Effect of Straw Removal and Irrigation Systems on the Community of Pathogenic Organisms

Resumo

Introduction: Soilborne pathogenic microorganisms are responsible for significant productivity losses in various crops, including sugarcane. Pathogens such as Fusarium oxysporum, Pythium sp., and Rhizoctonia solani can cause severe diseases in plant roots and vascular systems, compromising growth and yield. Straw removal and different irrigation systems can influence the dynamics of these pathogens in the soil, altering their abundance and impact on crops. Objective: This study aimed to evaluate the influence of straw removal and irrigation systems on the community of pathogenic organisms in sugarcane areas. Methodology: The experiment was conducted in sugarcane fields in the Goianésia region, Goiás, Brazil. Soil samples were collected from areas with different straw removal regimes (one and two years) and irrigation systems (sprinkler, pivot, and rainfed). The presence and abundance of pathogens, such as Fusarium oxysporum, Pythium sp., and Rhizoctonia solani, were determined using isolation and microbiological identification techniques. Data were statistically analyzed to verify significant differences between treatments. Main Results: The results indicated that areas without straw removal had the lowest concentrations of Fusarium oxysporum, while areas with sprinkler irrigation and one year of straw removal showed the highest amounts of this pathogen. Pythium sp. was most prevalent in rainfed areas with two years of straw removal, suggesting that the absence of organic cover can favor root pathogen development. However, an inverse correlation was observed between pathogen presence and beneficial organisms, such as Trichoderma spp., indicating a potential natural biocontrol effect. Conclusion: Straw removal significantly influences the presence of soil pathogens, with areas without straw removal showing lower levels of Fusarium oxysporum and Pythium sp.. The protective effect of straw against pathogens can be partially explained by the presence of beneficial organisms that suppress pathogens. Therefore, management practices that promote straw retention and the use of beneficial microorganisms can reduce the impact of pathogens in agricultural systems.