University of Hawaii

Abnormal loss of small to nearly mature nuts has been a common early sign of this disease. Infected fruits have dark, mottled spots and rots. Irregular expansion of brown infected areas frequently creates circular green patches or islands of green tissue surrounded by diseased areas. Water soaking is also common on large immature fruits and appears as dark green, oily tissue bordering diseased areas. Very young diseased fruits less than 7.5 cm (3″) long are generally brown without mot­tling. Internally, the infected husk of older fruits is reddish to red-brown. The infect­ed meat, or endosperm, is white, cream colored, or slightly brown. The pathogen may penetrate mature nuts by growing through the germina­tion pore at the stem end of the nut.

The first symptoms on young or mature trees are wilting, discoloration, and death of the youngest leaf. Unfurled spear leaves may also die early in the course of this disease. Dead fronds are bent abnormally but remain attached to the trunk for a few weeks, drooping onto or between the older green leaves. In the ensuing months, more leaves die and fall, leaving a few lower fronds. Roots and lower trunk tissue remain healthy and functional for many months and continue to supply the lower leaves with nutrients and moisture. Eventually all of the fronds drop, producing leafless trunks.

Less frequently, older leaves die first, result­ing in trees with only a few young, upright fronds. Because young leaves are vertically oriented, infected plants appear rigid or stiff.

By the time leaf death is observed, internal heart rot is already at an advanced stage. These diseased trees have large rotted areas that involve most of the terminal bud. Killing of the single growing tip ultimately causes the death of the palm.

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