Resistance to pitch canker disease, caused by Fusarium subglutinans f.sp. pini, in Monterey pine (Pinus radiata)

Fusarium subglutinans f.sp. pini causes pitch canker, resulting in branch d ieback and stem cankers, in many species of pine, Monterey pine has suffere d extensive damage from pitch canker in both urban and native forests in Ca lifornia. The extent of lesion development differed significantly among Mon terey pine individuals subjected to mechanical inoculations under field and glasshouse conditions. Lesion lengths resulting from inoculations of the s ame clone at different times or in different locations were highly correlat ed. The eight strains of F. s. pini known to occur in California did not in teract differentially with the Monterey pine clones tested. Trees with limi ted lesion development did not sustain girdling lesions or branch dieback a nd hence may be considered resistant to pitch canker.