Molecular Pathogens 2024, Vol.15, No.5, 227-236 http://microbescipublisher.com/index.php/mp 230 4 Diagnostic Techniques for Bacterial Diseases 4.1 Field-based visual diagnosis Field-based visual diagnosis involves the identification of disease symptoms directly in the field. This method is often the first step in diagnosing bacterial diseases in sugarcane. However, it has significant limitations, particularly for diseases like Ratoon Stunting Disease (RSD), which do not exhibit distinct external symptoms, making visual diagnosis challenging and often unreliable (Young et al., 2016; Chakraborty et al., 2023; Krishna et al., 2023). For instance, bacterial leaf wilt caused by Pantoea stewartii subsp. stewartii can be identified by symptoms such as leaf blade bleaching, blight, and necrotic lesions, but these symptoms can be confused with other stress factors (Cui et al., 2020). 4.2 Molecular diagnostic tools Molecular diagnostic tools have revolutionized the detection of bacterial pathogens in sugarcane. Techniques such as Polymerase Chain Reaction (PCR) and quantitative PCR (qPCR) are widely used due to their high sensitivity and specificity. For example, PCR-based methods have been developed for detecting pathogens responsible for diseases like RSD, leaf scald, and gumming disease (Srivastava et al., 2016; Viswanathan et al., 2018; Krishna et al., 2023). The use of isothermal amplification techniques, such as Loop-Mediated Isothermal Amplification (LAMP), has also been optimized for on-site diagnostics, allowing for rapid and accurate detection of pathogens like Leifsonia xyli subsp. xyli in crude cane juice at sugar mills (Burman et al., 2023). These molecular tools are essential for large-scale disease surveillance and management. 4.3 Serological and immunological methods Serological and immunological methods, including enzyme-linked immunosorbent assay (ELISA) and immunofluorescence, are used to detect bacterial pathogens based on antigen-antibody interactions. These methods are particularly useful for detecting pathogens in asymptomatic plants. Evaporative-binding enzyme immunoassay (EB-EIA) coupled with phase contrast microscopy (PCM) has been used to detect Leifsonia xyli subsp. xyli in sugarcane xylem sap (Liang, 2024). Although these methods can be highly specific, they often require sophisticated laboratory equipment and trained personnel, which can limit their use in field conditions. Nonetheless, they remain valuable tools for confirming diagnoses made by other methods (Viswanathan et al., 2018). 5 Control Measures for Bacterial Diseases 5.1 Chemical control strategies 5.1.1 Use of antibiotics and chemicals Chemical control strategies for bacterial diseases in sugarcane often involve the use of antibiotics and chemical treatments. These methods aim to reduce the bacterial load and prevent the spread of pathogens. For instance, certain chemicals have been used to manage diseases like red rot caused by Colletotrichum falcatum(Hossain et al., 2020). However, the effectiveness of these treatments can vary, and their application must be carefully managed to avoid resistance development and environmental harm. 5.1.2 Challenges of chemical control in sugarcane The use of chemical control in sugarcane faces several challenges. One major issue is the potential for environmental pollution and disruption of soil microbial flora due to excessive and long-term application of chemical fertilizers and pesticides (Singh et al., 2021). Additionally, the high cost and labor-intensive nature of chemical treatments can be prohibitive for many farmers. There is also the risk of developing resistant strains of pathogens, which can render chemical treatments ineffective over time (Chakraborty et al., 2023). 5.2 Biological control approaches 5.2.1 Beneficial microbes as biocontrol agents Biological control approaches utilize beneficial microbes to combat bacterial diseases in sugarcane. Endophytic bacteria, such as those from the genus Bacillus, have shown promise in controlling pests and diseases by colonizing plant tissues and producing antimicrobial compounds (Rocha et al., 2021). Similarly, rhizosphere
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