Pine wilt disease (PWD) caused by the pine wood nematode (PWN) is China’s most serious forest disease in recent decades. Its complex disease system with unclear pathogenesis and differentiated pathogenicity makes it challenging to manage and control. PWD has spread rapidly in Northeast and Northwest China in recent years, exceeding previous predictions and the traditional understanding of its potential distribution. This paper reviewed the comprehensive risk of PWD in Northeast and Northwest China through the occurrence of influencing factors. Regarding PWN’s temperature resistance, all regions of China are suitable for PWD. In terms of altitude, the PWD system is mainly distributed below 1000 m. In China, Pinus and Larix species are confirmed host trees of PWN, while Monochamus alternatus and M. saltuarius are confirmed vector insects of PWN. In this case, PWD may occur in all low-altitude pine forests in China. Northeast China has a higher risk than Northwest China due to its distribution of suitable host trees and vector beetles at low altitudes. To confront the threat, two scientific bottlenecks are required to be demonstrated. The first is the pathogenicity of Chinese PWN strains to Chinese Picea and Abies species. The other is the geographical distribution and highest altitude distribution of other Monochamus species in the Palaearctic region of China and their PWN transmission ability. We also suggest strengthening plant quarantining in Northeast China. In conclusion, this review comprehensively analyzes the risk of PWD in Northeast and Northwest China in terms of temperature, altitude, host trees, and vector insects. It provides a new perspective and reference for the management and research of PWD in China.

Bursaphelenchus xylophilus (pine wood nematode, PWN) has been present in China for over 40 years and has spread to northeast China, where native pine species are key components of the local top community. Pinus thunbergii is known to be susceptible to PWN among local conifer species, whereas research on PWN’s pathogenicity in Larix remains limited. Furthermore, there are no research reports on PWN infestation in Picea and Abies species within China. This study conducted a detailed analysis of phenotypic changes and temporal spectral reflectance variations in four conifer species in northeast China—P. thunbergii, Larix kaempferi, Picea koraiensis, and Abies holophylla—following artificial inoculation with PWN. The aim of this study is to establish a theoretical basis for identifying the potential hosts and threats of PWN. The study incorporated a 60-day post-inoculation observation period to systematically monitor and compare temporal changes in external morphology, disease susceptibility (incidence and mortality rates), spectral reflectance, and the normalized wilt index (NWI) in 2–3-year-old seedlings of P. thunbergii, L. kaempferi, P. koraiensis, and A. holophylla after inoculation with PWN. The results showed that P. thunbergii displayed the earliest infection symptoms, followed by L. kaempferi, A. holophylla, and finally P. koraiensis. After inoculation, P. thunbergii was the first to experience mortality, followed by L. kaempferi, P. koraiensis, and A. holophylla. Following inoculation, P. thunbergii exhibited the earliest significant increase in NWI (p < 0.001), followed by L. kaempferi and A. holophylla; P. koraiensis showed the latest increase (p < 0.001). In conclusion, the experiment identified P. koraiensis as having the strongest resistance to PWN among the four species, followed by A. holophylla. P. thunbergii showed the weakest resistance, while L. kaempferi exhibited moderate resistance. The ranking of PWN susceptibility for the four conifer species, from highest to lowest, is as follows: P. thunbergii, L. kaempferi, A. holophylla, and P. koraiensis.