Evaluation of genetic resistance in Pinus to pitch canker in Spain

Pitch canker is a disease that affects pines in many countries throughout the world. Fusarium circinatum, the causal agent of pitch canker, has recently been reported in Europe, where it is regulated as a quarantine pest. This pathogen represents a substantial threat to natural Pinus forests and plantations. To date, two mating types of F. circinatum have been described, both of which are present in Spain. To assess the potential risk of F. circinatum to Pinus in Spain, the main conifer species grown in Spain, namely Pinus sylvestris , P. nigra, P. pinaster, P. radiata , P. halepensis P. pinea and P. uncinata , were examined for their susceptibility to four Spanish isolates of F. circinatum. Two-year-old shoots were wounded and then inoculated with the four Spanish isolates, and lesion lengths were measured 2 weeks after inoculation. Pinus radiata was found to be the most susceptible species to the Spanish isolates, whereas P. pinea, P. halepensis, P. nigra, P. uncinata and P. pinaster were found to be relatively resistant and showed a significantly different lesion size from P. radiata. For P. pinaster, variations in resistance were found between provenances. One particular provenance (Meseta Castellana) was found to be more resistant than the three other provenances tested. No differences in virulence between the Mat-1 and Mat-2 isolates were detected. Overall, the low susceptibility of all native species to pitch canker suggests a moderate potential risk to the Spanish natural forests and a high potential risk to the exotic forestry of P. radiata.