Tree Blog

Quercus agrifolia vs. Quercus virginiana | Santa Clara County

Here we see the tale of two very different Live Oaks, from California, the Coast Live Oak (Quercus agrifolia), and from the southern US, the Southern Live Oak (Quercus virginiana). They are growing in the deep alluvial soils of the southern reaches of Santa Clara County. There is obviously lawn watering beneath both, though the lawn is worn and outcompeted close to the trunk. The Coast Live Oak has grown luxuriantly and quickly, as shown by the "fuzziness" of the canopy. The Southern Live Oak has also grown rapidly for the species, but at a more measured pace. Lawn can initiate root diseases which can kill Coast Live Oak, while Southern Live Oak thrives with the additional summer water. The pace and extent with which Coast Live Oak is damaged by lawn-associated root diseases appears to correlate well with soil drainage, and intensity of summer irrigation. 

Dave Muffly