Susceptibility of six pine species to Gremmeniella abietina isolates from Spain

Inoculation experiments were performed in order to evaluate the virulence of Gremmeniella abietina isolates from Spain on the main pine species planted in the Iberian Peninsula, as well as the influence of seedling age on this virulence. Two different experiments were carried out with four isolates of G. abietina from Spain. The greenhouse experiments consisted of seedling inoculations. One- and 2-year-old seedlings of the following five pine species were used: Pinus halepensis, Pinus pinea, Pinus pinaster, Pinus sylvestris and Pinus uncinata; also, 1-year-old seedlings of P. nigra were inoculated. The relative necrosis length (RNL) caused by the pathogen after 130 days was used as a response variable. The laboratory experiments were performed on 2- to 6-year-old internodes of the above pine species excluding P. uncinata. The necrosis length after 6 weeks of incubation was measured. The results have shown that all G. abietina isolates were pathogens on seedlings of these six pine species and seedlings of P. halepensis were consistently the most susceptible ones, although it is important to take into account that all the isolates used in the present work were isolated from P. halepensis, the only pine species in Spain where G. abietina has been recovered up to now. The susceptibility of the other pine species depended on the age of the seedlings.