire how long he has been a farmer and he will proudly say he has been one since he became an adult.

Now 43, Wabwire and his three-acre arm in Busia County are inseparable. He can be considered a veteran in farming, but he feels one can never stop learning.

Wabwire was in Nairobi this week at a farmers’ training workshop on how to use pesticidal plants in farming as a better alternative to synthetic pesticides.

He has known the pain pests such as weevils and stock borers can bring by destroying crops, reducing yields and eventually, reigning free on the crops when they develop resistance to pesticides.

Wabwire says he grew tired of pests and synthetic pesticides and decided to look for an alternative. That is how he landed on pesticidal plants.

There are naturally occurring pesticides derived from plants, which he cultivates. One such plant is Tephrosia.  He has also taught other farmers in his area how to grow and use them.

Wabwire is onto something, having stumbled upon ages-old methods of dealing with the pest menace. Pests have always been a bother to farmers all over the world since agriculture began. Over time, farmers learnt effective methods on how to deal with them, and successfully implemented these methods for centuries.

It was not until the 1940s that synthetic pesticides were invented. They seemed godsend at the time, because they worked extremely fast and required little monitoring. However, the tide has been turning over the past decade, with people slowly realising the dangers that synthetic chemicals pose to their health and environment, in addition to not being cost-effective.

Better results

Different pesticidal plants work differently depending on the area they are found. Many of them work universally though. The problem has been that knowledge of what works is usually contained to a specific group of farmers in one area, and other farmers in another area may not be aware of it.

As Prof Steve R Belmain, an entomologist from the Natural Resources Institute at the University of Greenwich explained, that gap in communication has resulted in a lot of potential not being harnessed from plants.

Together with other scientists, Belmain has been carrying out research on hundreds of pesticidal plants and the best way to harness their natural properties so that they work just as well as, and in some cases, better than synthetic pesticides.

The farmers at the training workshop at the National Museums of Kenya where Nabwire was had been drawn from all over the country to learn about these methods, learning what has been discovered so far and also sharing knowledge among themselves.

The training has been dubbed Options (Optimisation of Pesticidal plants: Technology, Innovation, Outreach and Networks). Farmers at the workshop learnt that plants may look common as they occur in the wild, but that “the wild” is disappearing as bush lands turn into farmlands. The natural habitats for these plants are getting lost, so farmers are encouraged to plant them to promote their propagation.

While explaining this, Dr Itambo Malombe from the Botany Department at the National Museums of Kenya says out of the approximately 100 pesticidal plants in East Africa, 84 are found all over Kenya. Some of these include Tobacco, Bidens pilosa (black jack), Pyrethrum, Neem (Muarobaini), African violet tree, Fish bean, Lemon bush, Capsicum (chilli pepper), Tithonia diversifolia (Mexican sunflower or Mexican Marigold), bitter tomato, Euphorboia among others. To use pesticidal plants, Prof Belmain says one has to change their mindset. With synthetic pesticides, the pests die instantly but the effects are dire. Pesticidal plants work differently, such that the pests will die over a number of days or will be present but will not harm the plant as they are repelled from eating it. Pesticidal plants also require more work, but cost less as the farmer is encouraged to experiment, use what is available and is encouraged to grow most of these himself.

This change of mindset has worked for Nabwire. “I plant and prepare them myself,” he says. “It is just a matter of plucking the leaves, drying them, preparing the solution and spraying it onto the plants.”

The general rules on the use of pesticidal plants include never drying the plants in the sun but always under a shade in order to preserve the chemicals in them and then storing them in the dark. A typical solution would be prepared by grinding the plant to a fine powder, then mixing it in water.

Fatty chemicals

For this, the farmer is advised to use a little bit of soap as it helps to extract the fatty chemicals, spread the extract and help it stick to the plant. This mixture sits for 24 hours and should be sprayed in the evening, because when the sun comes up it starts breaking the compounds down naturally.

“All commercial synthetics are designed not to break down in this way but pesticidal plants don’t have those chemicals so natural chemicals will break down naturally,” says Dr. Belmain. The ratio of the pesticide to water should generally be between 1 to 10 per cent. Ten percent would be, for example, 1kg of plant material in a 10-litre bucket. One can use any kind of soap, even laundry water that has been used for washing clothes. To spray on harvested grain, one should make sure that the grain is dry enough.

With synthetic sprays, the farmer sprays once in about two weeks and does not have to check again, but with pesticidal plants, one has tobe more observant and monitor the insect problems, make the extract and keep re-applying if necessary, which may be slightly more often than with synthetic pesticides.

So far, there is no evidence showing that pests develop any resistance to pesticidal plants, because they work differently. Dr. Belmain explains that with synthetic pesticides, they usually have just one active ingredient that pests’ systems learn to override, but with pesticidal plants there are usually five or six active compounds working together, making it almost impossible for the pests to counter.

Pesticidal plants are also ideal for organic farming as they meet international regulations, being all-natural and are more sustainable for the environment. They usually also have multiple uses such as being a source of timber and food products.

According to Esther Kioko, an entomologist and senior research scientist at the National Museums of Kenya, majority of the synthetic pesticide chemicals face economic and ecological challenges worldwide, due to the health risks they pose and the damage that they do to the environment. The World Health Organisation reports that each year, three million workers in agriculture in the developing countries suffer pesticide poisoning, and about 18,000 of those affected die.

These pesticides remain in the foods. Others get into water bodies and fish and continue to become more concentrated as the food chain goes up. “Some chemicals in synthetic peticides mimic the hormones in our bodies such as the reproductive hormones, so the reprodutive system is affected,” says Dr Kioko.

Many of these synthetic pesticides have been banned all over the world, but some oare still widely available in Kenya. Farmers are advised to consult agricultural officers in their local areas before using synthetic pesticides, and even then, they should be a last resort, having tried all other methods.

For Nabwire, these are the best methods. He cannot wait to put the additional knowledge of more pesticidal plants to use on his own farm. “It is easier because I never have to buy them. They are just there, easily available and you just mix the quantity that you need at any time,” he says. “Not everyone grasps these new concepts but most have been responding positively because it is worth it.”