Application of Herbicides in Africa

I. Current Usage: Widely Disparate Adoption Rates with Overall Growth

• Ghana (55%), Nigeria (30-33%), and Ethiopia (30-33%) lead in adoption rates

• Kenya and Tanzania have an adoption rate of approximately 10%, while Malawi has only 1%

• South Africa has the largest pesticide usage (26,857 tons), but the usage per unit area (2.2 kg/ha) is still lower than the global average

• Ethiopia: Herbicide import value has increased fourfold in ten years, and the application area on grain crops has doubled to over 25%

• Nigeria: Glufosinate sales increased from 100,000 liters in 2022 to 20 million liters in 2025 (a 200-fold growth), mainly due to the ban on paraquat

• Kenya: Increased from less than 2% in 2007 to approximately 10%, with a slight decline in recent years

II. Main Types and Applications of Herbicides

• Glyphosate: The most widely used (accounting for 45% of products and 34% of single-agent products), non-selective, suitable for no-till systems

• Atrazine: Used for pre-emergence treatment of grain crops such as corn and sorghum, with good control effect but high environmental risks

• Paraquat: Historically widely used, but banned in many countries (such as Nigeria), with a shift to glufosinate

• 2,4-D: Controls broadleaf weeds, widely used in rice and other crops

• Butachlor: A major herbicide in rice-growing areas, such as the Bontanga Irrigation District in northern Ghana

• Corn: The most important crop for herbicide application, especially in West and East Africa; 73% of corn-growing areas in Ghana use herbicides

• Wheat: Herbicides are used on approximately 120,000 hectares of wheat in Kenya

• Cotton: Production areas such as northern Cameroon rely on herbicides to replace traditional tillage

• Rice: Butachlor, acetochlor, etc., are used in West Africa and Madagascar

• Sugarcane: Precision spraying using drones is adopted in South Africa and other regions to improve efficiency and reduce risks

III. Application Methods and Technologies

1. Foliar Spraying: The most common (accounting for the largest market share), low-cost, using knapsack sprayers, suitable for smallholder farmers

2. Soil Treatment: Applied pre-emergence to prevent weed germination and reduce subsequent herbicide use

3. No-Till Matching: A combination of glyphosate and paraquat is used for no-till sowing, reducing erosion and increasing rainwater absorption (up to 5 times)

• 70% of farmers lack formal education, relying on dealer guidance, and only a few (less than 23%) receive extension services

• 54% of farmers randomly discard pesticide packaging, and only 1% dispose of it in accordance with environmental standards, posing pollution risks

• Countries such as Nigeria are shifting from traditional "blanket spraying" to precision spraying to reduce usage

IV. Impact on Agricultural Production

• Ethiopia: Fields using pesticides yield an additional 19-32 US dollars per mu compared to those not using pesticides

• Nigeria: Yield increases by 68-85 US dollars per mu, corn yield can be doubled, and production costs are reduced by 61%

• Tanzania: Yield increases by 40-62 US dollars per mu; Uganda: Yield increases by 38-52 US dollars per mu

• Ghana: In corn cultivation, herbicides save 60% of costs compared to manual weeding and increase yield by 30%

• Herbicide application reduces weed control labor demand by 50-90%, which is particularly significant for female farmers, alleviating heavy manual labor

• Northern Cameroon: Herbicides have expanded cotton cultivation areas, enabling production to be maintained even as family labor has decreased (due to children attending school and young people migrating for work)

V. Challenges Faced

1. Environmental Risks

• Herbicide residue pollution of water sources: The concentration of simazine in South African rivers reaches 1.82 mg/L, exceeding safety standards

• Damage to soil microbial communities, affecting nutrient cycling and leading to long-term decline in soil fertility

• Death of non-target organisms (such as bees and ladybugs), reducing biodiversity

2. Health Hazards

• Nigeria: 2,4-D residues in food crops reach 0.59 mg/kg, nearly 6 times the national standard (0.1 mg/kg)

• South Africa: Forestry workers' families are indirectly exposed through "brought-home" herbicide residues, increasing risks

• Ghana: 70% of farmers lack protective equipment, leading to high risks of direct herbicide exposure

3. Weed Resistance

• Long-term single use leads to the development of weed resistance; for example, resistance to atrazine and glyphosate has emerged in West Africa

• Insufficient resistance management measures and lack of guidance on rotation and mixing

VI. Innovation and Sustainable Development

1. Breakthroughs in Biological Herbicides

• Targets the parasitic "witchweed" (Striga), a malignant weed harmful to corn and other crops

• Principle: Fungal spores only infect Striga, not harming crops or other organisms

• Effect: Corn yield increases by 42-675% (reported by some farmers), with a cost of approximately 15.5 US dollars per mu

• Promotion: Commercially applied in Kenya, Ethiopia, and other countries, produced and distributed by local micro-enterprises

2. Policy Transformation and Regulatory Improvement

• Ban on High-Risk Products:

• Nigeria: Banned paraquat and shifted to low-toxicity glufosinate

• Togo: Fully banned the import, sale, and use of glyphosate since 2019

• Burkina Faso: Restricted highly toxic pesticides and promoted biological control

• Regulatory System Construction:

• South Africa has established a comprehensive pesticide management policy, registering and supervising over 3,000 products

• Botswana has legislated that all agricultural chemicals must be registered, with severe penalties for violations

• Regional Coordination: West African countries are striving to unify pesticide standards, but progress is slow (e.g., differing attitudes towards paraquat and atrazine)

3. Precision and Sustainable Application

• Precision Spraying Technology:

• South Africa, Kenya, and other countries promote drone spraying to improve accuracy and reduce usage by 30-50%

• Decision Support Tools (DST): In Kenyan potato cultivation, the number of spraying times has been reduced from 12 to 6, halving environmental impact while maintaining yield

• Integrated Weed Management:

• Cover crop + herbicide combination: Reduces herbicide usage by 60% and improves soil fertility

• Intercropping systems: Such as corn-cowpea intercropping, which both increases yield and suppresses weeds, reducing costs by 67%

• "Trinity" strategy of resistant varieties + biological control + chemical weeding, especially targeting malignant weeds such as Striga

VII. Future Outlook

1. Expansion of the Biological Herbicide Market: The compound annual growth rate is expected to reach 15% from 2025 to 2030, gradually replacing 10-15% of the chemical herbicide market

2. Technological Upgrading and Precision Application:

3. Mobile APP-guided spraying: Provides dosage, timing, and safety information to make up for the lack of extension services

4. Low-cost sensors: Monitor weed density to achieve "on-demand spraying" and reduce usage by 30-40%

5. Strengthened Regional Cooperation:

6. The African Union is promoting the integration of pesticide management, planning to unify registration standards by 2028

7. The Common Market for Eastern and Southern Africa (COMESA) has launched a mutual recognition mechanism for pesticide residue standards