Sudden oak death, caused by Phytophthora ramorum, is rapidly changing the composition and structure of forests in California and other parts of the world. Host resistance to infection varies widely within and among species, but little is known about the complex physiological and biochemical interactions contributing to resistance. However, it is known that P. ramorum must capture sterols from its host tissues by secreting small proteins, called elicitins, in order to grow and sporulate. A recent study suggests that tannins in host tissues could potentially interfere with the elicitin mediated acquisition of sterols and thus impact the growth, sporulation, and virulence of P. ramorum. Tree improvement and breeding programs can produce trees with increased resistance, but the development time can be accelerated, and quality of the new stock maximized when, knowledge of traits contributing to resistance are known.