Nondestructive evaluation of pathogenicity of Cercospora agavicola on agave azul tequilero plantlets irradiated with gamma rays Co60

Abstract

Agave crop and tequila industry have cultural, economic and social impact do to employment offered under Agro and industrial fields. Besides, currencies obtained by exportation. Fungal agave disease caused by C. agavicola represents high risk in the Altos zone in Jalisco, since environmental conditions favour incidence and severity of disease. Inoculation was carried out on plantlets obtained from axillary buds culture and irradiated by gamma rays Co⁶⁰: 0 Gy, 5 Gy, 10 Gy, 15 Gy, 20 Gy, 25 and 30 Gy. Constituting and experiment involving 7 treatments with 5 replicates each. Samples were collected from plants showing blight symptoms in the field. Fungus was isolated, grown and purified onto PDAA (for its acronym in spanish) medium at 25 °C. Subsecuently, fungus was inoculated directly onto leafs of Agave plantlets in Petri dishes containing moist filter paper in a suspension solution of 20 000 spores/mL^–1; all material was transferred onto sterile Petri dishes. Size (mm²) of lesions was evaluated 21 days later. Lesion size decrease as the irradiation dose increased. Lesions were classified into 3 groups: 0 Gy and 5 Gy greater than 90% of leaf area affected, 10 Gy and 15 Gy between 60% and 80% of leaf area affected and 20 Gy, 25 Gy and 30 Gy less 20% of leaf area affected. Pathogenicity tests should be corroborated on 6 months old plants with hardened and thick leaves.