Takayuki Momma I can only guess which crop you mind, but there is a case of potato viroid spreading in 1990-2000s due to wide use of meristem culture to get virus-free plant. Selective temperature against viruses favored viroid propagation.

Thanks. I made apical meristem culture with low temperature treatment before. At that time I got some HSVd (Hop stunt viroid)-free hop plants in the 1980s. This technique is spread on Japanese field. But we didn't know Hop latent viroid (HLVd) is damage against hop plant. We have to establish HLVd detection system immediately. In Germany Hop meeting for virus and viroid will be held on this April. I that meeting they discuss about this problem, maybe. Alex Ignatov

Takayuki Momma I see some similarities between latent viroid infection and latent virus infections. Latent infections are usually slower than more aggressive strains or combinations of viruses. To detect latent infections, we must test plants at a later stage, sometimes 2-4 weeks after usual control point, and the entire process of selecting virus-free plants needs to be modified. This is also true for selecting viroid-free plants.