Sugarcane (Saccharum officinarum L.) is a perennial grass of the Poaceae family, extensively grown for its juice, which serves as the primary raw material for sugar production. This adaptable crop flourishes in tropical and subtropical regions of India and holds significant economic importance. Besides its pivotal role in sugar production, sugarcane plays a crucial part in the biofuel sector, where it is utilized for ethanol production. According to the FAO's 2021 report, the leading sugarcane-producing countries include Brazil, India, Thailand, Pakistan, Mexico, and Australia. India emerges as a significant global player in sugarcane cultivation, covering an expansive area of 48.7 million hectares. The impressive productivity of sugarcane was notable during the 2021–2022 periods, with the country's production surpassing 500 million metric tonnes (Anon., 2022a). A crucial contributor to this achievement is Punjab, where sugarcane holds pivotal importance as a cash crop. In 2022, Punjab achieved substantial yields, producing a total of 6.6 million metric tonnes on 0.92 million acres of land (Anon., 2022b).
Sugarcane growers face a myriad of challenges in production, resulting in significant losses due to both living organisms and environmental factors. Environmental challenges such as droughts, floods, typhoons, extreme heat, frost, and poor soil fertility greatly affect crop yields (Talukder et al., 2000). Additionally, sugarcane is susceptible to various pathogenic microorganisms including fungi, bacteria, viruses, mycoplasma, and nematodes (Rao et al., 2002). Among these, red rot caused by Colletotrichum falcatum Went (also known as Glomerella tucumanensis (Speg.) V. Arx and E. Muller in its perfect stage) consistently threatens sugarcane cultivation across different regions in the country (Viswanathan et al., 2002). Severe outbreaks of this disease can lead to extensive damage in the fields and complete loss of crops, often referred to as the 'Cancer' of sugarcane (Khan et al. 2011). This ailment not only reduces yield but also diminishes the quality of commercial cane sugar and sugarcane juice, highlighting the urgent need for effective management strategies.
In 1893, Went documented the emergence of red rot disease in Java (now part of Indonesia). He attributed the pathogen to Colletotrichum falcatum Went. The devastating impact of red rot was particularly notable in India between 1895 and 1899, affecting the Red Mauritius cultivar in the Godavari delta of the Madras Presidency (Barber, 1901). This disease subsequently spread throughout tropical India, causing significant crop damage and resulting in the rejection of several commercial varieties such as CoJ 64, CoJ 82, CoJ 84, and CoJ 1148 within the region (Viswanathan 2010). Identification of Colletotrichum falcatum involves detailed examination of its distinct morphological and cultural characteristics, including acervuli with setae, presence or absence of a teleomorph, colony color, sporulation patterns, and mycelium growth (Viswanathan et al, 2003).
Managing red rot in sugarcane has long been recognized as a challenging task. Pathogen virulence is influenced by environmental factors, plant genotypes, and the presence of aggressive pathogens. Current management strategies primarily focus on agricultural methods aimed at reducing pathogen prevalence in fields. Given the complexity of the issue, relying on a single approach is ineffective. Therefore, integrated disease management (IDM) is essential in the sugarcane industry (Agnihotri 1996; Ghazanfar et al. 2017).
The primary objective of IDM techniques is to mitigate the risks of red rot during replanting while simultaneously enhancing sugarcane yields. IDM includes a variety of practices such as cultural methods, the use of disease-free setts, resistant varieties, physical interventions, biological control, and chemical measures. These practices have been shown to significantly improve growth parameters and enhance sugarcane quality by reducing the prevalence of red rot compared to non-IDM techniques.
Implementing integrated disease management techniques has become indispensable for successful sugarcane cultivation in India and other countries. This research aims to achieve two objectives: i) assess various isolates of Colletotrichum falcatum for morphological, cultural, and pathogenic variability, and ii) evaluate the management of these isolates through in vitro testing using integrated disease management protocols.