Introducción

La pudrición roja del tallo, causada por Colletotrichum falcatum Went (estado conidial) [=Glomerella tucumanensis (Spegazzini) Von Arx and E. Müller] es una enfermedad ampliamente distribuida donde se cultiva de caña de azúcar (Sacharum spp.) en los trópicos (11. Olahan GS, Fatoba PO, Balogun OS. Incidence of smut and red rot diseases of sugarcane in southern part of niger state, north central Nigeria. Science World Journal. 2021; 15(2): 73-75. ISSN: 1597-6343. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.scienceworldjournal.org/article/view/20545/13637 ). En Cuba se encuentra dentro de las enfermedades detectadas desde 1915, con una amplia dispersión en las plantaciones cañeras de las empresas azucareras (22. Chinea A, Zayas E, Bruner S. Inventario de enfermedades de la caña de azúcar en Cuba: tercera etapa. Revista Cuba & Caña. 2019;22(3):8-14. ISSN: 1028-6527. Available from: https://scholar.google.com/scholar?hl=es&as_sdt=0%2C5&q=Inventario+de+enfermedades+de+la+ca%C3%B1a+de+az%C3%BAcar+en+Cuba%3A+tercera+etapa&btnG= ,33. Mayorga SA, Centeno SP, Toapanta OG, Haro YE. Efecto de Colletotrichum falcatum en los parámetros productivos de caña de azúcar, revisión integral y estrategias de manejo. Polo del Conocimiento. 2025; 10(7): 280-301. Available from: https://doi.org/10.23857/pc.v10i7.9889.).

La enfermedad ocasiona severos daños a las plantas de caña de azúcar (44. Kurian JA, Jehani M, Mohamed JM, Vaja S. Assessment and management of diverse isolates of Colletotrichum falcatum associated with red rot disease in sugarcane. International Journal of Research in Agronomy. 2024; 7(7): 417-425. Available from: https://doi.org/10.33545/2618060X.2024.v7.i7e.1062.,55. Ann J, Syafawati J, Mohd SRA, Edwina J, Ali H, Shah MR. Mitigating the repercussions of climate change on diseases affecting important crop commodities in Southeast Asia, for food security and environmental sustainability-A review. Frontiers in Sustainable Food Systems. 2023; 6.: 1-23. Available from: https://doi.org/10.3389/fsufs.2022.1030540. ), lo que condiciona el período de vida en la explotación comercial de muchos cultivares élites de esta gramínea. En el noroeste de Sao Paulo en Brasil se estima el 18,6 % de decrecimiento del rendimiento agrícola por las afectaciones de la pudrición roja en las plantaciones cañeras (66. Viswanathan R. Changing scenario of sugarcane diseases in India since introduction of hybrid cane varieties: Path travelled for a century. Journal of Sugarcane Research. 2018; 8(1): 1-35. Available from: https://www.researchgate.net/publication/304572467.). También influye en la calidad del jugo, disminuyendo el contenido de sacarosa, la pureza, los grados Brix y la azúcar comercial (77. Silva TC, Moreira SI, Felizardo LM, Martins RM, Suzuki AN, Faria, et al. Dry rot Caused by the complex Colletotrichum falcatum and Thielaviopsis paradoxa emerges as a key stalk disorder in newly expanded sugarcane plantations from northwestern São Paulo, Brazil. Agronomy. 2023; 13 (2729): 1-20. Available from: https://doi.org/10.3390/agronomy13112729.).

Los síntomas de la pudrición roja pueden presentarse tanto en las hojas como en los tallos de caña de azúcar (88. Ahmad Z, Asad M, Fatima A, Gul S, Tabassum S, Ismat B, et al. Molecular diagnosis of red rot of sugarcane in Pakistan and in vitro control of isolated pathogen using rhizobacteria. Plant Protection Science. 2023; 59(2): 124-133. Available from: https://doi.org/10.17221/45/2022-PPS.). En las primeras son de menor importancia: produciendo manchas alargadas en el haz del nervio central, de color rojo intenso al principio que evolucionan después a rojo café (99. Romero JV, Diaz AE. Recomendaciones tecnológicas para el mejoramiento del sistema productive de caña de azúcar para panela en el occidente de Nariño. Mosquera. Agrosavia. 2022. ISBN: 978-958-740-618-4. Available from: https://editorial.agrosavia.co/index.php/publicaciones/catalog/book/310 ,1010. Jernisha J, Poorniammal R, Sivakumar U, Harish S, Sethuraman K. Plant growth promoting microorganisms and emerging biotechnological approaches for sgarcane disease anagement. Journal of Pure and Applied Microbiology. 2024; 8(4): 2205-2217. Available from: https://doi.org/10.22207/JPAM.18.4.27.). Las lesiones pueden extenderse por todo el raquis en ambas direcciones del mismo, llegando a ocupar toda la nervadura (1111. Jernisha J, Poorniammal R, Sivakumar U, Harish S, Sethuraman K. Plant growth promoting microorganisms and emerging biotechnological approaches for sugarcane disease management. Journal of Pure and Applied Microbiology. 2024; 18(4): 2205-2217. Available from: https://doi.org/10.22207/JPAM.18.4.27.). En los tallos causa un cambio de color de los tejidos internos a rojo con pudriciones secas en los ápices (1212. Riaz S, Mustafa G, Khan MS, Abbas MA. Exploring mycoparasitic potential of indigenous Trichoderma strains for the effective control of red rot disease in sugarcane. Asian Asian J Agric & Biol. 2025; 1: 1-9. Available from: https://doi.org/10.35495/ajab.2024.136.,1313. Abdallah A, Batista JA, Maced N. Colletotrichum falcatum e complexo de espécies de Fusarium spp. na cana-de-açúcar: caracterização das doenças e estratégias de controle. Revista Caderno Pedagógico. 2024; 21(5): 1-21. Available from: https://doi.org/10.54033/cadpedv21n5-134.). La putrefacción en el interior de las plantas se caracteriza por la presencia de bandas blancas transversales en los tejidos infectados por C. falcatum (1414. Magarey R. Field guide diseases of australian sugarcane. Australia. Sugar Research Australia Limited. 2022. ISBN: 978-0-949678-43-0. Available from: https://scholar.google.com/scholar?q=related:r071rQlDNpEJ:scholar.google.com/&scioq=Field+guide+diseases+of+australian+sugarcane.+Australia.+&hl=es&as_sdt=0,5 -1616. Sharma AS, Kalia A, Sharma A, Sidhu MS, Sanghera GS, Chhabra G, et al. Expression of Trichoderma spp. endochitinase gene improves red rot disease resistance in transgenic sugarcane. PLOS ONE. 2024; 19(9): 1-21. Available from: https://doi.org/10.1371/journal.pone.0310306. ). Además, provoca la decoloración del follaje y de la corteza de los tallos, lo que conlleva a la muerte de las plantas y de los nuevos brotes en el plantón (1717. Viswanathan R. Red rot of sugarcane (Colletotrichum falcatum Went). CAB Reviews. 2021a; 16(23): 1-57. Available from: https://doi.org/10.1079/PAVSNNR202116023.,1818. Thineshkumar J1, Surendran1 K, IndianrajN. Recent advances in control of red rot in sugarcane-An overview. International Journal of Advanced Research in Science, Communication and Technology. 2023; 3(2): 193-196. Available from: https://doi.org/10.48175/IJARSCT-8378193. ).

La alta variabilidad genética de C. falcatum aumenta la virulencia del hongo en las plantas de caña de azúcar (1919. Hossain MI, Ahmad K, Vadamalai G, Siddiqui Y, Saad N, Ahmed OH, et al. Phylogenetic analysis and genetic diversity of Colletotrichum falcatum isolates causing sugarcane red rot disease in Bangladesh. Biology. 2021; 10; 862. Available from: https://doi.org/10.3390/biology10090862. ,2020. Cavalcanti FE, Santos MJ, Silva JM, Silva JRA, Costa JF, Feijó FM, et al. Colletotrichum species associated with sugarcane red rot in Brazil. Fungal Biology. 2022; 126(4): 290-299. Available from: https://doi.org/10.1016/j.funbio.2022.02.002.). Esta situación provoca la pérdida de la resistencia de los cultivares debido a las extensas plantaciones comerciales de esta gramínea que aumentan la exposición a este hongo, lo que pone en riesgo la durabilidad del cultivo (2121. Cursi DE, Hoffmann HP, Barbosa GVS, Bressiani JA, Gazaffi R, Chapola RG, et al. History and current status of sugarcane breeding, germplasm development and molecular genetics in Brazil. Sugar Technology. 2021; 24(1): 112-133. Available from: https://doi.org/10.1007/s12355-021-00951-1.). Sobre la base de las consideraciones anteriores el manejo de esta enfermedad a través de cultivares resistentes se dificulta (2222. Hossain MI, Ahmad K, Siddiqui Y, Saad N, Rahman Z, Haruna AO, et al. Curren and prospective strategies on detecting and managing Colletotrichum falcatum causing red rot of sugarcane. Agronomy. 2020; 10(1253):1-19. Available from: https://doi.org/10.3390/agronomy10091253.). Igualmente algunos autores señalan una interacción genotipo-ambiente-patógeno que influye en la incidencia y severidad de la pudrición roja y alertan sobre la erosión de la resistencia en los cultivares comerciales (2323. Ul-Hassan M, Walayat HM, Akhlaq M, Shahzad M, Yasin M, Muzaffar M, et al. Evaluation of new sugarcane genotypes for biometric traits, resistance to red rot and borers complex under agro-climatic conditions of Faisalabad, Pakistan. International Journal of Agriculture & Bbiology. 2020; 23(3): 623-629. ISSN: 1560-8530. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.cabidigitallibrary.org/doi/full/10.5555/20203268857 ,2424. Viswanathan R. Sustainable sugarcane cultivation in India through threats of red rot by varietal management. Sugar Technology. 2021b; 23: 239-253. Available from: https://doi.org/10.1007/s12355-020-00882-3. ).

En Pakistán se informa la reacción diferencial de los cultivares ante la pudrición roja en el germoplasma de caña de azúcar y cambios en la severidad de los síntomas (2525. Khan HMWA, Ul-Hassan M, Mudassir MA, Afzal MS, Yasin M, Ahmad MF, et al. Resistance to red rot disease (Colletotrichum falcatum) varies among different germplasm sources of sugarcane. International Journal of Agriculture & Biology. 2021; 25(2): 381-387. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.researchgate.net/figure/Resistance-of-sugarcane-genotypes-against-red-rot-disease_tbl3_339200131 ); mientras indican esta misma situación en clones y cultivares comerciales en la India (2626. Mahata G, Sardar S. Evaluation of elite sugarcane clones/varieties against red rot disease (Colletotrichum falcatum) and their suitability in crop improvement programme. Agricultural Science and Technology. 2022; 14(1): 28-33. Available from: https://doi.org/10.15547/ast.2022.01.004.,2727. Ravichandran V, Ganapathy S, Shanmuganathan M, Jayakumar J, Gayathry G, Saravanan PA, et al. Resistance of sugarcane clones (Saccharum spp.) to red rot disease (Collectorichum falcatum Went) and analysis of resistant clone by FTIR. International Journal of Plant & Soil Science. 2023; 35(18): 1250-1256. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://journalijpss.com/index.php/IJPSS/article/view/3391 ). En consecuencia, se hace necesario ratificar la estabilidad del comportamiento de los cultivares ante la enfermedad, por lo que el objetivo de este trabajo es determinar la severidad de Colletotrichum falcatum en patrones de resistencia de caña de azúcar.

Materiales y Métodos

El estudio se desarrolló en el bloque experimental del Instituto de Investigaciones de la Caña de Azúcar sobre un suelo Ferralítico Rojo típico (2828. Hernández A, Pérez JM, Bosch D, Castro N. Clasificación de los suelos de Cuba. La Habana. INCA-IS. 2015. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://ediciones.inca.edu.cu/files/libros/clasificacionsueloscuba_%25202015.pdf ); ubicado en las coordenadas georreferenciadas latitud norte: 22º 47´ 12´´ y longitud oeste: 82º 23´ 13´´, en el municipio Quivicán, provincia Mayabeque, Cuba.

Los experimentos se establecieron en parcelas formadas por un surco de 7,5 m de longitud y 1,6 m de ancho, sin réplicas. En estos se plantaron los cinco cultivares categorizados como patrones de resistencia a la pudrición roja de la caña de azúcar (´PR980´, altamente resistente; ´Ja60-5´, resistente; ´My5514´, moderadamente resistente; ´B4362´, susceptible; y ´C137-81´, altamente susceptible) (2929. Alfonso F, Montalván J, Casero T, Delgado J. Adecuación del sistema evaluativo de la resistencia a la pudrición roja del tallo de la caña de azúcar (Colletotrichum falcatum Went) en el programa de mejora de la caña de azúcar. Revista Cuba & Caña. 2016; 19(1): 1-4. ISSN: 1028-6527. Available from: https://www.cuba-cane.inica.azcuba.cu/index.php/cyc/article/view/66 ) en los meses de octubre de los años del 2014 al 2019. No se realizaron aplicaciones de fertilizantes y solamente se efectuaron tres riegos con normas de 250 m³ ha cada siete días a partir de la plantación para garantizar la brotación de las plantas.

En el tercer entrenudo basal de 25 tallos tomados al azar de cada cultivar a los 13 meses de edad (principio del mes de noviembre) se realizó una perforación con un punzón de 0,2 cm de diámetro y 2,0 cm de profundidad. En el interior del orificio se depositó con una jeringuilla 0,2 mL de una suspensión conidial de concentración 5 x 10⁵ ufc mL^-1 de C. falcatum procedente de plantas enfermas en condiciones naturales de ´C137-81´ del bloque experimental anteriormente mencionado. El inóculo se aisló en placas de Petri en los laboratorios de protección de plantas de las Unidades Empresariales de Base del Instituto de Investigaciones de la Caña de Azúcar en Camagüe y Santiago de Cuba, de donde se preparó la suspensión conidial con la de concentración anteriormente mencionada.

Tres meses y medio después de realizar la inoculación, se cortaron y se rajaron longitudinalmente los tallos. En la evaluación de los síntomas de la enfermedad se tuvieron los siguientes criterios: coloración; largo y ancho de la lesión; presencia, abundancia y características de las manchas blancas producidas por la infección; número de entrenudos infectados; cogollo verde, amarillo o muerto. La reacción de los cultivares se determinó utilizando la escala que teniendo en cuenta los anteriores criterios señalados (Tabla 1) (1717. Viswanathan R. Red rot of sugarcane (Colletotrichum falcatum Went). CAB Reviews. 2021a; 16(23): 1-57. Available from: https://doi.org/10.1079/PAVSNNR202116023.).

La severidad de la enfermedad en los cultivares se determinó teniendo en cuenta la reacción a C. falcatum de cada planta inoculada y se calculó según la siguiente expresión matemática (3030. Towsend GR, Heuberger JV. Methods for estimating losses caused by diseases in fungicide experiments. Plant Disease Report, 1943; 24: 340-343. Available from: https://www.scirp.org>reference..):

Donde:

SE: severidad de la enfermedad.

n: número de tallos infectados por cada grado de la enfermedad.

v: grado de la escala.

i: mayor grado de la escala.

N: total de muestras.

Las variables meteorológicas: precipitaciones, temperaturas mínimas, medias y máximas; así como la humedad relativa de los períodos enmarcados entre la inoculación del hongo y la evaluación de la severidad de la enfermedad, fueron recolectadas y procesadas en la Estación Güira de Melena del Instituto Nacional de Meteorología (INSMET) (Tabla 2). La misma se encuentra ubicada a 5 Km del lugar donde se estableció el experimento en el municipio Güira de Melena, provincia Artemisa.

En el procesamiento estadístico se empleó análisis de varianza (ANOVA) de clasificación simple y prueba de comparación de medias por Tukey (p<0,05), para comparar los porcentajes de severidad de la enfermedad en los cultivares evaluados y los años; además se efectuó un análisis de regresión lineal simple para relacionar los porcentajes de severidad de la enfermedad con las precipitaciones, temperaturas máximas, mínimas y medias, así como la humedad relativa (p<0,01); todo esto con la ayuda del paquete estadístico InfoStat, versión 2015.

Resultados y Discusión

La suspensión conidial de C. falcatum inyectada fue los suficiente virulenta para producir la enfermedad en los tallos de caña de azúcar inoculados (Figura 1). Los cultivares categorizados como patrones de resistencia a la pudrición roja alcanzaron los grados de infección propuestos para evaluar su resistencia y su estabilidad ente esta enfermedad (2929. Alfonso F, Montalván J, Casero T, Delgado J. Adecuación del sistema evaluativo de la resistencia a la pudrición roja del tallo de la caña de azúcar (Colletotrichum falcatum Went) en el programa de mejora de la caña de azúcar. Revista Cuba & Caña. 2016; 19(1): 1-4. ISSN: 1028-6527. Available from: https://www.cuba-cane.inica.azcuba.cu/index.php/cyc/article/view/66 ), lo que los ratifica como patrones en cada categoría de la escala.

Existen diferencias significativas en los porcentajes de la severidad de la enfermedad en cada cultivar categorizado como patrón de resistencia a la pudrición roja (p≤0,05) (Figura 2). La misma fluctuó desde 20 hasta el 100 %; en ´PR980´ fue de 20 %, en ´Ja60-5´ oscilo desde 34 hasta 52 %, en ´My5514´ de 38 al 58 %, en ´B4362´ estuvo del 42 al 70 % y en´ C137-81´ se movió desde el 70 al 100 %.

Los porcentajes de severidad promedio de C. falcatum en los cultivares empleados como patrones de resistencia mostraron diferencias significativas en los años de estudio (p≤0,05) (Figura 3). Los mayores valores se alcanzaron en 2014, 2015 y 2018 con una gran disminución en 2015 y 2016.

Los porcentajes de severidad promedios de la pudrición roja tienen poca relación con los valores de las precipitaciones (Figura 4), temperaturas mínimas (Figura 5), medias (Figura 6) y máximas (Figura 7); así como la humedad relativa en el período evaluado (2014-2019) (Figura 8). Esta situación pudiera estar relacionada con los estrechos rangos de variación de las variables meteorológicas en los meses trascurridos entre la infección del hongo y la evaluación de los síntomas en las plantas. Estos resultados corroboran a esta época del año como la propicia para la inoculación de C. falcatum en tallos de caña de azúcar para evaluar su comportamiento ante esta enfermedad.

Existen diferencias estadísticamente significativas en los porcentajes de severidad promedio de C. falcatum alcanzados en los cultivares empleados como patrones de resistencia a la pudrición roja en los períodos evaluados a pesar de que estos experimentos estuvieron poco influenciados por los valores de las variables meteorológicas. Sin embargo, en estudios efectuados en plantaciones comerciales de caña de azúcar se evidenció la influencia de la temperatura mínima entre 25,8 y 26,4 °C, humedad relativa en el rango de 70 a 90 % y las precipitaciones superiores a 30 mm mensualmente en el aumento de la incidencia de esta enfermedad (3131. Dubey S, Minnatullah MD, Maurya S, Chaudhary CS, Singh SP, Kumar B. Effect of weather parameters on incidence of red rot disease in sugarcane. Journal of Pharmacognosy and Phytochemistry. 2020; 9(2): 1053-1055. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.phytojournal.com/archives/2020.v9.i2.10993/effect-of-weather-parameters-on-incidence-of-red-rot-disease-in-sugarcane ).

En efecto, las precipitaciones y la humedad relativa son factores que favorecen la las condiciones para el desarrollo de la pudrición roja y que los porcentajes de incidencia más altos de esta enfermedad se detectaron en las regiones donde estos anualmente alcanzaron los valores más altos, 4387 mm y 85 % respectivamente (3232. Martínez IE, Perdomo LT, Sterling A, Hoyos JD. Intensidad de los síntomas de las principales patologías foliares presentes en 10 variedades de caña panelera (Saccharum spp) en dos zonas agroecológicas del Departamento de Caquetá (2019). Scientia et Technica. 2021; 26(3): 343-352. ISSN: 0122-1701. Available from: https://elibrary.ru/item.asp?id=74259545 ). También se informa el papel vital de las variables meteorológicas, particularmente las precipitaciones y las temperaturas en el desarrollo de C. falcatum al aumentar la severidad de la infección con temperaturas ente 23 y 24°C (mínima), 34 y 37 °C (máxima), y un alto régimen pluviométrico (3333. Viswanathan R, Selvakumar R, Manivannan K, Nithyanantham R, Kaverinathan K. Behaviour of soil borne inoculum of Colletotrichum falcatum in causing red rot in sugarcane varieties with varying disease resistance. Sugar Technology. 2020; 22(3): 485-497. Available from: https://doi.org/10.1007/s12355-020-00800-7.,3434. Atiq M, Akram A, Ahmed N, Nawaz A, Usman M, Jabbar A, et al. Management tactics towards red rot; cancer of sugarcan-a review. Journal of Xi’an Shiyou University, Natural Science Edition. 2023; 19(06): 263-281. ISSN: 1673-064X. Available from: https://www.xisdxjxsu.asia/viewarticle.php?aid=2360 ).

Las precipitaciones favorecen la diseminación e infección del hongo en las plantas; mientras que las temperaturas más propicias para el desarrollo de la enfermedad están entre los 29 y 31°C, con valores de humedad relativa superiores al 85 % (3535. Shukla P, Kumarm A, Kumarm M, Raghuvanshi HR, Kumar A, Mishra PK. Red rot disease (Colletotrichum falcatum) of sugarcane and their integrated management. Just Agriculture. 2022; 3(4): 1-4. ISSN: 2582-8223. Available from: https://justagriculture.in/files/newsletter/2022/december/42.%20Red%20Rot%20Disease%20%28Colletotrichum%20falcatum%29%20of%20Sugarcane%20and%20their%20Integrated%20Management.pdf ). En este sentido (3636. Salotti I, Ji T, Rossi V. Temperature requirements of Colletotrichum spp. belonging to different clades. Frontiers in Plant Science. 2022; 13: 1-20. Available from: https://doi.org/10.3389/fpls.2022.953760.) señalan que las temperaturas mínimas para que se produzca la infección por C. falcatum son 15°C, mientras que las optima es de 30 °C.

Conclusiones

Introduction

Red rot of the stalk, caused by Colletotrichum falcatum Went (conidial state) [= Glomerella tucumanensis (Spegazzini) Von Arx and E. Müller], is a widely distributed disease in areas where sugarcane (Saccharum spp.) is cultivated in the tropics (11. Olahan GS, Fatoba PO, Balogun OS. Incidence of smut and red rot diseases of sugarcane in southern part of niger state, north central Nigeria. Science World Journal. 2021; 15(2): 73-75. ISSN: 1597-6343. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.scienceworldjournal.org/article/view/20545/13637 ). In Cuba, it is among the diseases detected since 1915, with a wide dispersion in sugarcane plantations of sugar companies (22. Chinea A, Zayas E, Bruner S. Inventario de enfermedades de la caña de azúcar en Cuba: tercera etapa. Revista Cuba & Caña. 2019;22(3):8-14. ISSN: 1028-6527. Available from: https://scholar.google.com/scholar?hl=es&as_sdt=0%2C5&q=Inventario+de+enfermedades+de+la+ca%C3%B1a+de+az%C3%BAcar+en+Cuba%3A+tercera+etapa&btnG= ,33. Mayorga SA, Centeno SP, Toapanta OG, Haro YE. Efecto de Colletotrichum falcatum en los parámetros productivos de caña de azúcar, revisión integral y estrategias de manejo. Polo del Conocimiento. 2025; 10(7): 280-301. Available from: https://doi.org/10.23857/pc.v10i7.9889.).

The disease causes severe damage to sugarcane plants (44. Kurian JA, Jehani M, Mohamed JM, Vaja S. Assessment and management of diverse isolates of Colletotrichum falcatum associated with red rot disease in sugarcane. International Journal of Research in Agronomy. 2024; 7(7): 417-425. Available from: https://doi.org/10.33545/2618060X.2024.v7.i7e.1062.,55. Ann J, Syafawati J, Mohd SRA, Edwina J, Ali H, Shah MR. Mitigating the repercussions of climate change on diseases affecting important crop commodities in Southeast Asia, for food security and environmental sustainability-A review. Frontiers in Sustainable Food Systems. 2023; 6.: 1-23. Available from: https://doi.org/10.3389/fsufs.2022.1030540. ), which affects the commercial lifespan of many elite cultivars of this grass. In the northwestern region of São Paulo, Brazil, an 18.6 % decrease in agricultural yield has been estimated due to the effects of red rot in sugarcane plantations (66. Viswanathan R. Changing scenario of sugarcane diseases in India since introduction of hybrid cane varieties: Path travelled for a century. Journal of Sugarcane Research. 2018; 8(1): 1-35. Available from: https://www.researchgate.net/publication/304572467.). It also influences juice quality, reducing sucrose content, purity, Brix degrees, and commercial sugar (77. Silva TC, Moreira SI, Felizardo LM, Martins RM, Suzuki AN, Faria, et al. Dry rot Caused by the complex Colletotrichum falcatum and Thielaviopsis paradoxa emerges as a key stalk disorder in newly expanded sugarcane plantations from northwestern São Paulo, Brazil. Agronomy. 2023; 13 (2729): 1-20. Available from: https://doi.org/10.3390/agronomy13112729.).

Symptoms of red rot can occur on both leaves and stalks of sugarcane (88. Ahmad Z, Asad M, Fatima A, Gul S, Tabassum S, Ismat B, et al. Molecular diagnosis of red rot of sugarcane in Pakistan and in vitro control of isolated pathogen using rhizobacteria. Plant Protection Science. 2023; 59(2): 124-133. Available from: https://doi.org/10.17221/45/2022-PPS.). On leaves, they are of lesser importance, producing elongated spots on the upper side of the midrib, initially intense red in color, later turning reddish-brown (99. Romero JV, Diaz AE. Recomendaciones tecnológicas para el mejoramiento del sistema productive de caña de azúcar para panela en el occidente de Nariño. Mosquera. Agrosavia. 2022. ISBN: 978-958-740-618-4. Available from: https://editorial.agrosavia.co/index.php/publicaciones/catalog/book/310 ,1010. Jernisha J, Poorniammal R, Sivakumar U, Harish S, Sethuraman K. Plant growth promoting microorganisms and emerging biotechnological approaches for sgarcane disease anagement. Journal of Pure and Applied Microbiology. 2024; 8(4): 2205-2217. Available from: https://doi.org/10.22207/JPAM.18.4.27.). Lesions may extend along the entire rachis in both directions, eventually occupying the entire midrib (1111. Jernisha J, Poorniammal R, Sivakumar U, Harish S, Sethuraman K. Plant growth promoting microorganisms and emerging biotechnological approaches for sugarcane disease management. Journal of Pure and Applied Microbiology. 2024; 18(4): 2205-2217. Available from: https://doi.org/10.22207/JPAM.18.4.27.). On stalks, they cause a color change of internal tissues to red, with dry rot at the tips (1212. Riaz S, Mustafa G, Khan MS, Abbas MA. Exploring mycoparasitic potential of indigenous Trichoderma strains for the effective control of red rot disease in sugarcane. Asian Asian J Agric & Biol. 2025; 1: 1-9. Available from: https://doi.org/10.35495/ajab.2024.136.,1313. Abdallah A, Batista JA, Maced N. Colletotrichum falcatum e complexo de espécies de Fusarium spp. na cana-de-açúcar: caracterização das doenças e estratégias de controle. Revista Caderno Pedagógico. 2024; 21(5): 1-21. Available from: https://doi.org/10.54033/cadpedv21n5-134.). Internal putrefaction of plants is characterized by the presence of transverse white bands in tissues infected by C. falcatum (1414. Magarey R. Field guide diseases of australian sugarcane. Australia. Sugar Research Australia Limited. 2022. ISBN: 978-0-949678-43-0. Available from: https://scholar.google.com/scholar?q=related:r071rQlDNpEJ:scholar.google.com/&scioq=Field+guide+diseases+of+australian+sugarcane.+Australia.+&hl=es&as_sdt=0,5 -1616. Sharma AS, Kalia A, Sharma A, Sidhu MS, Sanghera GS, Chhabra G, et al. Expression of Trichoderma spp. endochitinase gene improves red rot disease resistance in transgenic sugarcane. PLOS ONE. 2024; 19(9): 1-21. Available from: https://doi.org/10.1371/journal.pone.0310306. ). Furthermore, it causes discoloration of the foliage and stalk rind, leading to plant death and the death of new shoots in the stool (1717. Viswanathan R. Red rot of sugarcane (Colletotrichum falcatum Went). CAB Reviews. 2021a; 16(23): 1-57. Available from: https://doi.org/10.1079/PAVSNNR202116023.,1818. Thineshkumar J1, Surendran1 K, IndianrajN. Recent advances in control of red rot in sugarcane-An overview. International Journal of Advanced Research in Science, Communication and Technology. 2023; 3(2): 193-196. Available from: https://doi.org/10.48175/IJARSCT-8378193. ).

The high genetic variability of C. falcatum increases the virulence of the fungus on sugarcane plants (1919. Hossain MI, Ahmad K, Vadamalai G, Siddiqui Y, Saad N, Ahmed OH, et al. Phylogenetic analysis and genetic diversity of Colletotrichum falcatum isolates causing sugarcane red rot disease in Bangladesh. Biology. 2021; 10; 862. Available from: https://doi.org/10.3390/biology10090862. ,2020. Cavalcanti FE, Santos MJ, Silva JM, Silva JRA, Costa JF, Feijó FM, et al. Colletotrichum species associated with sugarcane red rot in Brazil. Fungal Biology. 2022; 126(4): 290-299. Available from: https://doi.org/10.1016/j.funbio.2022.02.002.). This situation causes the loss of cultivar resistance due to the extensive commercial plantations of this grass, which increase exposure to this fungus, thus jeopardizing crop durability (2121. Cursi DE, Hoffmann HP, Barbosa GVS, Bressiani JA, Gazaffi R, Chapola RG, et al. History and current status of sugarcane breeding, germplasm development and molecular genetics in Brazil. Sugar Technology. 2021; 24(1): 112-133. Available from: https://doi.org/10.1007/s12355-021-00951-1.). Based on the aforementioned considerations, the management of this disease through resistant cultivars is difficult (2222. Hossain MI, Ahmad K, Siddiqui Y, Saad N, Rahman Z, Haruna AO, et al. Curren and prospective strategies on detecting and managing Colletotrichum falcatum causing red rot of sugarcane. Agronomy. 2020; 10(1253):1-19. Available from: https://doi.org/10.3390/agronomy10091253.). Likewise, some authors point to a genotype-environment-pathogen interaction that influences the incidence and severity of red rot and warn about the erosion of resistance in commercial cultivars (2323. Ul-Hassan M, Walayat HM, Akhlaq M, Shahzad M, Yasin M, Muzaffar M, et al. Evaluation of new sugarcane genotypes for biometric traits, resistance to red rot and borers complex under agro-climatic conditions of Faisalabad, Pakistan. International Journal of Agriculture & Bbiology. 2020; 23(3): 623-629. ISSN: 1560-8530. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.cabidigitallibrary.org/doi/full/10.5555/20203268857 ,2424. Viswanathan R. Sustainable sugarcane cultivation in India through threats of red rot by varietal management. Sugar Technology. 2021b; 23: 239-253. Available from: https://doi.org/10.1007/s12355-020-00882-3. ).

In Pakistan, the differential reaction of cultivars to red rot in sugarcane germplasm and changes in symptom severity have been reported (2525. Khan HMWA, Ul-Hassan M, Mudassir MA, Afzal MS, Yasin M, Ahmad MF, et al. Resistance to red rot disease (Colletotrichum falcatum) varies among different germplasm sources of sugarcane. International Journal of Agriculture & Biology. 2021; 25(2): 381-387. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.researchgate.net/figure/Resistance-of-sugarcane-genotypes-against-red-rot-disease_tbl3_339200131 ); while this same situation is indicated in clones and commercial cultivars in India (2626. Mahata G, Sardar S. Evaluation of elite sugarcane clones/varieties against red rot disease (Colletotrichum falcatum) and their suitability in crop improvement programme. Agricultural Science and Technology. 2022; 14(1): 28-33. Available from: https://doi.org/10.15547/ast.2022.01.004.,2727. Ravichandran V, Ganapathy S, Shanmuganathan M, Jayakumar J, Gayathry G, Saravanan PA, et al. Resistance of sugarcane clones (Saccharum spp.) to red rot disease (Collectorichum falcatum Went) and analysis of resistant clone by FTIR. International Journal of Plant & Soil Science. 2023; 35(18): 1250-1256. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://journalijpss.com/index.php/IJPSS/article/view/3391 ). Consequently, it is necessary to confirm the stability of cultivar behavior against the disease. Therefore, the objective of this study is to determine the severity of Colletotrichum falcatum on sugarcane resistance patterns.

Materials and Methods

The study was conducted in the experimental block of the Sugarcane Research Institute on a typical Red Ferrallitic soil (2828. Hernández A, Pérez JM, Bosch D, Castro N. Clasificación de los suelos de Cuba. La Habana. INCA-IS. 2015. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://ediciones.inca.edu.cu/files/libros/clasificacionsueloscuba_%25202015.pdf ), located at the georeferenced coordinates North Latitude: 22° 47' 12'' and West Longitude: 82° 23' 13'', in the municipality of Quivicán, Mayabeque province, Cuba.

The experiments were established in plots consisting of a single row 7.5 m in length and 1.6 m in width, without replicates. Five cultivars categorized as resistance patterns to sugarcane red rot were planted ('PR980', highly resistant; 'Ja60-5', resistant; 'My5514', moderately resistant; 'B4362', susceptible; and 'C137-81', highly susceptible) (2929. Alfonso F, Montalván J, Casero T, Delgado J. Adecuación del sistema evaluativo de la resistencia a la pudrición roja del tallo de la caña de azúcar (Colletotrichum falcatum Went) en el programa de mejora de la caña de azúcar. Revista Cuba & Caña. 2016; 19(1): 1-4. ISSN: 1028-6527. Available from: https://www.cuba-cane.inica.azcuba.cu/index.php/cyc/article/view/66 ) during the months of October from 2014 to 2019. No fertilizer applications were made, and only three irrigations were carried out with norms of 250 m³ ha⁻¹ every seven days after planting to ensure plant sprouting.

The third basal internode of 25 randomly selected stalks from each cultivar at 13 months of age (early November) was perforated with a 0.2 cm diameter, 2.0 cm deep punch. Into the hole, 0.2 mL of a conidial suspension of C. falcatum at a concentration of 5 × 10⁵ CFU mL⁻¹ was deposited using a syringe. The inoculum was obtained from diseased plants of 'C137-81' under natural conditions from the aforementioned experimental block. The inoculum was isolated in Petri dishes at the plant protection laboratories of the Basic Business Units of the Sugarcane Research Institute in Camagüey and Santiago de Cuba, where the conidial suspension was prepared at the aforementioned concentration.

Three and a half months after inoculation, the stalks were cut and split longitudinally. For disease symptom evaluation, the following criteria were considered: coloration; length and width of the lesion; presence, abundance, and characteristics of white spots produced by infection; number of infected internodes; and green, yellow, or dead terminal bud. Cultivar reaction was determined using a scale that considered the aforementioned criteria (Table 1) (1717. Viswanathan R. Red rot of sugarcane (Colletotrichum falcatum Went). CAB Reviews. 2021a; 16(23): 1-57. Available from: https://doi.org/10.1079/PAVSNNR202116023.).

Disease severity in the cultivars was determined based on the reaction to C. falcatum of each inoculated plant and was calculated using the following mathematical expression (3030. Towsend GR, Heuberger JV. Methods for estimating losses caused by diseases in fungicide experiments. Plant Disease Report, 1943; 24: 340-343. Available from: https://www.scirp.org>reference..):

Where:

SE: disease severity

n: number of stalks infected for each disease rating

v: rating on the scale

i: highest rating on the scale

N: total number of samples

The meteorological variables: rainfall, minimum, average, and maximum temperatures, as well as relative humidity for the periods between fungal inoculation and disease severity evaluation, were collected and processed at the Güira de Melena Station of the National Institute of Meteorology (INSMET) (Table 2). This station is located 5 km from the site where the experiment was established, in the municipality of Güira de Melena, Artemisa province.

Statistical analysis was performed using a single-classification ANOVA and Tukey's test (p < 0.05) to compare disease severity percentages among cultivars and years. A simple linear regression analysis was also conducted to relate disease severity percentages to rainfall, maximum, minimum, and mean temperatures, and relative humidity (p < 0.01). All analyses were carried out using InfoStat statistical software, version 2015.

Results and Discussion

The injected conidial suspension of C. falcatum was sufficiently virulent to produce disease in the inoculated sugarcane stalks (Figure 1). The cultivars categorized as resistance patterns to red rot achieved the infection levels proposed to evaluate their resistance and stability against this disease (2929. Alfonso F, Montalván J, Casero T, Delgado J. Adecuación del sistema evaluativo de la resistencia a la pudrición roja del tallo de la caña de azúcar (Colletotrichum falcatum Went) en el programa de mejora de la caña de azúcar. Revista Cuba & Caña. 2016; 19(1): 1-4. ISSN: 1028-6527. Available from: https://www.cuba-cane.inica.azcuba.cu/index.php/cyc/article/view/66 ), thus confirming them as pattern cultivars for each category of the scale.

For statistical analysis, a single-classification analysis of variance (ANOVA) and Tukey's mean comparison test (p < 0.05) were used to compare disease severity percentages among the evaluated cultivars and across years. Additionally, a simple linear regression analysis was performed to relate disease severity percentages to rainfall, maximum, minimum, and mean temperatures, as well as relative humidity (p < 0.01). All analyses were conducted using the statistical software package InfoStat, version 2015.

Significant differences (p ≤ 0.05) were observed in disease severity percentages for each cultivar categorized as a resistance pattern to red rot (Figure 2). Severity ranged from 20 to 100 %. For 'PR980', it was 20 %; for 'Ja60-5', it ranged from 34 to 52 %; for 'My5514', from 38 to 58 %; for 'B4362', from 42 to 70 %; and for 'C137-81', from 70 to 100 %.

The average severity percentages of C. falcatum in the cultivars used as resistance patterns showed significant differences across the study years (p ≤ 0.05) (Figure 3). The highest values were reached in 2014, 2015, and 2018, with a marked decrease in 2015 and 2016.

Mean red rot severity percentages were poorly correlated with rainfall (Figure 4), minimum (Figure 5), mean (Figure 6), and maximum temperatures (Figure 7), as well as relative humidity (Figure 8) during the 2014-2019 evaluation period. This may be attributed to the narrow range of variation in meteorological variables during the months between fungal inoculation and symptom assessment. These findings confirm that this time of year is suitable for C. falcatum inoculation in sugarcane stalks to evaluate their response to the disease.

Statistically significant differences were observed in the average severity percentages of C. falcatum reached in the cultivars used as resistance patterns to red rot across the evaluated periods, even though these experiments were weakly influenced by the values of the meteorological variables. However, studies conducted in commercial sugarcane plantations demonstrated the influence of minimum temperatures between 25.8 and 26.4 °C, relative humidity in the range of 70 to 90 %, and monthly rainfall exceeding 30 mm on the increased incidence of this disease (3131. Dubey S, Minnatullah MD, Maurya S, Chaudhary CS, Singh SP, Kumar B. Effect of weather parameters on incidence of red rot disease in sugarcane. Journal of Pharmacognosy and Phytochemistry. 2020; 9(2): 1053-1055. Available from: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.phytojournal.com/archives/2020.v9.i2.10993/effect-of-weather-parameters-on-incidence-of-red-rot-disease-in-sugarcane ).

Indeed, rainfall and relative humidity are factors that favor the conditions for red rot development, and the highest incidence percentages of this disease were detected in regions where these factors annually reached the highest values, 4387 mm and 85 %, respectively (3232. Martínez IE, Perdomo LT, Sterling A, Hoyos JD. Intensidad de los síntomas de las principales patologías foliares presentes en 10 variedades de caña panelera (Saccharum spp) en dos zonas agroecológicas del Departamento de Caquetá (2019). Scientia et Technica. 2021; 26(3): 343-352. ISSN: 0122-1701. Available from: https://elibrary.ru/item.asp?id=74259545 ). The vital role of meteorological variables, particularly rainfall and temperatures, in the development of C. falcatum is also reported, as infection severity increases with temperatures between 23 and 24 °C (minimum), 34 and 37 °C (maximum), and a high rainfall regime (3333. Viswanathan R, Selvakumar R, Manivannan K, Nithyanantham R, Kaverinathan K. Behaviour of soil borne inoculum of Colletotrichum falcatum in causing red rot in sugarcane varieties with varying disease resistance. Sugar Technology. 2020; 22(3): 485-497. Available from: https://doi.org/10.1007/s12355-020-00800-7.,3434. Atiq M, Akram A, Ahmed N, Nawaz A, Usman M, Jabbar A, et al. Management tactics towards red rot; cancer of sugarcan-a review. Journal of Xi’an Shiyou University, Natural Science Edition. 2023; 19(06): 263-281. ISSN: 1673-064X. Available from: https://www.xisdxjxsu.asia/viewarticle.php?aid=2360 ).

Rainfall enhances the dissemination and infection of the fungus in plants, while the most favorable temperatures for disease development are between 29 and 31 °C, with relative humidity values above 85 % (3535. Shukla P, Kumarm A, Kumarm M, Raghuvanshi HR, Kumar A, Mishra PK. Red rot disease (Colletotrichum falcatum) of sugarcane and their integrated management. Just Agriculture. 2022; 3(4): 1-4. ISSN: 2582-8223. Available from: https://justagriculture.in/files/newsletter/2022/december/42.%20Red%20Rot%20Disease%20%28Colletotrichum%20falcatum%29%20of%20Sugarcane%20and%20their%20Integrated%20Management.pdf ). In this regard, it has been noted that the minimum temperature for C. falcatum infection to occur is 15 °C, while the optimum temperature is 30 °C (3636. Salotti I, Ji T, Rossi V. Temperature requirements of Colletotrichum spp. belonging to different clades. Frontiers in Plant Science. 2022; 13: 1-20. Available from: https://doi.org/10.3389/fpls.2022.953760.).

Conclusions