The impacts of global trade on the dispersal of fungal trunk pathogens in nursery stock

An increasing amount of grapevine plant material, nursery plants and breeding stock, is moving vast distances, resulting in an increased risk of pathogen introduction into new areas. One of the primary concerns of the grapevine nursery industry is a group of fungal trunk pathogens for which there are no effective remedies once planting material is infected. A sizeable but unknown percentage of existing grapevine nursery stock produced under conventional nursery practices is likely to be infected with a broad range of taxonomically unrelated pathogens associated with grapevine trunk diseases (GTDs). These infections can eventually debilitate and kill infected plants after they are planted in the vineyard. Production practices in nurseries provide many opportunities for infection, through poor sanitation practices or introducing infected asymptomatic cuttings from mother vines. Infected plants may initially have no visible symptoms, but they may become apparent after a certain period of time when exposed to field stresses and depending on the level of infection. Detection and identification of these pathogens is challenging, as it requires destructive sampling from different plant parts due to their uneven distribution within the host. These factors represent a challenge for developing a proper clean plant program for GTDs in nurseries. Further research is needed to estimate the impacts of global trade on the dispersal of fungal trunk pathogens in other crops.