Effectiveness of soil management practices on Fusarium wilt of banana in the Ribeira Valley, Brazil

Fusarium oxysporum f.sp. cubense (Foc), the causal agent of Fusarium wilt of banana (FWB), is doubtless the most challenging pathogen of this crop. In Brazil, FWB caused a dramatic shift from the susceptible cultivars “Maçã” (AAB) and “Prata” (AAB) to Cavendish (AAA) cultivars, which are resistant to local Foc populations. Management practices to reduce yield losses due to FWB in these cultivars would improve returns to growers serving this market, while also building knowledge to cope with other Foc populations, such as tropical race 4, still not present in Brazil. In this study, a set of soil management practices aiming to reduce FWB intensity, enhance soil health, and increase productivity were evaluated in the banana cultivar “Prata Catarina” (Pome, AAB). A field trial was established in a naturally Foc-infested area where three alternative treatments (T1, T2, T3) and a control were compared during three cropping cycles. In the T3 treatment, Ca(NO₃)₂ and heat-treated rock phosphate were applied as sources of N and P, together with 3 t ha⁻¹ of compost at planting plus 12 t ha⁻¹ of compost per year. T1 and T2 treatments were variations of the T3 treatment. Control plots followed the local practices of the banana growers. Regardless of the treatment, the first symptoms of FWB were observed at the flowering stage. The average FWB incidence was > 90% higher in the control than in the treatments in the first cropping cycle. However, the effectiveness of the treatments on reducing FWB decreased gradually in the second and third cycles. Soil analyses revealed a significant impact in the pH, Ca availability, and base saturation, which were higher in the treatments (T1, T2, T3) than in the control. Plant nutrition was not significantly altered by treatments, except for Ca content, which was lower in the control than in the treatments. The average yield of three cycles was 14% greater in the alternative treatments than in the control. Our results also indicate that the soil management practices tested in this study were not enough to cope with FWB. Further studies testing additional practices, such as reducing initial pathogen inoculum load at pre-planting, early detection, and eradication of infected plants, should also be conducted to verify its applicability as part of integrated FWB management packages.