Research and Development

Nematode and Soil Fungal Biological Control Solutions The Nico Orgo Viewpoint



Nematodes are a diverse animal phylum inhabiting a very broad range of environments. They are ubiquitous in all habitats that provide available organic carbon sources. They are the planet’s most abundant metazoa. They range in reproductive potential from explosive opportunists to conservative survivalists. Because they are transparent, their diagnostic internal features can be seen without dissection. They can, therefore, be identified without biochemical procedures. They also contribute to a variety of functions within the soil system. As in agricultural systems, nematodes can enhance nutrient mineralization and act as biological control agents. They vary in sensitivity to pollutants and environmental disturbance.

Nematode infestations belong to the major stresses, affecting crop production worldwide. “The estimated annual yield losses go up to 12 percent due to plant parasitic nematodes in the world’s major crops,” points out Kartik Laijawala director of Nico Orgo Company. He added, “In India alone, recent estimates show, nematodes are responsible for both quantitative and qualitative yield losses amounting to about $300 million per year. Damages are especially big on crops like banana, sweet potato and sugar beet.”

Nematodes leave the plant of resistance and synthetic nematicides indiscriminately destroy beneficial soil fauna. Common fungal diseases in soils also cause big damages. “Fusarium, Pythium and Rhizoctonia pose the greatest risk to healthy roots and soils and, if not treated, it can even cause complete failure in affected plants. Just like nematodes, they exist out of sight, in the root zone and so many farmers lack the necessary awareness to combat them” said Laijawala.

Chemical solutions exist but many are now unviable in terms of what they do to the environment and human health. Methyl bromide and carbofuran are all recognised toxic chemicals and banned in several parts of the world. Laijawala states, “Proper solutions have been found with organic pest control, botanical and biological alternatives. The solutions need to be studied and barriers to entry must be eased for quicker uptake.” He describes three useful bio-control agents:

• Paecilomyces Lilacinus: A beneficial fungus which controls several species of nematodes;

• Trichoderma Viride: A beneficial fungus antagonistic to fungal pathogens such as fusarium, pythium, and rhizoctonia;

• Pseudomonas Fluorescens: A microbial agent which protects roots against both fungi and nematodes.

Paecilomyces Lilacinus is a parasitic fungus that attracts the sedentary stages of nematodes. It colonises nematode egg masses, severely affecting nematode populations. It destroys up to 90 percent of eggs and 75-80 percent of egg masses.

Trichoderma Viride is one of the strongest soil-borne fungal species, it is antagonistic to several economically-important pathogens such as rhizoctonia and fusarium. Additionally, it acts as a bio fertiliser due to its ability to solubilise phosphates in the soil and quickly decompose organic matter. Mode of action of trichoderma viride has the ability to colonise the surface of the seed and kill the pathogens present on its surface. However, it can protect the plant through its life cycle through mycoparasitism and antibiosis.

Pseudomonas fluorescens is the ‘superman’ of the bacterial world! It acts as a nematicide, fungicide and can also aid in growth promotion. It is non-specific in its ability to protect plants and, once established, it works against several different pathogens while inducing systemic resistance in the host plant. It produces secondary metabolites which play an important role in plant disease suppression. Pseudomonas fluorescens aggressively colonises the roots of the crop and suppresses disease by inhibiting phytopathogens in the soil or on the roots by competition.

According to Laijawala, there are several advantages of using these three biological agents, the first being ‘eco friendly’: zero residual toxicity and total degradability. They are non toxic to humans, animals, plants and predators of insects. These two biological agents can be used at all stages of crops. They promote plant growth and do not lead to development of resistance in plant pathogens. Some of them, such as Trichoderma Viride, have also an effect to help nutrient uptake. Formulated as ‘living’ products, these biological agents need some precautions; they must be applied during evening hours (cooler temperature), and if conditions are dry, the field should be irrigated before application. Chemical fertilisers and insecticides should not be sprayed 5-7 days before or after, for best results. Also, these biological products need to be stored in a cool place away from direct light and heat. Since these products work primarily in the soil, they are considered effective on most crops, ranging from fruits and vegetables, to plantation and ornamentals. They can also be used for landscapes, forestry, turf management and home gardening, which means, a wide range of possibilities in the future.

Author

Kartik Laijawala is a Partner with Nico Orgo Manure.