When I recently attended the 1st International Conference on Agroecology – Transforming Agriculture & Food Systems in Africa, one of the research posters on display drew my attention. Effective microorganisms® are a commercial mix of beneficial bacteria, yeast and other living things. A team in Mozambique had found that the microorganisms not only controlled Oidium or powdery mildew, a serious fungal disease in cashew, but also managed the devastating sap-sucking bug that deforms nuts and causes their premature fall. Or at least that is what the title said.

Professor Panfilo Tabora had been working for many years with cashew. Not knowing that I was an avid fan of the weaver ant, Oecophylla, a tree-dwelling predator, Panfilo gently explained to me that the microorganisms attracted the weaver ant to the cashew trees. “The ants were a bonus,� he said with a smile. I knew that weaver ants effectively control bugs, but now I was completely intrigued: how on earth would microorganisms attract ants?

“Earlier, farmers helped the weaver ants to colonize new trees by putting ropes between trees so the ants could colonise new trees and attack bugs and other pests,� Panfilo explained me. “But when farmers started spraying fungicides the ants disappeared.�

For several years, Panfilo and his colleagues began to teach villagers to make their own liquid molasses from dried and stored cashew apples as a source of sugar, minerals and amino acids to feed and multiply the microorganisms. So the farmers made molasses to feed the effective microorganisms, which controlled the Oidium. But even when the fermented solution was ready to spray on the trees it was still sweet. “When farmers spray their trees with the solution, the sweet liquid and amino acids attracts the ants.�

Although the poster did not tell the full story, there was still truth in saying that microorganisms controlled the fungal disease and the pest, in reality it was the fermented solution that attracted the ants, which controlled the bugs. Still, even such a roundabout pest control is worth having.  

I felt reassured to know that valuable ancient technologies of biological control, such as weaver ant husbandry, have a future when combined with modern agroecological technologies that restore rather than kill ecosystems.

“And we discovered a few more unintended benefits,� Professor Panfilo continued. “By spraying the tree canopies with microorganisms, farmers are no longer exposed to pesticides and can reduce the cost of pruning.� As pesticides are expensive and harmful, farmers need to move quickly from one tree to the next to spray the outside canopy of the trees, or else they will get covered with chemicals. But as these effective microorganisms are safe for people, farmers can actually spray the under-canopies from below. The tree canopies often touch one another, which also helps the ants to move between trees. Instead of pruning every year, Prof Panfilo’s team tells farmers to just prune once every other year, or even every three years so as to have more terminals for flowering and fruiting and to let the ants move from tree to tree. All of this adds up to more yield.

At that stage, I was so impressed that I had a hard time absorbing yet another unintended benefit of this organic technology. In Mozambique, as in many other countries, farmers use the fallen cashew apples to make cashew apple juice. “By spraying cashew trees with effective microorganisms, it acts as an anti-oxidant so the juice retains its clear colour for at least 2 months,� said Panfilo.

Quite a few of the presentations at the conference had nicely illustrated the benefits of organic agriculture to people and the environment, but Prof Panfilo and his team stood out because they illustrated how the introduction of even a single, modern eco-technology can have such a wide range of benefits.

Not all microorganisms are bad, as people in the industry, schools and media often wants us to make believe. Thanks to the work of practical researchers, we learn that this healthy mix of microscopic flora can cure mildew, attract ants that kill pests, provide a safe alternative to pesticides and stop cashew fruit juice from oxidizing for months.

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