Resumen en inglés

The yam crop is of great importance for the economy of tropical and subtropical countries located in Africa, Asia, Central and South America, and is part of the human diet, being valued for its contribution of carbohydrates and vitamins. The most widely planted species have been affected by phytosanitary problems caused by fungi and viruses, where the most limiting disease is anthracnose (Colletotrichum gloeosporioides), causing losses of up to 85%. Disease management has been done through the application of fungicides and cultural practices without achieving an effective management of the disease; due to the lack of knowledge of the disease and the increasing levels of resistance of the genus to different fungicides, in this sense, the monitoring of resistance to fungicides is crucial to achieve an effective management of the disease and no previous report has explored the resistance in the populations of Colletotrichum in yams in Colombia. Therefore, the following research was conducted to evaluate the sensitivity of Colletotrichum spp. to fungicides with different modes of action. The research was carried out in two phases, one in the field and the other in the laboratory; in the field, the different symptoms associated with anthracnose were identified and described, then isolates of each type of lesion were obtained and the macroscopic and microscopic characteristics of the isolates were described. The virulence and severity of the isolates was determined by in vitro inoculation of four promising accessions of yam D. alata and three of D. rotundata. Genetic variability was determined by sequencing the ITS region of the 5,8S gene. Finally, the sensitivity of the strains to fungicides was determined by in vitro assays. Field observations allowed the classification of nine types of symptoms in yam cultivars (seven lesions and two necroses). Eleven monosporic isolates were obtained and classified into three groups according to morphological and cultural characteristics, with a correlation coefficient r = 0.90, which showed differences between pathogenicity and virulence in resistant and susceptible hosts. Partial sequencing of the ITS region identified C. gloeosporioides and C. fructicola associated with yam anthracnose in the department of Córdoba. Disease severity showed statistical differences, allowing the classification of accessions as highly resistant, resistant and highly susceptible. Finally, the sensitivity of the isolates according to LD50 values, azoxystrobin and difenoconazole were most effective against the isolates of Colletotrichum spp, tested in this study, followed by chlorothalonil and captan, while the least effective fungicides were mancozeb and benomyl. This research confirmed the variability in symptomatology, morphological and molecular traits, virulence and fungicide sensitivity of Colletotrichum spp. associated with yam anthracnose, which can be exploited to improve disease management strategies.