Key Sector: Herbicide & Pesticide

Each month, the World Food Bank features an in-depth look at the importance of each of the 12 key agricultural sectors in which we work. This month, we are looking at the sectors of both herbicide and pesticide.

Herbicides

Much of farming is about timing—when to plant, when to irrigate, and when to harvest are essential to the farming cycle. However, herbicide management is equally important for more significant yields and should be implemented at the most appropriate times during that complex cycle. An Outlooks on Pest Management article explains that in sub-Saharan Africa, crop yields are lower than global averages, and specifically, “smallholder maize yields are typically 1–2 tons per hectare compared to 8 tons per hectare achieved on regional research plots” where researchers weed and fertilize at optimal times and in optimal amounts. Additionally, “keeping the crop free of weeds for the first third of [the crop’s] life cycle” aids in more abundant results.

When compared to European and North American farmland, sub-Saharan Africa’s tropical regions produce more weeds, making weed management and the use of herbicides significantly more important to successful farming. Gianessi and Williams argue that weeds are the main constraint on agricultural production. When not managed, weeds compete for water, nutrients, and space, minimizing the potential of crop development and yield. The methods in which farmers might reduce or eliminate weeds varies. Hand weeding, though not always implemented in a timely fashion, is used more widely among sub-Saharan smallholder farmers and is predominantly performed by women and children. Women contribute to more than 90% of hand weeding for smallholder farming, but herbicide use is becoming more widespread among larger farms.

In the same way that hand weeding can improve crop yields, if implemented effectively, herbicides require timely application in order to gain productive results. Herbicides can be applied directly to the soil before planting to eliminate weeds before they germinate, ultimately reducing the labor needed for hand weeding as crops develop. Despite the use of herbicides across estate farms, Outlooks suggests that herbicide use in Uganda was only at 0.1% of acres treated for weeds on farmland in 2011. While researchers suggest that herbicides are more effective and reduce the cost of labor, herbicides are generally not implemented in farming practices because of lack of information and technology to do so. Gianessi and Williams explain that “the greatest obstacle between herbicide technology and African farmers is lack of awareness and training,” which includes where to purchase chemical products. Overall, weed control allows for stronger responses to fertilizers and more abundant yields.

Pesticides

While weeds are harmful to African farmlands, insects generally attack crops more violently. The Conversation suggests that “insect pests cause almost half of the crop losses in Africa,” and that the use of pesticides should be combined with other methods to reduce harvest loss. Additionally, pesticide use is increasing across the continent because they are effective, reducing the presence of pests and increasing overall yields.

The major problem with pesticide use is its effect on the environment and its danger to those who use them. Unregulated pesticides circulate because they are inexpensive, but pests become resistant to them and farmers are unable to use them safely because they lack clear instruction or direction at all. To reduce danger, some research centers are suggesting the use of IPM or Integrated Pest Management. This method “focuses on long-term prevention of pests” through “a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties.” Once this method is in place, the use of pesticides only enters after monitoring the need for a target organism.

While pesticides can be used sparingly and carefully to eliminate insects, overuse can cause harm. Crop rotation, natural enemies, and changes in irrigation practices can all be used in coordination with chemical control of pests to reduce the amounts of chemicals applied. Also, much like herbicides, pesticide use lacks training resources among farmers, increasing the improper and dangerous use of them. Rahman and Chima note that in Tanzania, “only 21% of [farmers using pesticides] used the correct dose.” So it is critical that when applying these chemically-based approaches to both weeds and insects, thorough instruction should precede for effective and safe use.