Abstract

ALVARADO-ROSALES, Dionicio; SAAVEDRA-ROMERO, Luz de L.  and  ALMARAZ-SANCHEZ, Alejandra. First report of Phytophthora cinnamomi Rands: Associated with oak (Quercus spp.) in Tecoanapa, Guerrero, México. Agrociencia [online]. 2008, vol.42, n.5, pp.565-572. ISSN 2521-9766.

In our study it is reported the primary association of Phytophthora cinnamomi Rands. with massive death of oaks (Quercus spp.) first observed in 2001 in the municipality of Tecoanapa, Guerrero. This pseudo-fungus was isolated from cortical tissue (20 isolates) from trees with dieback and dark colored exudates at the trunk base, and from soil (18 isolates) in Barranca Colorada and Cerro del Amparo, Xalpatláhuac; Plan de Palemón, Magueyitos; and Huerta de Agustín, San Francisco. The camelloid cultural characteristics, torulose mycelia, and average sporangium dimensions (48.24x31.47 µm) were typical of P. cinnamomi. The greatest damage was observed in Q. salicifolia and Q. elliptica, and lower degrees of damage in Q. magnoliifolia, while Q. glaucescens is apparently resistant. Percentage of dieback in crowns of 189 oaks were traces (48.14%), slight (17.4%), and moderate (10%). Severe damage was observed in 10% of the oaks. This is the first report of P. cinnamomi associated with Q. salicifolia, Q. elliptica, and Q. magnoliifolia in the state of Guerrero.

Keywords : Phytophthora cinnamomi; Quercus spp.; Tecoanapa.