Rhizoctonia solani in Potato Crops.
Part II
Control Strategies.
Product selected for the Inovation Tour at Interpom 2024, Belgium.
1. Introduction
This Blog presents the new solution developed and registered by Biocontrol Technologies; Rootdei® Biocontrol Biofungicide, as an effective solution for the control of Rhizoctonia solani.
R. solani is the main soilborne fungal pathogen affecting potato crops, causing the symptoms known as Black Scurf and Stem and Stolons Canker*. Certain agricultural practices and plant protection products used synergistically can reduce the severity of the disease. In the context of climate emergency and the European Green Deal 2030, biopesticides such as RootDei Biocontrol are increasingly needed for sustainable crop disease control.
2. Rootdei Biocontrol® for the Control of Rhizoctonia solani.
Within the control strategies for the pathogen R. solani, the biofungicide RootDei Biocontrol® stands out as a highly effective biological solution. Formulated with Trichoderma asperellum strain T34, a highly active beneficial fungus with great disease control potential, RootDei® Biocontrol also offers an increase in the quality and number of harvested potatoes. The high concentration of its formulation and its biological activity allows working with low doses (250g/ha) and with a single application at the beginning of the crop.
RootDei® Biocontrol is a product registered in Europe, Regulation (EC) 1107/2009 for use as a biological crop protection product for the control of Rhizoctonia solani. This means that it has demonstrated its efficacy and safety (toxicological and ecotoxicological studies) in addition to being a residue-free product. Its authorization against this pathogen is based on official trials conducted under Good Experimental Practices (GEP), studies executed by authorized companies with a set of guidelines and standards that guarantee that they are carried out in a rigorous and reproducible manner, complying with high quality and reliability criteria.
In addition, RootDei Biocontrol® has been selected as an innovative product at the Interpom 2024 fair dedicated to the potato production sector held in Belgium during the month of November, being selected as part of the Innovation Tour* that will take place.
Mechanisms of Action of RootDei Biocontrol® in the control of Rhizoctonia solani.
One of the strengths of RootDei Biocontrol® is its multiple mechanisms of action to control the disease, which allow an effective control of Rhizoctonia solani and a reduction of its sclerotia (forms of persistence in the soil).
In addition, the fact of having multiple mechanisms of action means that it is very unlikely for the pathogen to develop genetic resistance to the active ingredient of RootDei Biocontrol®, the fungus Trichoderma asperellum strain T34, which has been considered by the FRAC (Fungicide Resistance Action Committee) as a fungicide with multiple modes of action that does not generate resistance (category BM02 of the FRAC Code List).
The different mechanisms of action are differentiated between direct mechanisms on the pathogen and beneficial effects on the plant.
A. Effects on the pathogen
Direct Mycoparasitism
RootDei Biocontrol® directly depredates phytopathogenic fungi such as Rhizoctonia solani by feeding on them through enzymatic degradation, thanks to its digestive enzymes.
Sclerotia Parasitism
RootDei Biocontrol® is also able to colonize and degrade R. solani sclerotia, inactivating their ability to germinate. This helps to reduce inoculum in the soil (lower disease pressure the following year) and in the tubers, which increases the quality of the harvested product.
Competition for space and nutrients
RootDei Biocontrol® competes with R. solani for space and nutrients, making root colonization by the pathogen significantly more difficult.
Production of Biostatic Metabolites
RootDei Biocontrol® produces metabolites that slow down the biological development of the pathogenic fungus, limiting its ability to spread.
B. Effects on the PLANT
Immune System Activation
Several scientific studies demonstrate the ability of the Trichoderma asperellum T34 strain of RootDei Biocontrol® to activate the immune system of the plant through the ISR (Induced Systemic Resistance) pathway, stimulating the expression of genes related to the immune system, which allows the plant to recognize the pathogen very quickly and to respond very actively to possible infections.
Growth Promotion
RootDei Biocontrol® has been scientifically proven to promote root growth by improving root architecture and stimulating the development of absorbent hairs. This facilitates a greater absorption of mineral elements from the soil which, together with the reduction of biotic pressure caused by pathogens, contributes to an increase in crop yield (see crop increase section).
4. Dosage and Mode of Application in the potato crop.
With a single application of 250 g/ha at the time of planting, directly in the furrow on the tubers, RootDei® Biocontrol colonizes from the beginning, protecting the tuber before the development of stems, stolons and roots, extending this protection throughout the crop cycle.
5. Disease Reduction with RootDei Biocontrol®.
As mentioned above, RootDei Biocontrol® has demonstrated its effectiveness for the control of R. solani in potato in official GEP trials. These trials have allowed the registration of RootDei Biocontrol® as a potato crop protection product in Central Europe.
The product is currently registered in Germany, and is in the process of mutual recognition in other important potato-growing countries, such as Belgium, the Netherlands and Poland.
Below are some of the results of the efficacy trials, which demonstrate a statistically significant reduction in disease, very close to the efficacy of the reference chemicals with which it has been compared.
6. Crop Increase with RootDei Biocontrol®.
Official registration trials have also shown that RootDei® Biocontrol is able to increase potato crop yields.
6. Other pathogens controlled by RootDei Biocontrol®.
In addition to R. solani, the pathogen of concern in this blog entry, RootDei has been found to be effective in controlling soil nematodes ( Globodera y Meloidogynecyst-forming or gill-forming, respectively, GEP studies in progress), also against Athelia rolfsii rot , and bacterial pathogens such as potato scab caused by Streptomyces scabies, or rots caused by other bacteria such as Pectobacterium carotovorum or Dickeya dianthicola, which adds additional value to its use in this crop.
5. Other strategies for the control of R. solani in potatoes
You can optmize the use of RootDei Biocontrol® by applying other complementary strategies that are highly recommended for the farmer as they help to prevent the disease caused by R. solani in potato.
Performing these practices in conjunction with the use of biological pesticides such as RootDei Biocontrol® is an ideal Integrated Pest and Disease Management strategy, leaving the use of chemical pesticides as the last control option.
Disease Free Certified Seed
Use of Certified Disease Free Seed:
Crop Rotation
Crop Rotation
Planting at the Right Time
Planting at the Right Time
Harvesting at the Right Time
Planting at the Right Time
Organic Matter Contribution
Organic Matter Contribution
6. Conclusions
RootDei Biocontrol® is an effective and sustainable solution for the control of Rhizoctonia solani in potato crops, standing out for its biological action and its ability to reduce the disease, as well as to increase crop yield. Formulated with Trichoderma asperellum strain T34, the biofungicide acts through multiple mechanisms, such as mycoparasitism, competition for nutrients and activation of the plant’s immune system. Its single application at crop initiation simplifies management and reduces the need for repeated applications.
In addition, complementary strategies such as the use of certified disease-free seed, crop rotation, planting under appropriate conditions and incorporation of organic matter into the soil can enhance R. solani control.
Together, these practices promote integrated disease management, aligning with the principles of the European Green Deal and favoring a more sustainable and healthy approach to potato production.
7. Sources
- Root rot, Rhizoctonia solani, Servicio Nacional de Sanidad, Inocuidad y Calidad Agroalimentaria, México: https://www.gob.mx/cms/uploads/attachment/file/600968/Pudrici_n_de_la_ra_z.pdf
- Rhizoctonia solani in potatoes and its control, University of Waeningen: https://edepot.wur.nl/305202
- Rhizoctonia Canker and Black Scurf of Potato, Cornell University: https://www.vegetables.cornell.edu/pest-management/disease-factsheets/rhizoctonia-canker-and-black-scurf-of-potato/
- Rhizoctonia stem canker and black scurf of potato, University of Idaho: https://objects.lib.uidaho.edu/uiext/uiext32100.pdf
- Bulletin #2273, Potato Facts: Rhizoctonia Diseases on Potatoes, University of maine: https://extension.umaine.edu/publications/2273e/
- Ajayi-Oyetunde, O. O., & Bradley, C. A. (2018). Rhizoctonia solani: taxonomy, population biology and management of rhizoctonia seedling disease of soybean.Plant pathology, 67(1), 3-17.
- Chaudhary, S., Lal, M., Sagar, S., Sharma, S., & Kumar, M. (2024). Black scurf of potato: Insights into biology, diagnosis, detection, host-pathogen interaction, and management strategies. Tropical Plant Pathology, 49(2), 169-192.
