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39 species of oyster mushrooms have been discovered in Colombia.

These fungi could be effective nematicides in banana and tomato crops.

The biological control research project was carried out in the Province of Caldas given the high production of banana and tomato crops.

This fungus is much appreciated by national and international cuisine.

This fungus based biological nematicide would also be effective in coffee crops.

One of these fungi is known as Pleurotus or oyster mushrooms. In Colombia there are 39 species of oyster mushrooms. 

This fungus is much appreciated by national and international cuisine due to its nutritional quality and its medicinal properties including being anticarcinogenic, cholesterol and hypertension reducing, antithrombotic, and anti-diabetic. Furthermore it is considered a dietary supplement with enzymes and metabolic products with great industry potential. 

Universidad Nacional de Colombia (UNal) in Palmira Agrarian Sciences master’s candidate Janeth Alexandra Sierra Monroy assessed the in vitro and in vivo nematicide action of three species of Pleurotus fungi (P. ostreatus, P. sajor-caju and P. pulmonarius) on Radopholus sp. and Meloidogyne spp. nematodes. 

“The fungi mycelium produces toxins which attack nematodes and paralyze them and then colonize and digest them completely, ultimately using their mass as nitrogen source,” said Sierra. 

Paralyzing and devouring 

The biological control research project was carried out in the Province of Caldas given the high production of banana and tomato crops, which is 20,510 hectares (ha) of banana and 1,052 ha of tomato which are highly susceptible to nematode attacks. 

In the laboratory stage tests she used a mixture of fungi in concentrations of 20, 50 and 75 grams (g) in 200 milliliters (ml) of sterile distilled water (SDW) on 25 nematodes, including a chemical treatment of 330 parts per million (ppm) and a commercial biological fungus at a rate of 2 g/L, during 24, 48 and 72 hours of exposure. 

She recorded the amount of moving nematodes; immobile nematodes were softly touched with a needle and some reacted and were recorded as active. However, the organisms which did not display mobility were extracted from the analyzed mixture and placed in petri dishes with sterile distilled water for 24 hours in total darkness.

“Once the time had passed they carried out the mobility assessment and the nematodes which finally did not show activity were recorded as dead individuals,” she said.

Treatment of P. ostreatus on the control Meloidogyne spp. such as P. sajor-caju on Radopholus showed to be efficient at 72 hours with an application of 75 g. 

For the field test stage, they used P. ostreatus on Meloidogyne nematodes in tomato seedlings and P. sajor-caju on Radopholus nematodes on bananas in concentrations of 75 g and 150 g in 200 ml. 

The fungi tested on plant seedlings were effective for the control of Meloidogyne spp. and Radopholus sp. nematodes as it reduced its presence between 64% and 53% respectively, in face of concentrations of 150 g compared to control crops. 

This research project is part of a macro project entitled, “Development of microbial innocula with nematicide, bactericide and breaking down action in situ coffee, and banana crops” carried out at the Laboratory of Microbiology of the Natural Resources and Preservation Management Department of the Nacional Coffee Research Center (Cenicafé, for its Spanish acronym), and the firm Soluciones Microbianas del Trópico Ltda. 

The results offer scientific support to companies and organizations devoted to providing alternatives to sanitary issues to the agricultural and livestock issues of the country. 

Although application of chemical products is one of the management measures to control these larvae, it effectiveness is not very successful as it only temporarily reduces populations, therefore farmers need to carry out constant applications, producing high toxicity levels for the environment and human health.