Plant Doctor Archive

Brown palm

CAN you tell me what has happened to my Washingtonia palm? Over the summer it has turned from lush to deformed. I have several other healthy ones nearby. Will the same thing happen to them? Will it ever recover or should I remove it?

FROM the photo it looks like your palm may be suffering from root rot. Try gently rocking one of your healthy palms a little to see how secure it is in the soil then do the same to the sick one. If the sick one rocks easily and seems loose in the ground, then root rot is probably to blame and there's not a lot you can realistically do to save it.

As it's obviously a young plant, it could be that damage to the root system at planting time, or excessive moisture around the roots for some time after planting, is the cause. The best time to plant palms to avoid root rot problems is in spring and summer when the soil is warm, rather than in winter.

Alternatively, if the root system does feel secure, it could be that the crown of the plant is infested with earwigs. Earwigs damage the new leaves before they emerge from the trunk so when they do come out they can look similar to those in your photo. So have a look down into the centre of the growing point and check for earwigs. Or, just to make sure, you could drench the centre of the palm with a solution of an insecticide such as Target.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.