Biological control of plant diseases using Trichoderma SP

Bendangsenla and Susanta Banik
Department of Plant Pathology, School of Agricultural Sciences, Medziphema Campus, Nagaland University

A large amount of crop loss occurs each year during both pre and post-harvest stages due to pathogen infestation that involves a wide variety of pathogens ranging from viroids and viruses to prokaryotic bacteria, eukaryotic fungi, oomycetes, and nematodes. These plant pathogens are highly persistent in their attack and induce direct and indirect losses to the tune of 40 billion dollars worldwide.

Given the paramount importance of the methods for controlling plant pathogens and diseases caused by them to improve productivity not only in terms of food but also for other materials obtained from plants like fibre, timber, oils, medicines, etc.

 and to meet the food demands of the exponentially growing world population, food production needs to increase by 70% by the year 2050 to address the internationally growing food security concerns. It is high time when we need to shift to sustainable methods of agriculture so as to reduce biodiversity loss and greenhouse gas emissions that are currently placed at 60% and 25%, respectively. At present, most of the methods employed for plantprotection from pathogens primarily involve the use of antibiotics and chemicals. Even though these shotgun methods deliver immediate protection, they ultimately lead to resistance and bioaccumulation of harmful chemicals in the crop systems. It is these drawbacks that emphasize the importance of sustainable and environment-friendly crop management practices to control diseases.Such practices help to improve the quality and quantity of agricultural produce that also includes organic crops.Overall, due to the growing concerns of environmental pollution and ecological toxicity resulting from the indiscriminate use of chemical formulations, there is an immediate need to base modern plant protection strategies on natural resources.

Biological control of plant diseases can be broadly defined as the use of one organism to influence the activities of a plant pathogen. Biocontrol organisms can be fungi, bacteria, or nematodes. Biocontrol organisms work by competing with the pathogen for space and nutrients, by parasitism or predation, by inducing the plant’s natural defense system, and/or by the production of antimicrobial substances (antibiotics like streptomycin). Often several mechanisms function together to make an organism effective.These products are living organisms or dried spore preparations and must be handled differently than conventional fungicides. They are sensitive to temperature extremes and must be applied immediately after mixing with water. They may also require special attention to pH, exposure to chlorine or UV light, and their shelf life may be limited.

Biological control is dependent on numerous agonistic and antagonistic interconnections between plants and microbes living in the rhizosphere and phyllosphere and their application to minimize disease and subdue pests. Organisms from the rhizosphere can be harnessed from the surrounding environment (the black box approach) or can be introduced into the field from external sources (the silver bullet approach). It is beneficial to apply a consortium of microbes with collaborative properties rather than relying on a single organism since microbial consortia make up a stable rhizosphere that offers more effective control against pathogens. Apart from microbial applications, the utilization of other plant products like extracts, biofertilizers, and biopesticides, natural enemies of pests and pathogens, and gene products also aid in carrying out biological control.

Trichoderma, a biological fungus widely used for plant pest control, mainly exists in the soil, air, plant surface, and other ecological environments and can effectively control a variety of plant diseases. Trichoderma is mainly used to control soil-borne diseases in various plants and some leaf and spike diseases. Trichoderma can prevent disease, promote plant growth, improve nutrient utilization efficiency, enhance plant resistance, and repair agrochemical pollution. There are more than 370 Trichoderma sp. including T. harzianum, T. viride, T. asperellum, T. hamatum, T. atroviride, T. koningii, T. longibrachiatum and T. aureoviride. Many studies have shown that most Trichoderma sp. can produce bioactive substances and have antagonistic effects on plant-pathogenic fungi and plant-pathogenic nematodes. These bioactive substances, including secondary metabolites and cell wall-degrading enzymes, can effectively improve crop resistance, reduce plant diseases, and promote plant growth.

Application of Trichoderma sp. in biological control of plant fungal diseases
Trichoderma is a biocontrol fungus widely distributed worldwide. Trichoderma has a huge application value and potential in the field of biological control of plant diseases.Research on the use of Trichoderma to control plant diseases has been reported worldwide. T. viride and T. harzianum have different degrees of inhibitory effects on 29 species of plant pathogenic fungi belonging to 18 genera, including Botrytis, Fusarium and Rhizoctonia. Trichoderma has control effects on a variety of plant pathogenic fungi, such as Rhizoctonia solani, Pythium ultimum, Fusarium oxysporum, Sclerotinia sclerotiorum, Botrytis cinerea, Pseudocercospora sp. and Colletotrichum sp.Trichoderma has been widely used for the biological control of cotton verticillium wilt, crop graymold, tomato graymold, melon wilt, potato dry rot, tobacco root rot, and other plant diseases. T. harzianum has a good control effect on pepper and potato Phytophthora blight. It can inhibit the growth of Phytophthora blight in soil, reduce the number of pathogenic fungi, and effectively reduce the rate of dead seedlings and disease index of plants.

With the increasingly mature biological control technology, the types of commercial preparations for Trichoderma sp. are also becoming diverse. There are four main categories: (1) Wettable powders, which are made by mixing conidia powder, powdery carriers, and humectant. (2) Granules are made by mixing and stirring conidia and carrier. (3) A mixture consisting of spore powder and chemical fungicides mixed in proportion on a suitable carrier. (4) Suspenso-emulsion is prepared by suspending conidia in a lotion composed of vegetable oil, mineral oil, emulsifier, etc. In the current market for Trichoderma biological agents, T. harzianum is the largest, followed by T. viride and T. koningii. The most widely Trichodermasp products are formulated in a wet table powder or granules. Ninety percent of various Trichoderma strains are applied to crops, with the aim to control plant diseases due to antagonistic characteristic expressed by them against phytopathogen. The impact of their usage as a biocontrol agent (BCA) on the field is evaluated on the input cost and in relation to crop productivity. As a result, it was found that the input cost and crop productivity application of BCA are economical and low cost compared to synthetic inputs
Therefore, using Trichoderma to prevent and control plant diseases can not only inhibit the growth of pathogenic fungi, which is conducive to plant growth but can also reduce the use of chemical pesticides, which is conducive to protecting the ecological environment.

Some examples of plant pathogens and their biocontrol strategies using Trichoderma sp. are listed below:

Sl. No.

Name of the disease

Crop

Causal agent

Biocontrol strain

1.

Root rot disease

Soybean

 

Corn

 

Pepper plants

Brinjal

Pythium arrhenomanesf.sp.adzuki

Fusarium oxysporumf.sp.adzuki

Rhizoctonia solani

Macrophominaphaseolina

Trichodermaviride

T. viride

 

T. asperellum

T.harzianum

2.

Damping off

Pepper, cucumber, cotton, sugar beet

Phytophthora capsici, Pythiumsp. and Rhizoctonia solani

T.harzianum

3.

Wilt

Tomato, melon

Fusariumoxysporumf.sp. lycopersici(FOL), F. oxysporum

T.asperellum,T. harzianum

4.

Fruit rot

Chilli, tomato

Alternariatenuis, Rhizoctoniasolani

T. harzianum

T. viride

5.

Head blight

Wheat and other small grain cereals

Fusariumgraminearum, Fusariumculmorum

T. gamsii

6.

Sheath blight of rice

Rice

Rhizoctoniasolani

T.harzianum

7.

Blossom blight

Alfalfa

Sclerotinia sclerotiorum

T. atroviride

8.

Collar rot

Tomato

Sclerotiumrolfsii

T. harzianum

References
https://ag.umass.edu/vegetable/fact-sheets/biological-control-of-plant-diseases#:~:text=Biocontrol%20organisms%20work%20by%20competing,to%20make%20an%20organism%20effective.
Pandit, MA., Kumar, J., Gulati, S., Bhandari, N., Mehta, P., Katyal, R., Rawat, CD., Mishra, V., Kaur, J. 2022. Major Biological Control Strategies for Plant Pathogens. Pathogens. 11: 273. https:// doi.org/10.3390/pathogens11020273.
Yao, X., Guo, H., Zhang, K., Zhao, M., Ruan, J and Chen, J. 2023.Trichoderma and its role in biological control of plant fungal and nematode disease. Frontiers in Microbiology. 14:1160551. doi: 10.3389/fmicb.2023.1160551.
Zin, N A and Badaluddin, N A. 2020.Biological functions of Trichoderma spp. for agriculture applications. Annals of Agricultural Sciences.65: 168–178.



Support The Morung Express.
Your Contributions Matter
Click Here