States of phenological development of avocado (Persea americana Mill.) based on the BBCH scale extended and its relationship to the incidence of anthracnose in field conditions

Mexico is the main producer and exporter of avocado (Persea americana Mill) worldwide. However, despite the importance and high production, in Latin America the phenology of the crop has not yet been analyzed based on the extended BBCH scale (BBCH abbreviation derived from the following German institutions Biologische Bundesanstalt, Bundessortenamt and Chemische Industrie) and its relationship with anthracnose, which is the most important fungal disease in avocado production that can economically limit production and reduce fruit quality. The objective of this work was to apply the extended BBCH scale to describe the phenological stages of avocado in the state of Morelos and relate the incidence of anthracnose in each of the phenological stages. Phenology studies periodic biological events in relation to seasonal variations of climatic conditions, so it was demonstrated in the development of this research that under the climatic conditions of Morelos state, specifically in the study areas, avocado presented two stages of vegetative growth in summer and winter colloquially called as normal flowering (Mesostage 1) and local flowering (Mesostage 2), and 7 of the 10 main stages of growth were observed, starting with the development of the buds and ending in the development of the fruit. Likewise, there are variables that directly influence the development of the crop and the appearance of anthracnose symptoms in the field. Relative humidity has a positive correlation with the incidence of the disease under field conditions, while average temperature has a negative correlation with the incidence of anthracnose symptoms under field conditions. It was also determined that the incidence of anthracnose during the study period was highest in June, July and August, with lower levels in December to April. With this information it is possible to homogenize the different phenological stages of avocado and establish strategies that positively influence the integrated management of avocado cultivation in all producing areas of the country.