Influence of water stress on susceptibility of red oak (Quercus rubra) to Phytophthora cinnamomi

Influence of water status of oak trees (Quercus rubra) on the development of Phytophthora cinnamomi lesions was studied. On agar media or excised inner bark, growth of P. cinnumomi was reduced by low water potentials. In contrast, on voung saplings or mature oak trees the development of P. cinnamomi lesions was not affected during a period of water stress. But after the end of the water stress treatment, susceptibility of the young saplings to P. cinnamoni increased.