Fusarium wilt (Foc Race 1) in relation to soil properties in smallholder’s farms with ‘gros Michel’ banana (Musa AAA) in Costa Rica

Summary

The aim of the study was to understand the relationship between soil properties and Fusarium wilt (FW) by Foc Race 1 in banana cv. ‘Gros Michel’. The experimentation was based on soils from the Turrialba region in Costa Rica. A first analysis took place under greenhouse conditions with Foc Race 1 inoculated plants and grown in two representative soil types from the region. The disease expression in relation with two soil pH levels (lower than 5.0 and higher than 6.0) and three weekly N doses (low: 0.00 g plant-1, medium: 0.08 g plant-1 and high: 0.25 g plant-1) applied with an ammonium nitrate solution in water. Soil type, pH and their interactions significantly affected the disease, where plants grown in the lower pH showed a higher FW expressed as a lower biomass. A second analysis used information at 20 farms in the region, where 49 fields were studied. FW expressed as a Severity Index (SI) was measured. Besides, agroecological variables such as altitude, slope, annual rainfall, average temperature, and soil fertility were determined. In addition, management variables as plant density and soil cover were gathered. A higher SI of FW was linked with a lower organic matter (SOM), and a higher acidity, calcium, and magnesium concentration in the soil. Other agroecological and management evaluated variables were not linked with the SI of FW. Given the fact that soil properties were highly correlated, it is difficult to attribute differences in SI of FW to individual soil properties. Each case should be considered as independent; however, results provide new insights into the relationship Soil-FW in banana. Practices of soil management such as liming, SOM founds application, and an adequate nutrient package are important options to alleviate the impact of the disease in the midterm in banana regions with Foc infested soils.