Soil Characterization of Cavendish Farms Infected and Non-Infected With FOC TR4 in Davao Del Norte, Southern Philippines

Abstract

In Mindanao, hectares of Cavendish banana are threatened by Panama disease caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (FOC) Tropical Race 4 (TR4), which cannot be controlled using fungicides and fumigants. FOC TR4 can survive for decades in the soil. Hence, it threatens the million-dollar banana export industry and the livelihoods of people who depend on it. In this study, we determined the physical, chemical and biological properties of soil from FOC-infected and FOC-free banana farms in Sto. Tomas, Davao del Norte, Philippines. Both farms vary in their physical characteristics as indicated in the soil textural analysis. In both farms,  magnesium and zinc are more than the standard level, organic matter is below standards, and the soil pH is slightly acidic. We observed two pathogenic bacteria colonies from the infected soil sample and one colony from the uninfected sample. However, we did not observe the fungi Fusarium oxysporum and Ralstonia solanacearum in the samples but found Penicillium sp. Root growth status was observed to be comparable in both infected and non-infected soils. In terms of plant parasitic nematodes, we found high populations of Helicotylenchus sp. in the roots and low populations of Radopholus sp., Meloidogyne sp. and Hoplolaimus sp. We also did not detect organophosphate, carbamate, pyrethroid and glyphosate chemicals in both soil samples. Low soil organic matter, low % clay and high% sand may imply suppression of soil organic dynamics. It may play a crucial role in the persistence of FOC TR4 in the soil.