Divisi
Avocado sunblotch viroid
Avocado sunblotch viroid · Viral
Photo: Francesco Di Serio, Shi-Fang Li, Jaroslav Matoušek, Robert A. Owens, Vicente Pallás, John W. Randles, Teruo Sano, Jacobus Th. J. Verhoeven, Georgios Vidalakis, Ricardo Flores · CC BY-SA 4.0
Avocado sunblotch is caused by a viroid — a tiny piece of infectious RNA, even smaller than a virus — that lives inside every part of an avocado tree for the rest of its life. It does not blow in on the wind or come from insects. You carry it into your orchard yourself: on grafting and pruning knives, in budwood or cuttings taken from a sick tree, through roots that touch and join underground, and in seed from an infected tree. The cruel part is that many infected trees look perfectly healthy (they are called symptomless carriers) yet still pass it on and still give a poor crop.
148LENIN · CC BY-SA 4.0
Why it matters
Once a tree has sunblotch it has it for good — there is no spray and no cure, and the tree will quietly give you a smaller, scarred, unsellable crop for the rest of its life. A run of infected and hidden-carrier trees can cost you up to 30% of your harvest. It is so hard to beat because it spreads invisibly — on your own knife, through touching roots, and in trees that look green and healthy but are secretly infected — so by the time you see the streaks, it has often already moved to other trees.
When to act
Any tree showing sunblotch symptoms or any confirmed positive symptomless carrier is removed; there is no in-tree cure.
This guidance is general, compiled from published agronomic references including FAO and CABI. Thresholds and timing shift with your crop, your variety and the season.
In much of the region a spray is simply called mushonga — medicine. But a chemical group you cannot name is one you cannot rotate, and a product you did not write down has no pre-harvest interval you can observe. Mushonga, and other farming words →
The full avocado sunblotch viroid field guide
- Identify it
- Scout for it
- Control it
14 field-guide sections in the app
The full guide to avocado sunblotch viroid — every symptom to check, how and when to walk your field looking for it, and the controls that actually work, ranked. Built into your crop plan, so you are told to look before it costs you a harvest.
Crops it affects
Frequently asked questions
How do I identify avocado sunblotch viroid?
The first thing you notice: bright yellow, cream or pink streaks running along young green stems and along the fruit — long marks that follow the length of the shoot, not round spots. The streaks often look slightly sunken, like a shallow scratch pressed into the skin.
When should I take action against avocado sunblotch viroid?
Any tree showing sunblotch symptoms or any confirmed positive symptomless carrier is removed; there is no in-tree cure.
How do I control avocado sunblotch viroid?
Prevent first — this is your strongest tool (it works about 9 times in 10): only ever plant or graft from viroid-indexed, certified-clean budwood and rootstock. "Indexed" means the mother tree was laboratory-tested and proven free of the viroid. Never take budwood, cuttings or seed from a tree that has not been tested — that one shortcut is how most orchards get infected.
Which crops does avocado sunblotch viroid affect?
Among the crops covered here: Avocado.
Catch it before it costs you a harvest
Divisi builds scouting into your crop plan — it tells you when to walk your field, what to look for at that stage, and what to do when you find it. Free for farmers, works offline.
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