SOIL TEXTURE AND SUPPRESSIVENESS EFFECT OF PATHOGENIC POTENTIAL OF Fusarium oxysporum f. sp. cepae ON ONION (Allium cepa L.)

Supresividad del suelo al potencial patogénico de Fusarium oxysporum

Abstract

In Mexico, onion (Allium cepa L.) production es affected by phytopathogenic fungi, with Fusarium oxysporum f. sp. cepae standing out as the cause of basal rot in this crop. It exhibits a high capacity for reproduction, survival, and dissemination, making it essential to study its behavior in relation to soil texture in order to design control strategies with lower environmental impact. The aim of this study was to evaluate the effect of different soil textures on the suppressiveness of pathogenic potential (severity and reproduction) of F. oxysporum f. sp. cepae in onion crop. Soil samples from six textural classes were used and placed in previously disinfected plastic containers. Eighteen onion plants were planted per container with two treatments: one inoculated with Fusarium and the control treatment, non-inoculated (each soil texture corresponded to one treatment, and each treatment included three replicates). The Disease Severity Index (DSI) was evaluated on onion plants and bulbs, as well as the density or reproduction of the pathogen through Colony Forming Units (CFU) in soil textures. The greatest suppressive effect of the soil was observed in loam, sandy loam, and clay loam soils, which exhibited lower DSI, with values of 4.17, 6.25 and 8.33% for plants and 0.362, 0.481 and 0.619% for bulbs, respectively, as well as lower pathogenic potential against Fusarium. The soils with silty loam and silty textures showed the lowest suppressiveness and highest pathogenic potential toward Fusarium.