Susceptibility study of avocado varieties to the attack of mistletoe in Michoacán

Abstract

Parasitic mistletoe caused infestations in wild and commercial perennials are one of the principal limiting factors of production and the cause of high mortality rates. The objective was to study the susceptibility of different avocado materials to infestation of mistletoe species and to identify the genres and species of mistletoe that grow in the diversity of avocado trees that coexists in the avocado productive region of Michoacan. It was sampled a fraction of this region and botanic material from the parasitic plants in avocado was collected. In vivarium and in avocado plants from ‘Hass’, ‘Fuerte’ and ‘criollo’ varieties, infestations were induced with the mistletoe seeds collected in situ. Three to four seeds were placed in each avocado plant with an experimental design of completely randomized blocks, with six repetitions. The response was observed for a year as far as sprouting rate and development of hemiparasitic endophyte tissue on the infected plants. Three genres and four species were registered parasitizing avocado trees (Persea americana Mill. var. drymifolia). The results of the induced infestation of mistletoe from the P. calyculatus specie had highly significant difference (Pr>F=0.0024) for the development of endophytic tissue of the parasitic plant in the different avocado materials. The greater incidence was in the ‘criollo’ variety with an 83.3% of the plants developing haustorium of the hemiparasite on the host steam. The ‘fuerte’ avocado variety presented