Evaluación de la patogenicidad de tres aislados de Fusarium spp. asociados con el sistema radicular en mora (Rubus glaucus Benth), en invernadero.

Abstract

The objective of this research was to evaluate the pathogenicity and aggressiveness level of the fungi Fusarium oxysporum, Fusarium solani, and Fusarium redolens associated with crown rot in healthy blackberry plants in greenhouses. The process started with the reactivation of the three fungal isolates grown on a PDA medium for seven days, then for inoculum preparation, (conidial suspensions) the strains were cultivated in a V8 liquid medium (bacteriological agar, distilled water, calcium carbonate, and V8 vegetable juice) for seven days at 26 °C in the orbital shaker-incubator. After the mycelium was cultured, it was sieved to separate the spores from the mycelium and obtain a spore suspension. Finally, it was proceeded to count the fungal isolates, thus allowing it to adjust their concentration to 1x106 propagules/mL. Inoculation was carried out through two methods. Inoculation was by means of damage to the root system plus root immersion in the inoculum suspension, which consisted of immersing the plant free of the sheath in the inoculum suspension for 3 minutes and returning to the same sheath with the substrate, the method of inoculation by drenching to the substrate consisted of placing 20 ml of inoculum in the substrate around the crown of the blackberry plant. Plants inoculated by the immersion method by the three strains showed external symptomatology (wilting of the plant, necrotic spots from the edge of the leaves) and internal symptomatology (slight rotting of the crown tissues and necrosis of the absorbing hairs) showing that all the inoculated strains were pathogenic. Plants inoculated by the drench method showed more severe symptomatology, plant death, and drying from old and young leaves. It is recommended to study biological controls with the studied strains of Fusarium spp.