Africa: five ways to get rid of pests without using chemicals

Pests can be, well, a pest. They infest crops and reduce yields, reducing overall agricultural production and food security. To deal with pests, such as mealybugs or spider mites, most farmers use chemical pesticides which can impact health, pollute water supplies through runoff, and, if pesticides are misused or overused, can actually kill plants.

Finding new methods to get rid of pests without requiring chemical inputs has increasingly become a priority for many farmers.

Today, Nourishing the Planet introduces five crop management methods that control pests without using chemical pesticides.

1. Crop rotation: Crop rotation involves alternating the species of crop that a farmer grows on his or her land each year. Rotating crops helps prevent pests from getting used to the type of plant that is being cultivated. Planting different species of crops each growing season also promotes soil fertility. Planting legumes, a plant that helps fertilize crops through nitrogen fixing bacteria that it has on its roots, and then planting crops that require high levels of nitrogen helps make sure that soil is healthy each growing season. And healthy soil helps protect against pests because an imbalance in plant nutrition increases a harvest's vulnerability to pests, according to Mans Lanting of ETC Foundation, a non- profit that focuses on linking agricultural sustainability to social development.

Crop rotation in action: Navdanya, a non-profit that promotes organic farming in northern India, is teaching farmers to use crop rotation methods instead of chemical pesticides. Navdanya has trained over 500,000 farmers in sustainable agriculture. In the city of Dehradun, a rice farmer named Thakur Das has been trained by Navdanya to grow rice, wheat, and corn using crop rotation methods. Das hasn't used chemical pesticides since joining Navdanya nine years ago and he claims that the switch from chemical pesticides has led to better soil health. "Most farmers use chemicals," but their "soil is totally dead," he notes.

2. Intercropping: Intercropping is the simultaneous cultivation of two or more crops on the same field. Intercropping works by attracting pests away from their host plant. Planting a variety of plant species on a field increases the distance between plants of the same species, making it harder for pests to target their main crop.

Intercropping in action: Farmers in Kenya have developed a "push-pull" intercropping method that cultivates plants that repel pests (pushing them away from the harvest) and ones that attract pests (pulling them away from the harvest).The farmers in Kenya grow maize with two types of cereals, one that helps push pests away from the maize, and another that pulls pest away from the maize. This method has helped to reduce the impact of the devastating maize stem borer and increase crop yield.

3. Crop diversity: In order to protect crops from pests, increasing the types of vegetables, plants, and fruits that are grown, makes each crop less susceptible to pests. "Pests and diseases thrive in monocultures because there is an abundance of food and few or no natural enemies to check their growth," explains sustainable agriculture expert Jules Pretty in State of the World 2011: Innovations that Nourish the Planet. To deal with this, farmers often rely on chemical pesticides, but Pretty points out that farm biodiversity is a more sustainable method of dealing with pests. "In the end, pesticide resistance inevitably develops within populations and spreads rapidly unless farmers are able to use new products right away," he notes.

Crop diversity in action: By focusing on crop diversity, farmers in Zimbabwe have created harvests that are more resilient to pests. Farmers have increased crop diversity by focusing on growing a broad range of indigenous crops such as mubovora (pumpkin) and ipwa (sweet reed).

4. Using pests to fight pests: Integrating predatory insects into a farm, such as ladybugs or predatory mites, can help kill off pests. Jules Pretty found that farms that provide habitats for pest predators have averaged a 79 percent increase in crop yields over previous agricultural systems that did not use pests to fight pests.

Fighting pests with pests in action: In the Nakhon Ratchasima province of Thailand, farmers use tiny wasps to help kill mealybugs that were destroying Thailand's multibillion dollar cassava industry. And in Florida, farmers are growing plants that attract wasps that lay their eggs in the larvae of harmful pests, which prevents those pests from reproducing.

5. Organic pesticides: Organic pesticides are not only healthier for people and the environment but they allow farmers and producers to make the most out of their resources by turning agricultural outputs into natural pesticides.

Organic pesticides in action: Home gardeners in Nepal apply zhol mol, an organic liquid pesticide made of neem leaves, timur, garlic, livestock urine, and water, to their vegetables and fruits. Similarly, farmers in India use neem trees as a natural pesticide. Neem trees, which can also be found in the Sahara Desert and Florida, can repel pests such as spider mites and cutworms.