Diseases and disorders associated with different stages of crop development and factors that determine the incidence in Hass avocado crops

Abstract

co. Diseases and disorders associated with different stages of crop development and factors that determine the incidence in Hass avocado cropsHass avocado production systems in Colombia have increased to become the third largest area planted for fruit production. A number of factors that limit productivity such as diseases have become of high economic importance. The objectives of this study were to identify the causal agents associated with pathologies in Hass avocado crops in different stages of development and to determine main environmental factors associated with their incidence. This work was conducted over a period of eight years (2009-2016), during which plots and nurseries were monitored. Results showed that the most common disease of Hass avocado was avocado wilt complex (AWC) caused mainly by Phytophthora cinnamomi. In addition, it was found that pathogens such as Lasiodiplodia theobromae, Colletotrichum gloeosporioides sensu lato, and Phytophthora palmivora, can affect diverse tissues of avocado plants, appearing in different stages of crop development. Incidence of different pathologies in commercial plots were influenced by technological level, the sampling season (rainy and dry), and environmental and topographical variables such as precipitation, slope and elevation. This work presented a holistic approach for analysis of pathologies in Hass avocado crops, which were determined by the stage of crop development, environmental and topographic variability and the technological level of the productive system.

Journal of Plant Protection Research

“…Pathogens were diagnosed via a polyphasic approach. Suitable symptomatic descriptions were included, supplemented by laboratory analysis with isolation protocols as described by Ramírez-Gil et al (2014). Morphological identifications were based on taxonomic codes for fungi genotypes reported by Barnett and Hunter (1972), and Seifert et al (2011), and Erwin and Ribeiro (1996 for Phytophthora species.…”

“…In addition, all microorganism that were positive were re-isolated. For hypoxia-anoxia conditions in roots, the guidelines reported by Ramírez-Gil et al (2014) were followed, planting seedlings in pots with a moisture regime in soil greater than 70%…”

“…The avocado wilt complex is considered to be the most limiting disease of this crop, affecting both roots and stems. This disease is associated with several pathogens, of which Phytophthora cinnamomi Rands is considered to be the most important (Zentmyer 1980(Zentmyer , 1984Ramírez-Gil et al 2014, 2017Hardham and Blackman 2018;Ramírez-Gil 2018). However, other causal agents, such as Verticillium sp., other Phytophthora spp., and an abiotic hypoxia-anoxia condition, can induce similar symptoms in roots and stems (Zentmyer 1984;Ramírez-Gil et al 2014).…”

“…This disease is associated with several pathogens, of which Phytophthora cinnamomi Rands is considered to be the most important (Zentmyer 1980(Zentmyer , 1984Ramírez-Gil et al 2014, 2017Hardham and Blackman 2018;Ramírez-Gil 2018). However, other causal agents, such as Verticillium sp., other Phytophthora spp., and an abiotic hypoxia-anoxia condition, can induce similar symptoms in roots and stems (Zentmyer 1984;Ramírez-Gil et al 2014). Hypoxia--anoxia is an abiotic disorder associated with soil moisture, which reduces the gas content in the porous space in soil volume, especially oxygen.…”

“…Avocado is susceptible to low levels of oxygen which can induce root rot. At the same time it favors pathogens such as P. cinnamomi infection (Stolzy et al 1967;Ramírez-Gil et al 2014;Sanclemente et al 2014).…”