Quercus engelmanii | Stanford
This is another young Engelman Oak at Stanford University, this time grown from a seedling, with the acorn originally collect at the Shields Oak Grove in Davis. Tree shelters are a woefully misunderstood and under-utilized aid to tree establishment in coastal California. In climates that receive summer rainfall, leaf diseases (coupled with large leaf sizes) can be a major nuisances in using tree shelters. But in the arid western US, the smaller, drought-adapted leaves, which also typically have a waxy cuticle to retard rates of evapotranspiration, together make in-tube leaf diseases rare. Tree shelters should be left on until the trunk is obviously self-supporting. Often users remove the tubes prematurely, and then struggle to keep the trunks straight - there is no reason (beside the always subjective aesthetic question) to take away the tube. And, if there are trunk-gnawing tree predators (like voles) around, keeping the tubes in place may prevent heartbreaking tree loss, or having a start-over situation where the upper portion of the tree dies, and the roots vigorously resprout from the roots, thus losing years of top tree growth.