Variation in resistance of loblolly pine (Pinus taeda L.) families against Leptographium and Grosmannia root fungi

摘要

Pine decline poses a serious threat to forest sustainability in the south-eastern United States. Complex interactions between biotic and abiotic factors are involved in the decline and include root-feeding bark beetles and their associated fungal genera, Leptographium and Grosmannia. A study was conducted to determine the relative tolerance of loblolly pine (Pinus taeda L.) families when challenged with either Leptographium or Grosmannia species. In the first study, bare root seedlings from 23 loblolly pine families were screened with L. procerum, L. terebrantis, G. huntii and G. alacris using an artificial inoculation method. In a second study, containerized seedlings from 27 loblolly pine families were screened with G. huntii and L. terebrantis. Measured seedling responses to the inoculations included lesion length, lesion width and occlusion of vascular tissues, measured 8 weeks after inoculations. The most common host response was dark brown lesions and resinous occluded stem tissue. Seedling families had a wide range of host responses to the different Leptographium and Grosmannia species and showed that it could be possible to select the families that may be tolerant to Leptographium and Grosmannia fungal species based on these results.