The effects of salinity on Phytophthora ramorum viability and infectivity.

Author , , ,
Date 2011.
Publication Phytopathology 101:S146.
Key Words
AbstractPhytophthora ramorum, a threat to Eastern U.S. forests, has been found in waterways outside the boundaries of infested ornamental nurseries. Very little is known about what factors are conducive to its survival and sporulation in water. Water collected from various sources with different salinity was used to better understand what effect salinity has on the life cycle of P. ramorum and infection of tissue. Water samples were collected from natural bodies of water with conductivities of 5.6, 30.5, 32.3, and 35.3 in May 2010. The water samples were added to cups containing P. ramorum-infested sand (1,000 chlamydospores/cc). Rhododendron leaf disks were placed on the water surface for 1 week at 20 C and then plated on Phytophthora-selective medium (PARPH+V8). Very few leaf disks (≤ 3%) were infected at the three highest conductivity levels while 100% infection occurred at 5.6 mS. Similarly, Rhododendron leaf disks were placed on the surface of different salt solutions added to P. ramorum–infested sand at two chlamydospore levels (100 and 1,000/cc) for 1 week and plated on PARPH+V8. The leaf disks were exposed to the conductivity levels of 10.3, 26.5, 36.0, 57.2, and 67.9 mS. The disk infection rates at 100 spores/cc were 61.1, 23.1, 3.3, 0, and 0%, respectively, while infection rates at 1,000 spores/cc were 100, 70.0, 55.6, 2.2, and 0%, respectively. This research helps to better understand the survival and factors affecting infectivity of P. ramorum.
Full Citation Preuett, J.A.; Collins, D.J.; Luster, D.G.; and Widmer, T.L. 2011. The effects of salinity on Phytophthora ramorum viability and infectivity. Phytopathology 101:S146.