Oak Woodlands

The Problem

The Word "Acorn"

Oak Flowers

Leaf Galls


Natural Planting

    Annual Weeds

Life in Mature Trees
    "Spanish Moss"
     Leaping Lizards
     Diseases, Decline
     Sudden Oak Death

Key to Oak Species

     Planting Trees
     Climate Change

Diseases, Insects, Fungus

   Without a doubt, the best source of information on agents of death to California oaks is found in the "CODA" or California Oak Disease and Arthropod Database. This is a web-searchable database including information from on over780 arthropods, 200 disease organisms and over 200 saphrophytic fungi. You can search by symptoms, descriptions, etc. Go here: CODA Database

Even infected trees are valuable

     Jepson, the botanist associated with the large, detailed reference book, "The Flora of Californa" once noted that it takes about 100 years for an oak to grow to a tree and another 200 years for everyhing growing in the oak to kill it. Virtually every oak has a long list of pathogens, parasites, herbivores, epiphytes, and even the occasional tree house. Even hollow trees may hang on for decades. As long as they stand on their own, they provide habitat for many other plants and animals.

    As the tree ages, many organisms begin to take their toll. If you live among the oaks, you soon realize that the winter rains and fungal growth weakens the branches. Every old ok we have seen fall has been an empty shell. Water applied within the rooting area of an old oak tree in sufficient quantities to keep turf, other groundcovers or moisture-intensive plants in good condition means almost certain death for most oaks. Armillaria mellea or "oak rot fungus" is an organism that thrives under high-moisture conditions, is highly pathogenic, and under such conditions, frequently fatal to oaks.

Oak with fungus growing in heart wood. Note the hollowed section in the center. Above this, the oak was essentially a hollow tube.


Bats, grounds squirrels, woodpeckers. skunks, foxes and many other animals live in these hollowed logs, soon to be felled by the humble fungus.We have had a very hard time aging the majestic fallen oaks because most are hollow all the way to the ground. However, some have are entire at the ground level.





Branch on this Coast Live Oak failed near Carmel Valley Village, Monterey County. The hollow of the upper branch was continuous with the hollow from an old branch, with entrance facing the camera, lower on the tree.



When big branches fall, it is often seen that they fail where the tree is hollow.



Information held about the climate of the last 300 years may be hidden in those stump; as reflected by the pattern of wide growth rings (wet year) and narrow growth rings (dry years). Unless the tree grew where it was always wet, this pattern can give us insights into past climates.




Close up of valley oak stump from tree above. Annual growth rings appear as light bands, the radial lines are vascular bundles. Annual growth rings occur as rings around the tree, with a new ring each year. If it is a wet year, the tree grows faster and the ring is wider. On dry years, the rings can be very narrow.