- One of the most effective agronomic approaches of Intergrated Pest Management (IPM) is the “push-pull” system built on the concept of polyculture (agriculture using multiple crops in the same space) that protects maize, millet and sorghum from two devastating pests: the stem borer insect and the Striga weed.
- Push-pull entails mixing plants that repel insect pests (“push”) and planting diversionary trap plants around a crop perimeter which attract the pests away from the crop (“pull”).
- In the case of maize, millet and sorghum, the main cereal crop is intercropped with the forage legume Desmodium. Desmodium emits volatile chemicals that repel stem borer moths (“push”) and attracts a natural enemy of the moths, parasitic wasps (“pull”).
- In addition, Desmodium secretes chemicals from its roots that cause “suicidal” germination of Striga seeds before they can attach to the maize roots.
- To ensure further protection, farmers can plant a “trap crop,” such as Pennisetum purpureum (also known as Napier grass) around the edge of the field which attracts the moths pulling them away from the main crop.
- The system was developed in collaboration with the International Centre of Insect Physiology and Ecology (ICIPE) and the Kenyan Agricultural Research Institute (KARI) in Kenya and Rothamsted Research in the United Kingdom.
- As of 2010, 25,000 smallholders in East Africa are using push-pull systems. Adopting a push-pull system allows them not only to control pests but also to increase soil fertility, protect against erosion, reduce pesticide use and gain income from marketing Desmodium for animal fodder.
- In 2014, Greenpeace researchers interviewed three sets of farmers from Kitale and Mbita, Kenya: those practicing push-pull, those using pesticides, and those using neither approach.
- Although based on only a small number of interviews, average profitability per acre of maize per year was found to be 3 times higher for push-pull farmers than non-push-pull farmers, and this effect was even greater (up to 4 times more profitability) for women.
- Farmers also reported that maize yields often more than doubled compared to farmers that did not incorporate push-pull practices.
- In addition, push-pull farmers were also able to reduce their costs of labour and production.
Cotton Pest Control
- Pest management accounts for 25% to 45% of the costs of growing cotton in developing countries.
- Cotton accounts for nearly 25% of insecticide use worldwide.
- Cotton pests such as bollworm (Helicoverpa armigera) however can be controlled by biological control planting pest resistant varieties cultural control such as deep ploughing and low density planting the use of pheromones and bio-insecticides and even hand removal.
- A variety of crops can be intercropped with cotton to help recruit beneficial arthropods and natural enemies.
- Moths of the African bollworm prefer to lay eggs on crops such as pigeon pea, chickpea, maize, sorghum and sunflower, so these crops can be used as a distraction when planted in strips or around the field to reduce damage on cotton crops.
- The preference of bollworms to lay their eggs on maize means that it is often used as a ‘trap crop.’
- This preference is so strong that in some cases cotton plots remained almost clear of eggs when surrounded by a few rows of maize.
- Some successful examples can also be found in Asia.
- On cotton farms in the Xinjiang province of Eastern China, alfalfa has been planted around the field margins of 70,000ha of land.
- By cutting the alfalfa several times a season, beneficial insects are encouraged to move into the cotton areas, significantly reducing the number of Aphis gossypii, a damaging cotton pest in the region.
- Similarly in Eastern India, intercropping cotton with lucern, cowpea and groundnut enhanced natural enemy populations but cotton yields and overall profit of the system varied depending upon which crop was used.
- For example, cotton performed the worst when intercropped with sorghum and performed the best when planted with groundnut and chilli, highlighting the need to manage trade-offs between integrated pest management (IPM) concerns and system productivity and profitability.
Marigolds repel many species of insects. You can plant marigolds around tomatoes to inhibit the ugly green horn worms. These big insects can devour an entire tomato plant in one night. Plant marigolds around your entire vegetable garden to add bright color and keep the insect predators at bay.
- Herbs add flavor to foods, and they can also discourage harmful insects.
- Nasturtium and rosemary deter beetles that attack beans.
- Thyme repels the cabbage worm.
- Chives and garlic deter aphids.
- Oregano, like marigolds, is a good all-purpose plant for the organic gardener who wants to deter most insect pests.