Sepideh Hoseinkhaniha - University of Guilan, Rasht, Iran
Seyed Akbar Khodaparast - University of Guilan, Rasht, Iran
Mohamad Mahdi Zarabi - Imam khomeini international university, Qazvin, Iran
Seyed Reza Razaz Hashemi - Qazvin Agriculture and Natural Resources Research Center, Qazvin, Iran

Powdery mildew is one of the most important disease concerns of tomato production in different regions of the world, which is caused by different species of Erysiphales. The most important causal agents of which are Leveillula taurica and Oidium neolycopersici. In the present study tomato farms in Qazvin province were surveyed and tomato leaves with powdery mildew symptoms were collected. After morphological studies in laboratory and using reliable resources, the causal agent of tomato powdery mildew was identified as Leveillula taurica. The host range was determined by inoculation of Leveillula taurica from tomato on nine species of plants belonging to four different plant families. All cultivars of tomato, eggplant, pepper and cucumber used in this study, showed disease symptoms on their leaf surfaces. Other plant species including potato, alfalfa, sunflower, clover and sainfoin did not get infected by the pathogen. The nucleotide divergence for the rDNA internal transcribed spacers (ITS) region between tomato mildew and ۲۱ other Leveillula taurica isolates ranged from ۰.۰۰ to ۰.۰۳۱ %. The sequence of ITS region of Leveillula taurica from tomato was identical to that of eight isolates from different plant species.

Oidium, Leveillula taurica, Erysiphales, rDNA