Phytophthora kernoviae oospore maturity, germination, and infection.

Limited information is known on the basic biology of the recently described Phytophthora kernoviae that produces homothallic oospores. In this study, different P. kernoviae isolates were used to investigate oospore maturity, germination, and infection. All isolates produced oospores in V8 broth at 20°C in the dark by 6d. Oospores also formed at 10 and 15°C, but did not form at 25 and 28°C. Continuous light inhibited oospore production of some isolates but had no negative effect on others. Maturation time of the oospores, as noted by germination and staining with tetrazolium bromide, was not much different among the isolates between 2 and 14 weeks. Oospore germination was optimal at 18 and 20°C, and did not occur at 5, 25, and 30°C. Oospore germination under continuous light was higher than in the dark, but individual isolates showed variable results. Rhododendron leaf disks inoculated with oospores and maintained in the dark at 20°C were necrotic after 1 week, while those kept under continuous light did not develop necrosis. The percentage of leaf disks infected with P. kernoviae was lower in the leaves exposed to continuous light (40%) compared to those kept in the dark (100%).

Pistachio gummosis disease caused by Phytophthora species and its control management with soil solarisation method in Iran.

Pistachio (Pistacia vera L.) is the most important commercial product in Iran and root rot or crown rot (Gummosis) is the most serious diseases of this crop. During 2005-2007 Infected trees of Pistachio orchards were visited and plant samples plus soils around the infected trees collected from Kerman province in Iran. Samples were transferred to laboratory and cultured on common medium and using citrus leaves pieces as baits on water-saturated soils. Different Phytophthora species were isolated and studied to be identified. Three Phytophthora species including P. megasperma, P. drechsleri and P. citrophthora were the principal cause of pistachio gummosis and root rot in Iran. However, Phytophthora pistaciae as new species was introduced as aggressive species to different Pistachio cultivars. Since chemical control was not property managed the disease, soil disinfestations by soil solarisation method was carried in Kenrman as the nearly warmer climate in studied areas to manage the pathogen. Application of this method reduced population density of the pathogen from 1300 to 200 CFU -g/soil after 6 weeks. This method was effective, non negative side and economic which can be used in all agricultural areas.