Use of marigolds to control nematodes

I am an agribusiness adviser teaching farmers modern methods of farming, nursery and crop production. Unfortunately, in Kenya, real estate development is leaving little land under cultivation which is a challenge in crop production on top of an increase in pest and diseases infestation.  With a rise in population, there is a call to produce healthy food at a cheaper cost.

Being passionate about producing healthy food at a low cost and to ensure a zero hunger nation and eradicate poverty, I realized one of the significant challenges affecting tomatoes farmers in the greenhouse was the root knot nematode. The nematode survives by feeding directly off of the nutrients pumped through tomato roots forming the galls.

To control this nematode, I planted marigolds in companion with the tomatoes. The marigolds are also affected by the nematodes but produce a chemical Alpha-terthienyl, that acts as a nematicide to the nematodes killing them and thus reducing their population in the soil.

My finding was that the marigolds played a significant role to control the nematodes since where the marigolds ware planted in companion with the tomatoes fewer galls were found on the tomatoes roots.

On my second trial marigolds were planted as a rotation crop and played a significant role in controlling the nematodes compared to the companion planting, which is less costly compared to the chemical methods. The marigolds also helped to control pests since they were more attracted to the flower than the tomatoes.

Through this, I focused on creating awareness among farmers, youth and women on how to control the nematodes using the marigolds through an apprenticeship program that is offered in my institution.

This concept has been warmly received, and people are moving swiftly towards its implementation. The beneficiaries of this concept are mainly tomatoes farmers who visit our training center.

I am planning more education to more farmers in my locality and to extract the chemical in the marigolds and drench the soil rather than planting the marigolds.

I intend to plant more marigolds to obtain extracts from the roots. The extracts are to be derived by harvesting and simultaneously steaming the roots. After which the extract is distilled collecting the liquid and disposing of the residues. This is a cheaper method and does not require skilled labor. After the extraction, the chemical can be preserved as a bio-pesticide and used in the future. Apart from the killing the nematodes marigolds control the aphids and housefly. 

To ensure sustainability, I tend to create more awareness among people in my locality and continue planting the marigolds as a flower garden species for aesthetic value. The Tagetes minuta and Tagetes patula would be good since they produce attractive yellow/orange flowers.  In future I am looking forward to developing a gadget or small machine that can be used to extracts the chemicals from the marigold making it less difficult and less time-consuming.

Currently, our institution laboratory has simple extraction tools that we intend to use as we look forward to getting more advanced equipment.

In my daily routine as a trainer to youth in an apprenticeship program, I encourage the integration of pest and disease management especially the cultural aspects such as companion planting, maintaining the farm hygiene by disposing of all the waste appropriately since this plays a significant role in controlling pest and diseases. In addition to this, I intend to involve the students during the procedure so that they can get hands-on skills on chemical extraction.

Every week I write articles to local newspaper Seeds of Gold pullout from the Daily Nation newspaper to educate farmers on modern techniques of farming, identification of pest and diseases, using Integrated Pest and Disease Management and Integrated Soil fertility Management to ensure sustainable production of food and encourage biodiversity. I intend to take this opportunity and create more awareness about the benefits of this marigolds countrywide.

Ann Macharia, Kenya


  1. Good job continue inspiring people and educating them so that in future we will not have strikes of hunger.


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