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Sunburn damages both leaves and fruit on pineapple when high radiation combines with drought, low humidity, or reduced canopy cover. Fruit sunburn is the yield-critical form: it downgrades fresh-market fruit and creates entry points for rots. Sunburn is not a disease but is often mistaken for one. Regional priority: High on exposed sites, thin canopies, ratoon blocks (uneven cover), and any block with fruit exposed to direct afternoon sun.

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When pineapple is most vulnerable

Most damaging during fruit development and ripening (months 14 to 22), especially the west-facing rows and outer rows. Also affects immature plants during establishment on BRIS or open sites.

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How sunburn shows in satellite data

  • Not directly detectable at Sentinel scale in most cases; damage is on individual fruit shoulders.
  • On drone or very-high-resolution imagery, bleached leaves show as brighter reflectance on west-facing rows.
  • Indirect indicator: sustained high solar radiation + low NDWI over the block during fruit development is a sunburn risk signal.
  • Confirm on the ground.

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Field symptoms

  • Bleached, papery patches on leaves exposed to the sun (west or south side)
  • Sun-scalded fruit shoulders - the upper, sun-facing side of the fruit turns pale, then brown, then leathery
  • Cracked fruit skin on the scalded area, often followed by black rot
  • Corky, tough flesh below the scalded skin
  • Damage concentrated on west-facing rows and outer rows

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Reduce the damage by

  • Cover fruit with dried leaves tied over the fruit shoulders (traditional method, effective and cheap).
  • Use paper or fabric fruit covers on export-quality MD2 and Josapine.
  • Plant rows north-south where possible; east-west rows expose fruit to direct afternoon sun.
  • Maintain full canopy - avoid excessive N late in the cycle that causes older leaves to lean out and expose fruit.
  • Kaolin-clay spray on fruit shoulders reduces radiation load on high-value blocks.
  • Time forcing so fruit development avoids the hottest, driest weeks of the year where possible.
  • Irrigate during heat spells - well-watered plants transpire and cool the fruit; dry plants overheat.

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Set an alert for early warning

Turn the diagnosis into a trigger. Sunburn risk correlates with radiation and evaporation, not NDVI, so use weather and canopy-cover signals.
Recommended settings for sunburn on pineapple:
  • Weather alert - 3 or more consecutive days with maximum air temperature above 34 C and solar radiation above 25 MJ/m2/day during fruit development.
  • Canopy-cover alert - trigger on blocks with NDVI below the mid-fruit-development baseline (indicates exposed fruit).
  • Fruit-cover reminder - schedule a walk-through 2 weeks after forcing to install fruit covers on all west-facing rows.