Avocado sunblotch viroid

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.

affected shoots push out narrow, strap-like, twisted leaves — much thinner and more crooked than the broad, flat healthy leaves around them — sometimes with pale bleached blotches. That deformed new growth keeps coming back on the same branch.

infected fruit is cracked, scarred and blotchy, with the same yellow-cream-pink sunken streaks. It is misshapen and downgraded — buyers reject it.

some carrier trees show no streaks at all, only rectangular cracking of the bark on the trunk or limbs, and generally weak, stunted growth with a poor crop for no obvious reason.

sunburn/scald bleaches the side of fruit and leaves facing the sun (sunblotch marks appear anywhere, in streaks). Iron shortage yellows between the leaf veins while the leaf keeps its normal broad shape — that is a good way to rule it out. Zinc shortage is trickier: it also makes leaves small and narrow (called 'little-leaf'), so leaf shape alone will fool you — but zinc-short leaves stay an even pale-green with no coloured streaks, whereas sunblotch always adds yellow-cream-pink lengthwise streaks on the shoot and fruit. Herbicide drift and wind-rub scar fruit but do not make the long coloured streaks or the twisted strap leaves. Sunblotch is the one that gives coloured lengthwise streaks + narrow twisted leaves on the same shoot.

walk your orchard whenever new growth (flush), sizing fruit and mature fruit are on the tree — that is the tree's development, mid-season and late-season stages, when the streaks show most clearly. Look at least once each of these times every year, and always before you cut budwood or take cuttings.

cross the block in a big "W" so you pass through all four corners and the middle, not just the row by the path. Stop and inspect around 10 trees spread across the W.

the new shoots for yellow-cream-pink streaks, the leaves for the narrow twisted strap shape, the fruit for coloured sunken streaks and scarring, and the trunk and lower sprouts for rectangular bark cracking. Bend down and check low water-sprouts too — signs often show there first.

Unlike a caterpillar you tolerate up to a threshold, there is no safe number here. Find even a single tree with these signs → mark it and act now. Any tree you suspect of being a mother (budwood) tree must be indexed (laboratory-tested for the viroid) before you ever cut wood from it — a healthy-looking carrier will infect every tree you graft from it.

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.

the viroid rides on blades. Disinfect every knife, secateur and pruning saw with household bleach (sodium hypochlorite), about 1 part bleach to 9 parts water, between every single tree. Prune your known-healthy trees first and any suspect trees last, so you never carry it from sick to clean. Safety with bleach: wear gloves, keep it off your skin, eyes and nose, mix and work in a well-aired spot, keep it away from children, and wash your hands and tools with clean water after.

source your young trees only from a clean nursery that runs a tested mother-block scheme (a set of proven-clean parent trees kept only for propagation). Ask to see their indexing records before you buy — it is the same principle as planting indexed budwood, just moved back to where your trees are raised.

no chemical, no spray and no medicine can clear a viroid from a tree, whatever a seller may claim — do not waste money on one. The only real action is to rogue the tree: cut it right out and destroy it (burn it or bury it well away from the orchard). Take out the stump and as many roots as you can, because roots of neighbouring avocados grow together underground (root grafts) and pass the viroid tree-to-tree — a live infected stump keeps infecting its neighbours.

Remove every confirmed and symptomatic tree plus any neighbour sharing its roots; stop taking any budwood from your own orchard until the source tree is indexed clean; and re-plant the gaps only with certified-clean, indexed stock. When a tree is a proven carrier there is nothing to save — replacing it early protects the up-to-30% of your crop the whole orchard would otherwise keep losing.