Peach latent mosaic viroid occurs on stone fruits other than peach and can be transmitted by razor blades
As stated in EPPO Reporting Service 96/175, peach latent mosaic viroid (the A1 entry is ‘American peach mosaic’) is more widely distributed than previously thought. Further studies have been carried out and have confirmed that peach latent mosaic viroid is indeed distinct from the causal agent of American peach mosaic disease observed in south western USA and Mexico. The later is still uncharacterized, and so far thought to be related to cherry mottle leaf closterovirus. Until now, peach was considered as the only host for peach latent mosaic viroid, as it was not possible to detect the disease on other stone fruit species by graft testing on several indicator plants followed by re-testing on peach GF-305. But by using molecular techniques (PCR), it was possible to detect peach latent mosaic viroid in cherry, plum and apricot plants from countries in Europe (Italy – see also EPPO RS 97/093, France, Romania, former Yugoslavia) and Asia (Nepal). The nucleotide sequence of a sweet cherry isolate has been studied. It was found that this isolate is 91 to 92 % homologous with peach latent mosaic isolates (French and Italian) from peach. Concerning apricot and plum isolates, further studies are needed on their relationships with peach isolates. The authors noted that peach can be considered as the major host of peach latent mosaic viroid, but that plum, apricot and cherry are also natural hosts, although the pathogen is rare on these plants.
In addition, studies were carried out on the mechanical transmissibility of peach latent mosaic viroid. Experiments demonstrated that the viroid could readily be transmitted with contaminated razor blades. This observation suggests that peach latent mosaic viroid may be transmitted in orchards from infected to healthy trees by pruning equipment.
Sources
Hadidi, A.; Giunchedi, L.; Shamloul, A.M.; Poggi-Pollini, C.. Amer, M.A. (1997) Occurrence of peach latent mosaic viroid in stone fruits and its transmission with contaminated blades.
Plant Disease, 81(2), 154-158.