Integrated proposal for management of root rot caused by Phytophthora cinnamomi in avocado cv. Hass crops

Abstract

Phytophthora cinnamomi is the most important pathogen in avocado crops that causes the disease named avocado root rot (PRR). This disease affects the root system and induces multiple symptoms that end with plant death and causes large economic losses. PRR management is based almost exclusively on the use of fungicides (metalaxyl and phosphites). This situation led to inefficient management practices with apparently satisfactory results only in short periods. The objective of this work was to evaluate different PRR management practices under in vitro, net house and field conditions. The initial part of the study was carried out under in vitro and net house conditions evaluating different types of ions (boron, zinc and manganese chelate), the auxin α naphthaleneacetic, fungicides (potassium phosphite, fosetyl aluminium and metalaxyl) and microorganisms associated with biological control of diseases. For field conditions, the most promising strategies were selected, which included fungicide use (rotation of metalaxyl and phosphites), organic matter in the form of residues of vegetables and mushrooms, use of foliar (manganese) and soil (calcium, magnesium, phosphorus, and silicon) ions, additions of bovine manure, beneficial microorganisms (Rizoglomus fasciculatum, Trichoderma sp., and Bacillus sp.), edaphic application of auxin and an energy source (sucrose). Results indicated that individual control methods of PRR are not sustainable over time. However, the implementation of a disease integrated management program including several strategies of control proved to be effective for PRR. At the same time that PRR was satisfactorily managed, the economic sustainability was achieved and it was possible to reduce the reliance on phosphonate applications.