Kenya: Biological solutions meet peri-urban horticulture

Biological control involves the management of plant pests and diseases using other organisms. The concept relies on an active human management role to achieve this and is an important component of integrated pest management (IPM) programs.
 

There are three basic strategies for biological pest control. The first, which is referred to as classical, is where a natural enemy of a pest is introduced into the environment to achieve area-wide control. Inductive control on the other hand is when a large population of natural enemies is administered for quick pest control in a specific crop. Finally, inoculative is when measures are taken to maintain natural enemies through regular re-establishment.
 

Peri-urban horticulture, which can be described as the growing of crops around major commercial settlements, is an increasing trend in Kenya. Farmers are able to easily access the market because of the high population concentration of city dwellers, such as is the case with Nairobi and its environs. This typically involves intensive growing of crops on small farms and often entails the use of greenhouses or small tunnels. Crop protection activities are an important part of the production process.

 

In view of the proximity to the market, peri-urban growers need to be aware and concerned about food safety, particularly with regards to chemical pesticide residue levels in their produce. This subject is often discussed when addressing export produce destined for markets such as Europe but is seldom addressed when it comes to food for local consumption.
 

Koppert has for the last twelve years offered inductive biological solutions for Kenyan flower growers. This has enabled them to successfully manage major pests in a sustainable manner by reducing dependence of chemical pesticides. The same concept and tools, if adopted in peri-urban horticulture, could enable farmers to deliver safe food to the market. This is where biological solutions meet peri-urban horticulture.
 

In 2017, Koppert piloted the use of biological control in a couple of locations around Nairobi. This included Marp Farm in Kamulu -Machakos County, and Grace Rock Farm in Rironi - Kiambu County. The crops grown by the said farmers were tomato and capsicum (sweet pepper) respectively. The program entailed the use of biological solutions such as the predatory bug Macrolophus pygmaeus (tradename “Mirical”) to manage whitefly and Tuta absoluta (tomato leaf miner) in tomato. For the capsicum crop, the predatory mite Amblyseius swirskii (tradename Swirski-Mite) was used to manage thrips and whitefly in the crop. This was done alongside other useful tools such as pheromone traps (Pherodis-Tuta and Tutasan water traps) and sticky traps (Rollertrap and Horiver). In order to manage soil-borne pathogens, the beneficial fungus Trichoderma harzianum (Trianum) was used. In the tomato crop, the botanical fungicide NoPath was used to manage diseases such as Early Blight (Alternaria solani) and Late Blight (Phythophthora infestans). The NatuGro system was further used to enhance the soil environment, resulting in a stronger, healthier and more resilient crop.
 

Overall the program was a big success with the farmers recording a clean healthy crop in the greenhouse tunnels under the Koppert IPM program compared with the tunnels managed under the standard practice. They also recorded much higher yields of residue-free produce that fetched them premium prices in the market. “I harvested 6 tonnes of tomato from the IPM tunnel” says Mrs. Mary Nyaga of Marp Farm. “I only made 2 sprays of insecticide over the entire 9 months period of the crop”, she says proudly. “I continued harvesting the crop for an extra 4 weeks after the regular tunnel had already been pulled out”, she added.
 

Mrs.Njeru Mwihaki of Grace Rock Farms had only good things to report about the IPM program in her capsicum crop. “I have used Trianum in my commercial propagation project over the last 2 years. This not only helps me manage soil-borne pathogens in the seedlings but also ensure that the seedlings I sell to my clients are healthy and strong”, she adds.