Plant Pathology Science

Introduction: Powdery mildew caused by Podosphaera pannosa is one of the most important diseases of peaches and nectarines worldwide, including Iran. The aim of this research was to investigate the response of peaches and nectarines under cultivation in Iran to the disease. Materials and Methods: Reaction of ten peach cultivars vs. Robin, Early Red, Red Top, Shasta, Amesdn, Velvet, Anjiri, Paeizeh, Dixi Red, and Sun Crest, and ten nectarine cultivars vs. Independence, Stargold, Sangold, Sanking, Giuta, Shabrang Karaj, Vega, Orion, Jiova and Veinberger were evaluated for disease in natural and artificial infection conditions in two experiments in a randomized complete block design with three replications over two years at the Meshgin Shahr Agricultural and Natural Resources Research Station. Results: Analysis of variance of experimental data showed that there was a significant difference between cultivars of each plant at a probability level of 1%. Peach cultivars Anjiri and Red top were very resistant, Velvet, Shasta and Early red ‎were resistant; Amesdn, Dixi red and Robin were moderately resistant; Sun ‎crest was susceptible and Paeizeh was in very susceptible. Weinberger nectarine cultivars were resistant and Independence, Stargold, Sanking, Giuta, Shabrang Karaj, Vega, Orion and Jiova cultivars were semi-resistant and Sangold was very susceptible to disease.  Conclusion: Eighty percent of the studied peach cultivars are very resistant to semi-resistant and 20% sensitive and very sensitive, 90% of the studied nectarine cultivars are resistant to semi-resistant and 10% susceptible to powdery mildew. Findings of this research should be considered in the management of peach and nectarine powdery mildew.

 Introduction: This research was conducted with the aim of determining the reaction of 32 tomato genotypes from the plant gene bank of Iran to the root-knot nematode Meloidogyne javanica, to identify resistant genotypes during two years under greenhouse conditions. Materials and Methods: After purifying the nematode population and planting the seeds of 32 tomato genotypes and reaching the stage of 3-4 leaves, each treatment was inoculated with 6000 eggs and larvae of M. javanica in five replicates, and 60 days after inoculation, vegetative traits and traits related to nematode population were determined in each treatment, and based on gall index (GI) and nematode reproductive factor (Rf), the reaction of genotypes to nematode was determined. Results: Eighteen  genotypes with Rf>1 and GI>2, 23 genotypes with Rf<1 and GI>2, and three genotypes TN-72-938, TN-72-1041 and TN-72-1012 with Rf≤1 and GI≤2, were identified as susceptible, moderately resistant, and resistant to this destructive nematode respectively. Conclusion: These three resistant genotypes can be used in the M. javanica management program.

Bavand, M., Sadravi, M., & Charehgani, H. (2023). Screening of fifteen tomato varieties for resistance to early blight disease. Plant Pathology Science 12(2),1-10. 
 Introduction: Early blight caused by Alternaria species is one of the major tomato diseases worldwide, causing losses of up to 86% of yield. Identifying and cultivating resistant varieties is the best method for disease management. Considering the prevalence and importance of diseases in Iran, this study was conducted to identify resistant cultivars among 15 available varieties. Materials and Methods: In Kohgiluyeh and Boyer-Ahmad province in southwestern Iran, a severely affected tomato field by the disease was visited and samples of the diseased plants were taken. The pathogenic fungus was isolated on potato dextrose agar medium from the diseased tissues of the plant after their surface disinfection and after its purification by the single spore method and its morphological properties were examined and measured. The collected data were compared with the descriptions of Alternaria species and based on that, the pathogen was identified. Seedlings of 15 tomato varieties were inoculated with a conidia suspension at the 4-leaf stage in a completely randomized statistical design and maintained in a growth chamber with a temperature of 28^oC, relative humidity of 90%, and a photoperiod of 16 hours of light and eight hours of darkness. Eighteen days after inoculation, the response of each cultivar to the disease was determined by calculating the percentage of infected leaves as well as the number and size of spots, and the disease index. Results: Alternaria alternata has been identified as the cause of early blight in tomatoes in this region. Varieties 10552, King Stone, Super Chief and Ventero with minimal symptoms were scored as resistant; 4129, 3725, 4224, Retino, Aras, Flat 111 and Super Pooya as semi-resistant and 7806, Early Pooya, 11057 and CH Pooya were known to be susceptible to the disease. Conclusion: Cultivation of resistant or semi-resistant varieties can be recommended for disease control. The occurrence of tomato blight disease caused by A. alternata is reporting here for the first time from the region.