Evaluacion de la patogenicidad y agresividad de aislados de Neopestalotiopsis sp. Y Fusarium sp. asociados a la pudrición de corona de frutilla (Fragaria ananassa Duch.), en invernadero.

Abstract

This investigation aims to evaluate the level of pathogenicity and aggressiveness of the fungi Fusarium sp. and Neopestalotiopsis sp. causing crown rot in healthy strawberry plants in greenhouses. The process was carried out by the reactivation of the two fungal isolates cultivated on PDA medium for 7 days. After this time, the strains of Fusarium sp. and Neopestalotiopsis sp. were cultivated on SNA medium for 15 days for the preparation of the inoculum (conidial suspensions). After the mycelium was cultivated in SNA medium, 10 mL of distilled water was added and immediately the mycelium surface was gently scraped until a spore suspension was obtained. Finally, it is proceeded to count the fungal isolates to adjust their concentration to 1x105. The inoculation of the plants was carried out by the puncture method consisting of injecting 5 mL of inoculum in the upper part of the crown directly into the meristematic zone using sterile syringes, and the suspension method consisting of placing 50 mL of inoculum in the substrate around the crown of the strawberry plant. Plants inoculated by the puncture method by the fungus Neopestalotiopsis sp. showed external symptoms (necrotic spots, blackening of the petiole, wilting of the plant) and internal symptoms (rotting and necrosis of the crown tissues), proving to be pathogenic. Plants inoculated by Fusarium sp. species were not pathogenic, and it was tested by the absence of symptoms at the level of the flat phylum by the two inoculation methods. It is recommended to carry out studies for the evaluation of antagonists for biological and chemical control.