Tree Blog

((Q. macrocarpa x robur) x lobata) x lobata | Central Valley

This tree, being grown in a nursery in the Central Valley of California, likely started life as one of the acorns pictured on the previous page. If hybrids of a similar oak type are to be grown in coastal California, or anywhere else that powdery mildew occurs, it is wise to grow the seedlings in a location where powdery mildew occurs, and, as the seedlings grow, any that show symptoms of powdery mildew, or other disfiguring disease, are best culled, and destroyed. Powdery mildew resistance is highly variable even amongst closely related oaks - some are immune, while others are fatally susceptible, with every variation in between. Climate change may bring powdery mildew to new locations, so a disciplined application of culling is likely to give excellent long term results, while weak culling will result in tragically poor landscape outcomes. This is a key reason that unusual oaks are so rare in coastal California - uninformed experimentation has led to many failures, and a feeling that the endeavor is hopeless. It is not - foresight and discipline are required.

 

Dave Muffly