Factors affecting egg hatch of Heterodera mediterranea and differential responses of olive cultivars to infestation.

The influence of temperature and olive root exudates on Heterodera mediterranea egg hatch and the effects of H. mediterranea on the growth of two olive cultivars (Arbequina and Picual) were investigated. Egg hatch occurred over a temperature range of 10 to 30 degrees C and was optimal at 20 to 25 degrees C. There were no differences in egg hatch between sterile deionized distilled water or root exudate dilutions (undiluted, diluted 1:1, and 1:2) of Arbequina and Picual at 20 degrees C. Heterodera mediterranea reproduced on both olive cultivars in growth chambers at 25 degrees C. Soil and root final nematode populations, as well as total number of cysts per plant and reproduction rate, were significantly higher in Arbequina than in Picual. Shoot dry and root fresh weights as well as increases of shoot height, trunk diameter, and numbers of nodes were significantly suppressed by infection with 10,000 eggs + second-stage juveniles/pot in Arbequina but not in Picual.