20 Apr The many benefits of healthy vegetable seedling systems
Danny Coyne, Laura Cortada, and Joseph Kisitu
Everywhere across the globe, children are always encouraged to eat their vegetables for a healthy diet, as fresh vegetables play an important role in nutrition. In sub-Saharan Africa (SSA), peri-urban vegetable farming can be quite lucrative. Surging rural-urban migration is resulting in rapid urbanization, requiring ever greater supplies of fresh food, especially nutritious but perishable vegetables. Vegetables, such as capsicum pepper and tomatoes, are particularly affected by pests and diseases. Their production, therefore, tends to attract more pesticide use than most other crops in the region. Given the often poor awareness of farmers regarding pesticide use and safety, we need to ask ourselves how healthy the vegetables we get in the market are.
The answer can be alarming, with weekly pesticide sprays repeatedly administered by farmers who have little understanding of what, why, or how they need to apply such toxic chemicals. (Fig. 1). Vegetable growers intensively and continuously cultivate small land areas (often <0.2 ha), which magnifies pest and disease problems, a major cause of crop loss and poor productivity. Applying synthetic pesticides is a common coping strategy, threatening the health of farmers, consumers, and the environment. Local regulatory frameworks for pesticide use are often difficult to enforce, allowing the entry and use of hazardous pesticides, including those that are banned elsewhere.
Over the past 5-6 years, together with our various partners, we have led activities in East Africa towards reducing pest and disease incidence and consequently reliance on pesticides on pepper and tomatoes. The platform for this has been the introduction and demonstration of healthy seedlings. In addition, good agronomic practices (GAPs) have been promoted, varieties assessed for disease resistance, biological control agents (BCA) evaluated, and farmers’ awareness of the correct use of pesticides improved. Healthy seedlings formed the basis of this work, with the hypothesis that healthy seedlings would be less prone to infection. Underscoring this theory was that reducing nematode infection in particular would render seedlings better able to cope with the pest and disease onslaught experienced by vegetable farmers. Nematodes, especially root-knot nematodes (Meloidogyne spp.), plague vegetable production but they are unseen and often overlooked, affecting the roots (Fig. 2). Early infection with root-knot nematodes (RKNs) can significantly impair growth and health of plants. We compared healthy seedlings prepared in the screenhouse with farmer seedlings, and then further compared resistant varieties, better practices, including appropriate but expensive pesticides and microbial biological control products from our partner RealIPM. This work was conducted in Ethiopia, Kenya, Madagascar, Tanzania, and Uganda under a number of donor-funded projects.
What we found was eye-opening! By simply introducing the use of healthy seedlings, we could effectively double farmers’ yields of tomato and pepper. Healthy seedlings germinated better, survived better, grew into stronger, more resilient, bigger plants that gave much higher yields of fruits. For example, germination was on average 40-50% better in healthy conditions in seedling trays than for traditional farmers’ practice using the same source of seeds. This immediately provides 40-50% more plants for farmers. Healthy seedlings consistently led to higher yields of about 50%, but the value of using healthy seedlings was highlighted when combined with GAPs, which in general doubled yields.
The farmers were happy with the results (Fig. 3). Farmers reported that tomatoes and peppers from healthy seedlings were generally larger, looked better, and consequently were more appealing and preferred by traders and markets. Furthermore, a key factor for farmers was that their tomatoes and peppers could be harvested earlier than those from farmers’ practice, entering the market sooner and commanding higher prices at times; harvests were better synchronized as well, reducing the financial and labor burden of transporting to local markets. A particularly outstanding finding, however, related to the use of pesticides. When using healthy seedlings and implementing GAPs, together with sound advice, pesticide applications were reduced by 75%– i.e., four times lower than conventional farmers’ practice (3.5 L/ha compared with 15.5 L/ha).
In general, prior to the project training, farmers had a limited understanding of pesticide use in terms of which were most suitable, which should be used for which diseases/pests and in their ability to correctly identify causal agents of disease and pest symptoms. We found that most farmers gained much of their information on pesticide products from the shop/storekeeper, who were not particularly expert in relating disease and pest symptoms to a product. The production of a pictorial pest and disease guide as part of the training was very well received by farmers and agricultural staff (Fig. 4). A defining factor for selection of pesticide products tended to relate to cost, and the cheapest at that.
Prior to using healthy seedlings and receiving training farmers were spraying pesticides indiscriminately on a calendar basis (usually every week) that constituted misuse and overuse of pesticides. By using healthy seedlings and implementing GAPs, the pest and disease incidence and damage were generally reduced. This was particularly notable for RKN infection, which, in turn helped to reduce additional disease infections. Although farmers were applying four times more pesticides than in the improved practice plots, pest and disease levels and damage were still higher for farmers’ practice. Cheap pesticides do not necessarily lead to savings and can turn out to be expensive when they do not work. In 2018, three BCAs to manage soil-borne pests/diseases researched in this project passed the registration process by the Ministry of Agriculture in Uganda (MAAIF) for commercialization.
This work has led to improving the safety and health of vegetable farming practices in the intensive peri-urban production systems in East Africa. Increasing yields, reducing reliance on chemical pesticides, and introducing safer alternatives benefit farmers, consumers, the public, and the environment. We now need to extend the knowledge of using healthy seedlings and other improved practices to improve vegetable farming at scale and ensure that we all eat healthy vegetables.
Projects and Donors
Federal Ministry for Economic Cooperation and Development (BMZ); Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH. Local Focus: safe and effective pest and crop management strategies to strengthen the vegetable value chain in the humid tropics. 2013-2015
Federal Ministry of Finance (MoF) of the Republic of Austria; Austrian Development Agency (ADA): Healthy seedling systems for safer, more productive vegetables in East Africa. 2015-2018
U.S. Agency for International Development (USAID): Feed the Future. Integrating vegetables into maize-based systems for enhanced nutrition and income generation. 2013-2015