FUSARIUM WILT
IN CANARY
ISLAND DATE PALMS
Canary Island date palms, Phoenix Canariensis, are
majestic palms that symbolize San Diego and the
Southern Californian life‑style.
Fusarium wilt fungus is always fatal.
However, they are under attack by a fungus known as
fusarium wilt, Fusarium oxysporum f. sp. canariensis.
This fungus is always fatal. It can take a few months
to a few years to kill the tree. There is no cure.
The first sign are dying fronds around mid‑canopy, which is above the level at which they normally die.
The pinnae or leaflets of the frond
die on one side of the rachis or main stem while remaining green on the other as seen in the left and right photos.
The fronds continue to die higher and higher as seen in the left and right photos.
Until the palm eventually dies.
THE CAUSE?
The fungus enters through the root system or, most commonly, through pruning cuts.
What can you do to protect your valuable date palm?
It is theorized that the disease is most likely spread from date palm to date palm by pruning
with infected tools.
What you can do is insist that whoever prunes your trees:
- Remove only dead fronds and not green or yellow fronds. Most customers believe that by taking as many fronds off as possible they greatly extend the time between prunings. This is a false assumption.
- Do not use chainsaws to cut green or yellow fronds if you do choose to remove them.
Use handsaws for these fronds. The debris that gets caught in the teeth can easily be removed and the saw sterilized between date palms.
A chainsaw is impossible to sterilize.
- Prune your date palms during July, August or September. During this time of year the fresh pruning cuts dry the quickest, reducing the window for spore germination.
- Avoid digging in the pneumatode mat (the surface roots around the base of the palm).
Damaging these roots opens them up for infection.
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