Threats to palm trees

South American palm weevil 1. Palm weevil burrows into the leaf base and lays its eggs. 2. Once hatched, the larvae move into the trunk of the tree. 3. They begin to eat the tree’s core, causing it to rot. 4. If the tree is not removed, its crown will eventually fall.

Sudden crown drop decays the core of a trunk, weakening the structure of the palm. Eventually, the top of the palm topples to the ground. The disease is spread through unsterilized chainsaws, mulch made of infected palms and improper irrigation.

Red ring is visible in the cross-section of an attacked palm’s trunk. The red ring nematode, or worm, travels with the South American palm weevil. It has not reached California, though researchers said a pathogen like this usually follows closely behind its host.

The polyphagous shot hole borer carves tunnels in palm trunks to lay its eggs. Ten types of palms are susceptible to the beetle. Scientists first detected the East Asian beetle in Los Angeles County in 2012. By 2017, it spread to five other counties in Southern California.

Pink rot stunts the growth of new leaves and may eventually cause the trunk of the tree to rot. The fungus grows pinkish spore masses. Palms that are planted too deeply, overwatered or already battling other diseases and infestations are most susceptible to pink rot. Fusarium fungus 1. Fungus in the soil enters the palm tree through its roots. 2. Colonized fungus clogs vessels the tree uses to transport nutrients. 3. Lower leaves die first, followed by the middle and newest leaves.