Intraspecies variation of maturePinus taedain response to root‐infecting ophiostomatoid fungi

Summary Seedling screening studies have shown intraspecies variation in susceptibility ofPinus taeda(loblolly pine) toLeptographium terebrantisandGrosmannia huntii, the causal agents of root infection inPinusspecies. However, it is critical to understand the susceptibility of matureP. taedatrees. Roots of matureP. taedafamilies determined as susceptible and tolerant toL. terebrantisandG. huntiiby previous seedling screening trials were artificially inoculated with the same fungal isolates. Dark necrotic lesion and vascular occlusion were recorded 8 weeks later. Families previously considered as susceptible had relatively longer lesions and occlusions. The variation in susceptibility to the two fungi remained the same as exhibited by families in the seedling trial. These results suggest intraspecies variation in relative susceptibility ofP. taedatoL. terebrantisandG. huntiiremains similar regardless of the age of the tree.