Investigation of Some Effective Factors on Production and Pathogenicity of Zoospores of Phytophthora capsici and P.nicotianae on Tomato Fruit

Some species of Phytophthora genuse cause crown and root rot, and damping off of tomato seedlings. Fruits that contact with soil containing pathogen are affected by a type of decay called buckeye rot of tomato. In this research Pathogens were isolated from soil, tomato root and crown in North Khorasan province and identified as Phytophthora capsici and P.nicotianae . Pathogenicity of both species were demonstrated on tomato seedlings.The production Zoospores was investigated under different light and temperature conditions. The results showed that there was a significant differences between species in reaction to temperature condition. Temperature also had significant effect on the release of zoospore in both species. The highest release of zoospores occured in one of the P.capsici isolates at 20°C under dark conditions.In the case of P.nicotianae at 25°C and light conditions the highest zoospore were released. The largest wound length occurred in isolate Pc2 of P.capsici . It reached to 50 mm at 25°C and dark condition after 5 days. In the case of P.nicotianae the highest pathogenicity of zoospores occured at 27°C under light condition.