OAKS

are dying.

These trees are on 192 east of Mission canyon. The oak wood beetles select branches that are flooded first.

9/25/02.

Sudden Oak death is killing trees in Marin. This is how I think it can be related to reduced oxygen in water.

The tree draws water devoid of total dissolved oxygen up through the roots. The tree immediately detects that it cannot use the water for photosynthesis without trace amounts of total dissolved oxygen. Having no other way to get rid of water other than transpiration through the photosynthetic process, the tree can store a certain amount in its trunk between the wood and the bark, the cambium layer. The tree then brings up more water attempting to photosynthesize. Obviously it is finding some total dissolved oxygen or it would die immediately. What happens is the trunk becomes flooded. Tan Oaks in the Marin area of Northern California that were diagnosed with sudden oak death in the early phases had flooded trunks. The water stored in the trunk becomes stagnate which is then the perfect medium for the phytophora fungus that then takes over the tree via the cambium layer.

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