OCCURRENCE AND PATHOGENICITY OF PYTHIUM SPP IN THE DUST DEPOSITED ON THE GREENHOUSE ROOFS IN THE PONIENTE REGION OF ALMERIA SOUTHEAST SPAIN
J. Sánchez, J.S. Olivares, E. Gallego
Dust accumulated on greenhouse roofs can be an important source of inoculum of Pythium spp. for the crops developing within. During the period March-May 1998, 20 greenhouses in the horticultural Poniente region of Almería (South-East Spain) were sampled monthly. Pythium isolates were cultured from the greenhouse dust. The density of the Pythium population was measured in the dust from 5 of these greenhouses, and the pathogenicity of 7 isolates was determined. Four species were identified and described: Pythium aphanidermatum, P. catenulatum, P. mamillatum and P. spinosum. This is the first report of P. spinosum for Spain. The mean total Pythium population densities ranged from 60 to 3450 propagules g-1 (d. wt) of greenhouse dust. All the isolates tested were pathogenic. The most pathogenic were the P. aphanidermatum isolates.