Cultural, morphological, pathogenic and isoenzymatic charaterization of Colletotrichum gloeosporioides Penz. isolates causing anthracnose on avocado ( Persea americana Mill.) in Michoacán, México

Orchard phytosanitary inspections of avocado cv. Hass in different agroecological zones of Michoacán, Mexico revealed symptoms variability attributed to Colletotrichum gloeosporioides Penz. The objective was to detect variants of C. gloeosporioides by morphological, cultural, isoenzymatic and pathogenic criteria. Fruits of avocado cv. Hass were collected with anthracnose symptoms, with glossy brown surface spots with cracks in the lesion in the municipalities of Uruapan, San Juan Nuevo, Tancítaro, Peribán and Tacambaro in Michoacan, Mexico. The fungus C. gloeosporioides Penz was isolated from Hass avocado fruits but Pestalotiopsis versicolor (Speg.) Steyart was also isolated from similar spots. Fruits at the physiological maturation stage were most susceptible to C. gloeosporioides infection. C. gloeosporioides variants were determined from 42 monoconidial cultures, based in the following criteria: 1. Cultural: a) by the shape and color of the colony: 11 variants (v), b) by the growth rate of the colony: 19 v; 2. Morphological: a) by the conidial size: 23 v., b) by the conidial shape: 4 v.; 3. Pathogenic: a) diameter of the lesions 9 v.; b) firmness of the lesion: 6 v.; c) weight of the damaged flesh: 3 v.; d) susceptibility to cooper oxiclorure, maneb, thiabendazol and benomyl: 17, 23, 5 and 7 v. respectively. 4. Isoenzymatic: a) by isoenzymes 14 v. were differentiated, three of them were outstanding (two presented a difference of 50% and one in 25% of the loci studied). Municipality Uruapan presented the greatest number of C. gloeosporioides variants, followed by San Juan Nuevo. Inspecciones fitosanitarias de huertos de aguacate cv. Hass en las diferentes zonas agroecológicas de Michoacán revelan variabilidad de síntomas atribuidos a Colletotrichum gloeosporioides Penz. El objetivo fue detectar variantes de C. gloeosporioides mediante criterios morfológicos, culturales, patogénicos e isoenzimáticos. Se colectaron frutos de aguacate cv. Hass con síntomas de antracnosis, de viruela, con manchas superficiales café brillante y con cuarteaduras en la lesión en los municipios de Uruapan, San Juan Nuevo, Tancítaro, Peribán y Tacámbaro en Michoacan, México. El hongo C. gloeosporioides fue aislado de frutos de aguacate cv. Hass pero Pestalotiopsis versicolor (Speg.) Steyart también fue aislado de síntomas similares a los de antracnosis. Frutos en la etapa fenológica de madurez fisiológica fueron los más susceptibles a la infección de C. gloeosporioides. Se determ