Fruitlet core rot

slice a ripe pineapple down the middle and look at the eyes near the core. Affected fruitlets show a firm brown-to-black rot at their centre, about the size of a small bean, while the flesh around them still looks yellow and healthy. Usually only some eyes in a fruit are rotten, not all of them.

the skin normally looks completely normal. Sometimes an affected eye is slightly sunken or a little darker than its neighbours — but you often cannot tell a rotten fruit from a good one until you open it.

black-heart makes a water-soaked, translucent brown patch that starts at the core and spreads outward through the whole fruit, and it comes from fruit getting too cold after harvest — not from the flower. Core rot stays as separate firm brown spots in single eyes, scattered, with good flesh in between.

marbling (a bacterial problem) turns the lower flesh hard, woody and reddish-brown in streaks. Core rot is a soft-to-firm rot centred on the eye's core, not woody streaks through the flesh.

from flowering right through to harvest — this is your fruit-filling and ripening window (the crop's mid- and late-season stages), when the rot that entered at bloom is developing inside. Pay special attention to any block where the flowers opened during wet, humid, or rainy weather, because that is when the fungus gets in.

Walk a large "W" across the block so you cover all four corners and the middle, not just the row by the path.

from different points along your "W" (pick fruit that are near maturity), and slice each one down the middle to look at the eyes around the core.

if you find brown rotten fruitlet cores in even 1 of the 10 fruit you cut, treat that whole block as a known problem block — the disease is present and will hit again. Mark it, and put your prevention effort into that block's next flowering.

(was it wet? humid?) for each block, plus how many flowers were still open and moist. Wet flowering + past rot = the blocks to protect first.

the fungus is ferried into open flowers by mites and small flower-visiting insects (these are the "vectors" — the little carriers that move the disease). Keep them down: remove weedy flowering plants around the block that feed them, and keep the field clean, so fewer of them reach your open pineapple flowers.

in a high-value block that keeps getting hit, an acaricide (a mite-killing spray) applied around flowering knocks down the mites that carry the fungus into the flowers. Safety every time: cover your skin, eyes, nose and mouth; spray in the cool of morning or evening with the wind behind you so it blows away from your face; keep it off food, drinking water, children and bees; wash yourself and your clothes afterwards; and respect the pre-harvest interval — the number of days you must wait between the last spray and picking the fruit, printed on the label — so no chemical is left on fruit you sell. To stop the mites becoming immune, rotate to a different chemical group each time rather than using the same one over and over (that build-up of immunity is called resistance).

once a fruit is rotting inside, you cannot cure it — no spray reaches the core. If a block shows rot at harvest, cut your losses on that fruit: sell or process the affected fruit quickly rather than storing it, keep clearly-rotten fruit out of your good sales lots so a buyer's cut doesn't reject the whole batch, and remove and destroy rotten fruit so it doesn't seed next season. Then put everything into protecting that block's next flowering — dry-weather forcing, a tougher variety, clean fields, and mite control — because that is the only flowering you can still save.