Avocado sunblotch viroid

Avocado sunblotch viroid is the smallest known plant-infecting pathogen and causes a disease of avocado trees that reduces yield and fruit quality, sometimes by thirty percent or more. It spreads through pollen and through contaminated seeds or budwood, and many infected trees show no visible symptoms beyond reduced productivity while still acting as sources of further spread; where symptoms do appear they include yellowish streaks on fruit, discolored areas and bark damage on branches. Viroid concentration varies enormously between branches of the same tree and between different trees, which complicates detection and management, and diagnosis relies on PCR testing. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/