Malawi has an agro-based economy with over 85% of the rural population engaged in rain-fed subsistence farming. Due to the effects of climate change, the country is prone to natural hazards such as floods, droughts and pro-longed dry spells triggering pest and disease occurrences in farmers’ fields. This forces the majority of the farmers to use chemical methods of pest and disease control which may be harmful to the environment.
My innovation seeks to enhance natural pest and disease control methods among smallholder farmers in Salima District, Malawi. I am a 35-year-old environmental and economic sustainability advocate in agriculture. I have a Master of Science in Sustainable Agriculture and Rural Development from the University College Dublin (UCD) in Ireland (2015). I run an integrated crop and livestock farm where I use natural pest and disease control methods on crops.
Through participation in the IUPAC International Congress and the Next Generation Agri Summit, I will engage in public awareness and technology transfer of natural pest and disease control methods among rural smallholder farmers around my farm. The farm will act as a ‘model’ for the surrounding 5 villages which have over 3000 smallholders. These farmers mostly use chemicals to control pests and diseases. Upon participatory learning at the farm it is envisaged that 500 smallholder farmers will try out and adopt natural pest and disease control methods in their own farms each rainy season. In the long run we hope to scale out to a wider geographical reach and contribute to policy change.
What is natural pest and disease control?
This innovation will make smallholder farmers around my farm appreciate the fact that pests and diseases are part of the natural environmental system. In this system there is a balance between predators and pests. This is nature’s way of controlling populations. The creatures that we call pests and the organisms that cause disease only become ‘pest and diseases’ when their activities start to damage crops and affect yields. If the natural environmental system is unbalanced then one population can become dominant because it is not being preyed upon. The aim of natural control is to restore a balance between pest and predator and to keep pests and diseases down to an acceptable level. The aim is not to eradicate them altogether, as they also have a role to play in the natural system. Once a pest or disease has started to attack a crop, the damage cannot be repaired and control becomes increasingly difficult. The farmers will be taught techniques that avoid or prevent pest and disease attack in the first place.
Why is natural control preferable to chemical control?
Natural pest control methods are preferable to chemical control methods for the following reasons:
1. Cost: Using natural pest and disease control is often cheaper than applying chemical pesticides because natural methods do not require buying expensive materials from the outside. Products and materials which are already in the home and around the farm are most often used.
2. Safety for people: There is much concern over the dangers of chemical products. They may be misused because the instructions are not written in the language spoken by the person using the product. There have been reports of people suffering from severe skin rashes and headaches as a result of using chemical pesticides. There are an estimated one million cases of poisoning by pesticides each year around the world and many of these are in developing countries such as Malawi where chemical pesticides, which are banned in Europe or the USA, are still available
3. Safety for the environment: Pests are often controlled with man-made chemicals which can have harmful effects, for example: (i) artificial chemicals kill useful insects which eat pests (ii) artificial chemicals can stay in the environment and in the bodies of animals causing problems for many years (iii) insect pests can very quickly, over a few breeding cycles, become resistant to artificial products and can no longer be controlled.
Natural pest and disease control methods: Knowing the problem
Before taking action to control pests and diseases it is very important to make sure that the problem is correctly identified. Only then can you hope to succeed. Knowledge of pests and diseases will help you to decide whether the problem is caused by a pest, a disease, a mineral deficiency in the soil or an environmental factor. A good identification book may help with this. Proper identification should be the first step in controlling the problem and, more importantly, in preventing it from happening again. At the model farm the following natural pest and disease control practices are currently taking place. These will be imparted to the surrounding communities.
Maintaining a healthy soil: A soil managed using organic methods will give plants a balanced food supply. Plants which are fed well, like people, will be much more be resistant to pests and diseases.
Planting resistant varieties and utilizing genetic diversity: Within a single crop there can be many differences in terms of resistance to diseases. For instance, traditional varieties have been grown and selected over many centuries to meet the requirements of the farmer and are still saved locally.
Crop rotation: Avoidgrowing the same crops in the same site year after year to avoid a buildup of pests and diseases in the soil which may be transferred from one cropping season to the next.
Good hygiene: If infected plant material, live or dead, is left lying around, pests and diseases can be passed on to future crops. Debris should be cleared up and disposed of.
Soil tillage and Soil PH: Many pests spend part of their lives as larvae or pupae in the soil. Ploughing or digging when the soil is dry can reveal the pest and they will dry out and die in the sun, or they can be picked off the ground by hand or birds or other predators. The pH (acidity or alkalinity) of a soil can affect some diseases. Changing the pH can reduce the problem. For example, potato scab is less severe in more acid (pH below 7) soils. A layer of grass mowings added to the bottom of the potato trenches at planting time will make the soil more acidic and reduce the disease.
Companion planting: Companion planting means growing certain plants to protect other plants from pests or diseases. This may be because the pest is deterred by the companion plant, or because it is attracted to the companion plant rather than the crop. For example, many pests avoid garlic, so this can be used very effectively for companion planting with most crops.
Plants to attract predators and parasites: Similar to companion planting, which seeks to deter pests from the main crop, attractant plants can be grown to attract predatory insects.
Areas of natural habitat: Bushes and trees are a home for many useful insects and birds. Areas of natural habitat can be left around the edges of fields where crops are grown. If these areas are destroyed then there is likely to be an imbalance between the populations of predator and pest.
Specific plants to attract beneficial insects: There are many plants that can be grown to attract natural predators and parasites which will help to keep down pests and diseases. Flowers such as marigolds (Tagetes), mint (Mentha), sunflower (Helianthus annus), sunhemp (Crotalaria juncea) as well as local legumes are useful attractant plants.
Barriers: Barriers are physical structures put in place to prevent a pest from reaching a plant. They keep pests away from a plant but do not kill them.
Pheromone traps: Pheromone is the sexual attractant produced by some female insects. If a trap is baited with this it will attract the male insects into the trap from which they cannot escape. Pheromone traps alone can reduce pest damage and also give an indication of pest populations.
Hand picking and squashing: In some cases, it may be possible to pick pests directly off the crops.
Biological control: This often involves introducing a creature or organism, which is known to be predatory, to an area with the aim that it will control the population of the pest.
Natural pesticides: If pests and diseases cannot be prevented or controlled by cultural and physical means, it may be necessary to use natural pesticides. Examples include a solution made from marigold using water and soap.
Brian Kachisa, Malawi