**3.6** *Citrus bark cracking viroid (CBCV) or Citrus viroid IV*

This viroid belongs to *Cocadviroid* genus, *Pospiviroidae* family. This genus has 246–301 nucleotides and its secondary structure is rod-like or quasi-rod-like with five domains the same as other genera. These viroids induce symptoms in citrus plants but recently this viroid causes severe symptoms on the hop. Although dues to this viroid, Etrog citron shows leaf drooping and necrosis of the leaf midribs, it does not have a minus effect on growth and yield in citrus. If CBCV and HSVd infected one tree, the symptom is severe and you will have observed yield reduction. These viroids have a synergistic effect [18, 51].
