Dual-energy X-ray CT-scanning may detect butt rot in Norway spruce

Root- and butt rot caused by Heterobasidion spp. is a major cause of value loss in spruce round timber. It’s difficult to detect even with advanced round timber scanners. This pilot study investigated whether state-of-the-art CT could improve detection. Segments representing different visual stages of butt rot were sampled from a single Picea abies log. Pathogenic tests confirmed Heterobasidion spp. infection. Samples were scanned with a clinical photon-counting CT system, generating dual-energy and monoenergetic images. Segments exhibiting visual decay showed a localised dual-energy signal enhancement adjacent to the rot. This pattern was not detectable in monoenergetic images of segments with early decay. In segments with advanced decay, the dual-energy pattern was particularly pronounced at the heartwood-sapwood transition zone. In summary, the dual-energy images exhibited features likely related to butt rot.