Southwest Palms Have Sudden Crown Drop

When the crown of a very large palm tree unexpectedly drops into traffic in Beverly Hills, then people start to take notice. There is a new disease that is attacking Canary island date palms in the southwest and it's particularly dangerous. The fungus responsible for the disease, Thielaviopsis paradoxa, enters through wounds in the trunk causing rot and decay in the interior of the trunk. Usually there are no signs on the exterior of the trunk, however there is still enough sound healthy tissue to keep the crown of leaves looking normal even though there isn't enough structural strength to keep the crown attached for long. When the disease has advanced enough, the weight of the crown is too much and it simply snaps off. This is particularly dangerous because the crown and attached portion of the trunk can easily weigh a ton or more, and when they crash unexpectedly people have been killed. In Beverly Hills alone there are over a thousand canary island date palms. Fortunately, sudden crown drop rarely affects true date palms, the California fan palm or the queen palm. The disease can be controlled through prevention by limiting the use of chainsaws when trimming the ?EUR??,,????'??ball?EUR??,,????'?? just below the leaves. It is easy to knick the trunk or cut too deeply when using a chainsaw, therefore avoid using chainsaws altogether when trimming and pruning and check the trunk frequently for any damage. For more information, contact Donald R. Hodel of the University of California Cooperative Extension in Los Angeles, California at: drhodel@ucdavis.edu.