Infection of olive trees by Heterodera mediterranea in orchards in southern Spain

High infection rates of olive feeder roots and soil infestation by the cyst -forming nematode Heterodera mediterranea were found in commercial olive or chards cv. Manzanilla established in sandy soils at two localities of Sevil la Province of Andalucia, southern Spain. No disease symptoms were noted on the aboveground plant parts, but slightly distorted feeder roots and necro tic areas were observed near the infection points. Sedentary juvenile stage s and adult females showed a semi-endoparasitic feeding habit. Histopatholo gical studies of infected olive roots showed a disease response typical of cyst nematode infection of susceptible hosts. Nematode feeding induced sync ytial formation involving cellular alterations in the cortex, endodermis, p ericycle, and vascular parenchyma tissues in both cortical and endodermal r oot cells.