Nut symptoms

Symptom

Possible cause

Yellow-green mould spores on fleshy part of the nut (© Franz E. Kohler, Kohler Collection)

Healthy nuts (left) vs. diseased rounded nuts with reduced husks (right) (© Dagmar Hanold and John Randles, Waite Agricultural Research Institute)

Scarring and discolouration to coconut from insect feeding and honeydew excretions (© Scot Nelson, Flickr)

Cocoa mealybug

Pineapple mealybug

Striped mealybug

Coconut mealybug

Deep brown cracks appearing on a nut from necrotic lesions made by a sap feeding bug (lower left corner) (© Bernhard Loehr, ICIPE)

Coconut bug

Additional symptoms of coconut bug include: 

• Brown spots (necrotic lesions) that appear on the young nuts.
• Gum oozing out of the lesions.
• Young nuts fall early.
• Stunted and abnormal growth of the nuts.
• Feeding damage on other succulent parts of the fronds.
• Wilt and death of plant tissues.

Young nut showing necrotic lesions internally made by a sap feeding insect (© Pieter Schalk Schoeman, Agricultural Research Council)

Coconut bug

Additional symptoms of coconut bug include: 

• Brown spots (necrotic lesions) that appear on the young nuts.
• Long crack-like lesions.
• Gum oozing out of the lesions.
• Young nuts fall early.
• Stunted and abnormal growth of the nuts.
• Feeding damage on other succulent parts of the fronds.
• Wilt and death of plant tissues.

Gum oozing out of from lesions made on a young nut (gummosis) by a sap feeding insect (© Bernhard Loehr, ICIPE)

Coconut bug

Additional symptoms of coconut bug include: 

• Brown spots (necrotic lesions) that appear on the young nuts.
• Long crack-like lesions.
• Young nuts fall early.
• Stunted and abnormal growth of the nuts.
• Feeding damage on other succulent parts of the fronds.
• Wilt and death of plant tissues.

Initial symptoms on a young nut showing pale yellow triangular areas underneath the perianth (© James V. DeFilippis, University of Florida)

Coconut mite

Damage to a young nut, concentrated to the left side under the perianth causing uneven growth of the nut (© Forrest W. Howard, University of Florida)

Coconut mite

Enlarged brown area that looks cork-like with long narrow splitting and cracks. Appears after yellowing of these areas (Scot Nelson, Flickr)

Coconut mite

Young coconuts and their inflorescences showing a condensed mass of scaly insects. A closer look may show different sized, yellow to brown scale insects (© Bernhard Loehr, ICIPE, Bugwood.org)

Coconut scale

Nut halves showing brown staining at the site of boring by an insect larvae and on the kernel (L) and gum-like substance oozing out of the bored hole with larvae feeding (R) (© Rajesh K. Patel, AICRP (PALMS))

Coconut spike moth

Nuts fallen before maturity with brown-black rot at calyx-end (© Nigel A. Harrison, University of Florida)

Lethal yellowing

Additional symptoms of lethal yellowing include: 

• Blackening and rotting of the inflorescences (flower clusters).
• Fronds die and hang down.
• Death of the emerging spear leaf.
• Death of the growing point of the palm occurs next.
• The crown falls, leaving a dead trunk only, sticking up like a telegraph pole.

Large holes (around 5cm in diameter) gnawed in to fallen nuts. Usually young green nuts (© TNAU)

Rats

Healthy nuts (left) vs. diseased thin and small nuts with scarring (right) (© Dagmar Hanold and John Randles, Waite Agricultural Research Institute)

Healthy nuts (left) vs. diseased nuts showing no central kernel (right) (© Dagmar Hanold and John Randles, Waite Agricultural Research Institute)