Need for control of Phytophthora root disease of cork oaks at Doñana National Park (south-western Spain).

Abstract

The current oak population at Doñana National Park consist of big scattered individuals representing a 10% of the forest that occupied the area for three centuries. After the protection of the area as Biological Reserve, cutting, pruning and cork extraction ceased, but cork oak population is suffering a quick decline that threatens their survival. The main menace to cork oaks comes from the high density of herbivores which eat the acorns and prevent seedlings to grow. Additionaly, the oaks occupied by wading birds during the nesting season show signs of stress (defoliation), and die much faster than trees not occupied. Soil under the trees, accumulating faeces, is increasing its salinity, becoming incompatible with oak survival. Last year we detected the sudden death of mature trees, which die within a few months independently to the presente of nesting birds. Seven foci of Phytophthora cinnamomi root disease have been detected. The exceptionally rainy winter of 2009-2010 lead to an unusual waterlogging at Doñana, increasing the risk of disease spreading all along the Reserve. In fact, it is expected an increment in the number and size of foci. Phosphonate treatment by trunk injection have been proposed to the Park authorities. 2009-2010 lead to an unusual waterlogging at Donana, increasing the risk of disease spreading al1 along the Reserve. In fact, it is expected an increment in the number and size of foci. Phosphonate treatment by trunk injection have been proposed to the Park