Plant Pathology Science

Introduction: Canola is one of the most important oilseeds in the world. Fusarium species can causes of canola root and crown rot. Material and Methods: In order to identify Fusarium species associated with rapeseed, some samples of the roots and crown of infected and suspicious plants were taken from rapeseed fields in the counties of Lorestan Province during the 2018 growing season. The samples were transferred to the laboratory and pathogenic fungi isolated and purified using specific and public media and then identified with valid keys. Results: A total of 88 isolates were obtained from the collected samples, which due to the morphological characteristics as F. acuminatum, F. culmorum, F. diversisporum, F. oxysporum, F. sambucinum, and F. solani. F. culmorum with 21 isolates (23.86%) and F. solani with 7 isolates (7.95%) had the highest and lowest frequency percentage, respectively. Conclusion: Canola is reported for the first time as a new host for F. diversisporum and F. sambucinum in Iran.

Introduction: Poaceous plants such as corn, wheat, barley, sorghum, oats and millet are an important part of agricultural ecosystems. Smuts are one of the most important fungal diseases of these plants, which often cause economic damage and the destruction of part or all of their yields. Materials and Methods: Poaceous smut infected plants in farms and pastures of Markazi and Lorestan provinces were sampled. Morphological characteristics of these fungi and their germination type of teliospores were studied with bright field and fluorescent microscopes and identified using valid keys. The phylogenetic relationship of these fungi with other smuts was also investigated based on ITS-rDNA region sequencing. Results: According to the type of host, morphological characteristics and mode of teliospores germination 12 species vs. U. maydis, U. hordei, U. turcomanica, U. avenae, U.nuda, U. bromivora, U. cynodontis, U. tritici, Tilletia laevis, Tilletia controversa Sporisorium reilianum and S. cruentum were diagnosed. The morphological characteristics and phylogenetic relationship of these fungi with other smuts are described. Conclusion: The smuts of poaceous plants in Markazi and Lorestan provinces include eight species of the genus Ustilago, two species of the genus Sporisorium and two species of the genus Tilletia.

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.

Khezri  M, Allahyari Igdir S, Aghazadeh Soureh Z (2021) Tomato bacterial diseases in West Azerbaijan province of Iran. Plant Pathology Science 10(1):86-96. Doi: 10.2982/PPS.10.1.86.

Introduction: Tomato is one of the most important and most widely consumed vegetable in the world. Tomato also is one of the most important products in West Azerbaijan Province of Iran, which plays an important role in the province's agricultural economy. Accurate bacterial disease diagnosis is the first and most important step in designation methods of disease management. Materials and Methods: Tomato farms in the suburbs of the province cities were visited and diseased plants were sampled. Bacteria were isolated and purified from patient tissues and identified based on phenotypic and molecular characteristics. The bacterial pathogenicity test was performed according to Koch principles. Results: Tomato bacterial pathogens in this province include Clavibacter michiganensis subsp. michiganensis, Xanthomonas vesicatoria, Pseudomonas syringae pv. tomato, P. syringae pv. syringae and Dickya chrysanthemi, agents of bacterial canker,  bacterial spot, bacterial speck,  syringe leaf spot and soft stem rot. Disease symptoms, phenotypic and molecular properties of pathogenic bacteria, previous reports on these bacteria from Iran and their distribution in different regions of West Azerbaijan Province are presented. Conclusion: These bacteria, with the exception of the tomato bacterial canker agent, are reported for the first time from West Azerbaijan province.

Introduction: Two soil-borne fungi, Fusarium oxysporum and F. solani, are the causes of important diseases of beans wilting and root rot. The best way to manage these diseases is to identify and cultivate resistant cultivars. This study was conducted to identify the reaction of nine Iranian beans cultivars to these two pathogenic fungi. Materials and Methods: Bean-diseased plants were collected from farms in Aligudarz city in Lorestan province, in western Iran, and F. oxysporum and F. solani were isolated from them in the laboratory. At first the pathogenesis of these fungi was investigated on a local cultivar. Then, the reaction of nine bean cultivars to them was determined in a completely randomized design experiment in the greenhouse. Results: Reaction of cultivars to F. oxysporum and F. solani respectively were, Dadfar red-bean with disease severity of 28.8 and 26.6%, Sayad red-bean  with 33.3 and 28.8%, Koosha pinto-bean  with 35.5 and 33.3%, White 247 with 40 and 37.8%, Pak white-bean with 46.6 and 46.7% and pinto-bean 492 with 48.8 and 46.7% respectively, were grouped as semi-sensitive. Saleh pinto-bean with a disease severity of 64.4 and 62.2%, Yaghot red-bean  with 77.7 and 80% and Almas white with 82.2 and 86.7% respectively, were determined as sensitive. Pearson correlation analysis also showed that there was a significant negative correlation between root length, fresh and dry weight of root with diseases severity. Conclusion: Six cultivars of Iranian beans vs Dadfar, Sayad, Koosha, White247, Pak and 492 are semi-sensitive to these diseases.

Introduction: Blight caused by Ascochyta rabiei is the most destructive disease of chickpea worldwide. Identification of agronomic and morphological properties of disease-resistant cultivars is necessary to set up a suitable chickpea breeding program. Materials and Methods: Twelve agronomic and morphological properties of 21 resistant, semi-resistant, and susceptible chickpea genotypes were investigated in a field experiment in a randomized complete block design with six replications in one agronomic year in western Iran. Results: All genotypes were divided into three main clusters based on the UPGMA dendrogram. The lowest yielding genotypes were located in cluster II and IDDMAR-2012-32 genotype was susceptible to disease and desi-type in this cluster. The genotypes with the highest yield were placed in cluster III, and the genotype Gebres 419-2 was resistant to the disease and the desi-type in this cluster. Among the Kabuli-type genotypes, ILC482 was included in cluster III as a high-yielding and semi-disease-resistant cultivar, and low-yielding FLIp-02-65C and FLIp-01-164C lines along with disease resistance were included in cluster I. Conclusion: Gebres 419-2 can be crossed with FLIp-02-65C or FLIp-01-164C to produce robust, high-yielding Kabuli chickpea varieties with large seeds.

Rezvanjoo M, Sadravi M, Khoshroo A (2021) Impact of an arbuscular mycorrhizal fungus on Fusarium wilt in three tomato cultivars. Plant Pathology Science 10(2):74-81. Doi: 10.2982/PPS.10.2.74.

Bahlooli S, Abrinbana M, Ghosta Y (2021) The effect of the mixtures of carbendazim, iprodione and tebuconazole on Sclerotinia sclerotiorum. Plant Pathology Science 10(2):40-49.  Doi: 10.2982/PPS.10.2.40.

Introduction: Soil-borne fungus Sclerotinia sclerotiorum or white mold is the cause of the destructive disease of root and stem rot of many plants. Chemical control due to the lack of highly resistant cultivars is the most important method in the pathogen management program in various plants. However, the repeated use of fungicides leads to the development of resistant strains in pathogen populations. The use of fungicides with different modes of action, especially those with a synergistic effect, is one the most important anti-resistance methods. Materials and Methods: In this research, the effect of different mixing ratios in pairs of carbendazim, iprodione, and tebuconazole fungicides and their possible synergistic activity on four S. sclerotiorum isolates were investigated in vitro conditions. For this purpose, the isolates were cultured on potato dextrose agar, containing different concentrations of fungicides mixtures, and EC₅₀ values and the synergy factors were then determined for different mixtures ratios. Results: Tebuconazole: carbendazim mixture in 1:7 ratio, with a synergistic activity, inhibited all the isolates growth, and carbendazim: iprodione mixture in 1:9 ratio showed a synergistic effect on three isolates. Conclusion: The mixture of tabuconazole: carbendazim in 1:7 ratio had the best synergistic activity, and inhibitory effect on the growth of all the pathogen isolates, so it has the potential to be used in the management program of S. sclerotiorum.

Introduction: Bacterial canker caused by Pseudomonas syringae is one of the most damaging diseases in apricots. This experiment was conducted to evaluate relative resistance to the disease in 22 selected local apricot hybrids including AD507, AD405, and HS731 which were recently released as Jalil, Parsi and Shanli. Material and Methods: Evaluation methods included artificial inoculation of two-year-old seedlings in an orchard and of cut shoots in the laboratory. Initially, the pathovar identity of localP. syringae strains were determined using LOPAT and GATTa tests and three isolates were used as inoculum. The inoculation was done in the seedling stem and after one year and 1.5 years, canker length was recorded. Result: The pathovar of all isolates was identified as P. syringae pv. syringae. The longest and shortest cankers were observed in AD1033 and AC113 with averages of 34.76 mm and 8.35 mm, respectively. The cut shoot bioassay was not practical for apricots. The hybrids were classified into four groups including highly resistant, resistant, moderately resistant, and susceptible. Conclusion: AD1033, AD1042, AD940, AD811, HS210, DM101, HS203 have been classified as susceptible and should not be used in breeding programs and orchard establishment/replacement. Jalil, Parsi, and Shanli were rated as resistant, and moderately resistant, respectively.

 Yousefi-Nayi J, Pordel A, Drakhshan A, Nazvar A (2021) Fusarium species the causal cumin wilt in the Khorasan-Razavi province of Iran. Plant Pathology Science 10(2):30-39.  Doi: 10.2982/PPS.10.2.30.

Introduction: Cumin is the second most popular spice worldwide after black pepper. It is planted with a large acreage each year in Iran, especially in the Khorasan-Razavi province (northeastern Iran). Fungal diseases have caused great loss to this precious plant every year. This study aimed to investigate and identify the causal fungi of chlorosis and wilting of cumin in the Khorasan-Razavi province. Materials and Methods: Yellowed and wilted cumin plants were sampled from Torbat-Heydarieh, Kashmar, and Roshtkhar suburban’s farms, and fungi were isolated, purified, and identified, from their diseased tissues. The pathogenicity test of isolated fungi was carried out on a local cultivar under greenhouse conditions. Results: Two Fusarium species, including F. oxysporum with the highest frequency and F. equiseti with the lowest frequency, were isolated from diseased cumin plants. Between 43 isolates of these fungi in the pathogenicity test, twenty-four isolates of F. oxysporum caused wilt, and nine isolates of  F. equiseti caused chlorosis and leaf fall, in the plant. Conclusion: F. oxysporum, and F. equiseti are known as the causal agents of cumin wilt and chlorosis in the Khorasan-Razavi province of Iran.

Imani S, Moosavi SMR, Zare R, Basirnia T (2021) Optimum substrate and carrier for Purpureocillium lilacinum and its effectiveness against Meloidogyne javanica on tomato. Plant Pathology Science 10(2):50-64.  Doi: 10.2982/PPS.10.2.50.

Introduction: The soil-borne root-knot nematode (Meloidogyne javanica) causes heavy losses in tomato plants every year. Their management by chemical nematicides is difficult, expensive, and may also kill soil beneficial microorganisms, so other safer methods should be used to replace them. Purpureocillium lilacinum is an important biological control agent against root-knot and cyst nematodes. This study was carried out to determine the appropriate substrate and carrier of this fungus and its effect on these nematodes in tomatoes. Material and Methods: P. lilacinum was propagated in vitro on seeds of millet, corn, alfalfa, and clover substrates and their spore production was assessed 10, 20, and 30 days after inoculation. The survival of the fungal spores was then examined in talc, kaolin, and corn cob powder as carriers for 12 months. The effect of the fungus in the mentioned carriers against Meloidogyne javanica on tomato was investigated in the greenhouse by means of a completely randomized design experiment. Results: The highest number of spores in one gram of substrate was produced on millet seed on day 30. The highest number of survived spores was detected in the corncob powder carrier at all 12 months of the experiment. The fungus on corn cob powder was able to control M. javanica to 95% was similar to the nematicide Flopyram. This formulation also had a superior effect in establishing the fungus in the rhizosphere and on roots, suppressing the growth parameters of nematode and increasing plant growth. Conclusion: The fungus reproduced well on millet seeds and could last longer if formulated on corn cobs powder. Therefore, corn cobs powder can be a suitable base to produce an effective powdered product against M. javanica.

Vahabi S, Charehgani H, Abdollahi M, Rezaei R (2021) Response of eight melon cultivars to Meloidogyne javanica. Plant Pathology Science 10(2):65-73.       Doi: 10.2982/PPS.10.2.65.

 Introduction: The Root-knot nematodes (Meloidogyne spp.) are one of the most damaging plant pathogens with a wide host range and cause major losses to agricultural crops. The use of resistant cultivars is considered a safe, economical, and effective method to control these nematodes. Materials and Methods: In the present study, eight melon cultivars namely Ahlam, 105, Tracey, Ronak, Deltagrin, Mac, Holar, and Veno were evaluated for their response to M. javanica. The seeds were planted in 2 kg pots and maintained under natural conditions in Khormuj city, Bushehr province. Seedlings at the four-leaf stage were inoculated with 5000 eggs and second-stage juveniles. The factorial experiment was conducted in a completely randomized design with five replicates. Sixty days after nematode inoculation, the plants were harvested and the plant growth and nematode population indices were evaluated. Results: The results showed that the nematode reproduction factor was significantly lower in Ronak, Deltagrin, and Veno than in the other cultivars. No significant difference was observed in shoot fresh weight of nematode inoculated and non-inoculated plants of Ronak cultivar. Conclusion: Ronak, Delta-green and Veno cultivars are less susceptible to M. javanica.