Stem-end rot

a dark brown to black, soft, wet rot that begins right at the stem end — the button where the stalk joined the fruit — and spreads out from there like a stain into the sound flesh. Press it and it gives way, mushy and watery, not firm. This almost always shows up as the fruit ripens in the store, the crate or on the way to market, not on the tree.

the dark patch grows outward from the button in a widening ring or tongue. Cut the fruit open and you will see the brown, water-soaked decay reaching in from the stalk end deeper than the skin colour suggests. In warm, damp conditions a grey-to-black fuzzy or sooty fungal growth may appear on the skin at the stem end.

dead twigs, dying branch tips (dieback) and dead bark or wood in the canopy. This is where the fungus lives and breeds — a tree full of dead wood is feeding the rot into your fruit.

anthracnose makes small, round, sunken black spots scattered anywhere over the fruit skin (often with a pinkish ooze), while stem-end rot starts at the button and spreads as one broad rotting front from the stalk end. Also don't confuse it with plain bruising or chilling damage — those come from a knock or from cold, are not centred on the stem end, and do not have the spreading soft-rot edge.

in the late season, from the last weeks before harvest right through picking, storage and transport — that is when the fruit is most at risk, especially in warm, humid weather (about 20–32°C) near harvest and in warm stores or trucks. Warm plus damp plus ripe is exactly when a hidden infection wakes up.

— the infection is hidden while the fruit is green. Instead, scout in two places: the trees (for the source) and your harvested and ripening fruit (for the outcome).

walk a large "W" across the orchard so you cover all corners and the middle, stopping at about 10 trees. At each stop look up into the canopy for dead wood, dieback and dead bark. If you are seeing dead wood in more than about 1 in 5 trees (20%), treat that as your signal to prune and sanitise now — that dead wood is your rot factory.

take a sample of harvested fruit — about 20 fruit — let them ripen, and watch the stem end. Cut a few open at the button. If about 1 in 5 (or more) start to rot from the stem end, take it as a clear warning that your orchard sanitation, harvest handling and cool chain need tightening for the rest of the harvest.

if fruit is sitting warm and un-cooled for hours after picking, or riding in a hot crate or truck, count that as high risk even before you see rot — heat is what lets the latent fungus race.

prune out all dead wood, dead branch tips and dieback and carry it away from the orchard, and keep trees healthy and unstressed. This is the single best lever because it removes where the fungus lives and breeds, lowering the inoculum (the fungus's "seed" — the spores that start new infections) before it ever reaches the fruit.

pick in dry conditions (never off wet, dewy trees), leave a short, clean stalk and do not bruise or tear the button — every wound at the stem end is a door for the rot. Handle fruit gently; rough handling spreads and speeds decay.

get fruit out of the sun and cooled promptly after picking, keep it cool right through storage and transport (the cool chain), and sell and move it quickly. Warm, ripe, slow-moving fruit is what turns a hidden infection into a rotten one.

keep packhouse wash water, crates and packing lines clean — dirty water and dirty crates carry spores from bad fruit to good. Clean, cool handling slows the rot from taking hold in the bin.

where advised, apply a fungicide as pre-harvest field sprays and/or a postharvest dip, or a hot-water dip, strictly per the label, to knock back the latent infections that sanitation and handling alone cannot reach. Safety: cover your skin, eyes, nose and mouth; mix and spray in the cool of the day with the wind at your back; keep it away from food, drinking water, children and bees; respect the pre-harvest interval (the minimum number of days the label says must pass between the last spray and picking, so no chemical remains on the fruit you sell); and wash yourself and your clothes well afterwards. Resistance: do not lean on one chemical — rotate to a different fungicide group between uses so the fungus does not learn to survive it.

if fruit is still rotting from the stem end after you have cleaned up dead wood, tightened harvest and cooling and (where allowed) treated, sort ruthlessly — pull and destroy every rotting fruit so it cannot infect the rest, sell the sound fruit fast and locally rather than risking a long warm journey, and go back to the trees: heavy repeat rot means there is still dead wood and dieback feeding it, so prune harder and keep the trees healthy before the next season. When a batch is too far gone, cut your losses early — bin the rotten fruit, keep it away from the clean fruit, and protect next season's crop rather than chasing this one.