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 developm ent of Phytophthora cinnamomi lesions was studied. On agar media or ex cised inner bark, growth of P. cinnamomi was reduced by low water pote ntials. In contrast, on young saplings or mature oak trees the develop ment of P. cinnamomi lesions was not affected during a period of water stress. But after the end of the water stress treatment, susceptibili ty of the young saplings to P. cinnamoni increased.