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In order to study the role of Pythium species associated with cantaloupe root and crown rot, samples were collected from infected fields in different areas of Khorasan Razavi province during 2009-2010. The Root pieces were washed and cultured on CMA-PARP medium. The pythium isolates were then purified by hyphal tip method and identified based on van der Plaats-Niterink mycological key. The pathogenic species were identified as Pythium aphanidermatum, P. ultimum var. ultimum, and P. deliense. The pathogenicity of isolates on cantaloupe seedlings was tested under greenhouse conditions by using wheat grain inoculum. The results indicated that P. aphanidermatum was the most prevalent species and was recovered in all the regions. P. ultimum was isolated from Neyshabour, Fariman and Mashhad whereas P. deliense was detected in Khaaf. This to our knowledge, is the first report on occurrence and distribution of Pythium species causing root and stem rot on cantaloupes in Khorasan province.

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Rhizoctonia solani is the most serious problem on sugar beet Beta vulgaris L. grown in North Dakota and Minnesota. Picoxystrobin, a quinone outside inhibitor, and penthiopyrad, a succinate dehydrogenase inhibitor, were used alone and in combinations for controlling R. solani AG 2-2 IIIB on sugar beet under greenhouse conditions of 22 ± 2 °C and a 12-h photoperiod. Fungicides were applied in-furrow at planting, followed by inoculation with R. solani grown on barley seeds. The experimental design was a randomized complete block with four replicates and the experiment was repeated three times. Stand counts were taken and roots were evaluated for symptoms using a 0 to 7 scale 21 days after inoculation. Analysis of variance was conducted by the SAS general linear model, and Fisher’s protected least significant difference at α = 0.05 was used to compare treatment means. Fungicides used alone and in mixtures provided effective control of R. solani, which had significantly greater percent survivors than the inoculated check. This research demonstrated that picoxystrobin and penthiopyrad have the potential to be used for providing control of R. solani on sugar beet.  

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In recent years, biological control has become a promising and ecologically friendly alternative to chemical control in the management of soil-borne plant diseases and several biological control agents have been introduced as potential bio-fungicides. The aim of this study was to investigate different biological control agent consortia against Rhizoctonia solani root rot disease of common bean. Bacillus pumilus INR7, Trichoderma harzianum and Rhizophagus intraradices were used individually or in combination. There were two application methods: simultaneous application of biocontrol agents with the plant pathogen, and pre-inoculation of biocontrol agents one month before the pathogen. Treatments containing B.pumilus INR7 were the best treatments for suppression of the disease in the simultaneous application method, where B. pumilus INR7 + T. harzianumreduced the disease up to 54%. However, in pre-inoculation method T. harzianum alone was the only treatment that reduced disease severity up to 49% compared to the infected control; other treatments did not haveany significant effect on disease severity. In current study, combination of T. harzianum and R. intraradices was unable to decrease disease severity and improve plant growth. This phenomenon was common in both simultaneous and pre-inoculation experiments. However, results showed that B. pumilus INR7 and R. intraradices were compatible with each other. Their combination not only decreased the disease, but also improved the dry weight of common bean in both application methods. Our results revealed that B. pumilus INR7 had positive interaction with T. harzianum. This combination increased their ability to suppress root rot disease and improve plant health, significantly. Overall, combinations of biocontrol agents have good potential to be applied in modern agriculture, but such combinations need to be checkedin advance for their compatibility in greenhouse and field experiments.

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Analysis of genetic diversity of Fusarium verticillioides populations concludes different levels of information in management of crown and root rot disease in corn farms. Simple sequence repeat (SSR) markers were used to determine genetic structure and estimate genetic diversity in 77 F. verticillioides isolates from major producing areas in Ilam province, Iran such as: Dehloran, Mosiyan, Dasht Abas, Mehran, Eivan, Holeylan and Darreh Shahr during 2016 - 2017. Nine microsatellite (SSR) primer pairs revealed that the average number of alleles in populations were 34, the number of alleles in populations varied from 27 alleles in Dehloran and Mosiyan as the lowest to 40 alleles in Darreh shahr as the highest. Observed alleles (N_a) number and effective number of alleles (N_e) were higher in Mehran (N_a = 1.860; N_e = 1.463) compared to other populations. The genetic diversity (H_e) was higher in Holeylan (H_e = 0.284) and Shannon's information index (I) was also higher in Mehran (I = 0.436) but lower values were estimated for Mosiyan (H_e = 0.195; I = 0.303). The lowest genetic distance was found between Dehloran and Mosiyan (0.013) while the highest genetic distance was revealed between Dehloran and Darehshahr (0.139). Total gene diversity (H_t) and gene diversities between subpopulations (H_s) were estimated at 0.292 and 0.249 respectively. Gene diversity attributable to differentiation among populations (G_st) was 0.147, while gene flow (N_m) was 2.890. Cluster analysis based on UPGMA showed the lowest genetic distance between Dehloran and Mosiyan and then Dasht abas. The dendrogram indicated a high genetic distance between Darehshahr and the six remaining populations. Results from this study will be useful in breeding program of crown and root rot resistant cultivars and developing control methods for this disease. 

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Three Trichoderma harzianum isolates, were evaluated for their antagonistic effect on Rosellinia necatrix causal agent of white root rot (WRT). According to in vitro evaluations, T. harzianum T20A isolate showed the most pathogen growth inhibition. The inoculum of T20A isolate was applied to control WRT disease on four commercial apple rootstocks: Malling (M7, M25) and Malling Merton (MM111, MM106) in greenhouse experiments. Root rot and leaf fall indices were measured 70 days after pathogen inoculation. The biocontrol agent had a significant effect (p < 0.01) on the reduction of pathogen indices but the effect of rootstocks was not significant. Root rot reduction on MM111, MM106, M25 and M7 rootstocks were 63.84%, 61.13%, 28.63% and 17.47%, respectively. The antagonist also caused reduction of leaf drop symptom on MM106, M7, MM111 and M25 infected apple rootstocks by 57.4%, 56.06%, 44.09% and 40.24%, respectively. Disease indices were also measured for fungicide treatment and the results were compared with disease indices in antagonist treatments. The most biological control was observed on MM111 (63.84%) and MM106 (57.4%) according to the reduction in root rot and leaf drop, respectively. The reactions of apple rootstocks to WRT were also evaluated. The results showed that all the rootstocks were susceptible to WRT in the greenhouse condition. The MM106 rootstock which showed 100% root rot and 78% leaf drop was the most susceptible and M7with 43.5% root rot and 84.56 leaf drop was the least susceptible in our experiment. This was the first study of reaction and biocontrol of white root rot disease on apple commercial rootstocks in Iran and the results suggest a better insight to disease management either by integrating resistance and biocontrol measures or replacing chemical control by antagonist application to soil.

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Sesamum indicum L. is an important oil seed in Iran which is cultivated as summer crop in alternation with cereals and cucurbits, playing an important role in sustainable agriculture. Sesame wilt disease caused by Fusarium oxysporum f. sp. sesami is one of the limiting factors in its cultivation. Application of genetic improvement of disease resistance is one of the effective strategies to solve the disease problems in sesame. In this project, the partial resistance of 24 genotypes including, some commercial cultivars and promising lines were tested against Fusarium wilt disease. The experiments were conducted in three different conditions (greenhouse, micro plot and field). In greenhouse and micro plot experiments, artificial inoculation was used while in field experiment, no artificial inoculum was used. For evaluating results, the infection percentage (wilted plants) was recorded on a scale of 1-6 scoring system. The results showed that in artificial inoculation conditions, none of sesame genotypes were immune. Infection mean percentages of sesame genotypes were calculated to be 58.34, 28.6 and 15.96, in greenhouse, micro-plot and field, respectively. Total results of the three experiments showed that 29.1% of the sesame genotypes (JL1, Jl14, JL10, JL11, JL13, Jl18 and Darab1) fell in resistant (R) category and 37.5% of the genotypes (JL2, Varamin37, Local, Yekta, JL29, JL16, JL6, JL14-1 and Darab2) fell in moderately resistant (MR) group. The resistant and moderately resistant genotypes can be used for breeding programs and development of resistant varieties, however further efforts are needed to identify highly resistant genotypes from among more native germplasms via screening program.

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Root and crown rot of wheat is caused by the fungus Gaeumannomyces graminis var. tritici. "Take-all" is an important disease affecting wheat, and its incidence has been reported in several provinces of Iran. To identify resistant cultivars, bread wheat germplasm should be evaluated. To evaluate bread wheat germplasm in response to Iranian isolate fungus (T-41) of Gaeumannomyces graminis var. tritici, 333 genotype of bread wheat, collected from different locations of Iran and other countries were evaluated to take-all in greenhouse conditions. Two experiments were conducted, the first with 89 and the second with 244 genotypes. The measured traits were amount of root and crown infection, disease intensity, wet and dry biomass, and height of shoots. Analysis of variance and means comparison for the parameters indicated that in the first experiment, two genotypes were resistant to the disease, and the rates of disease intensity in these genotypes were 0.13 and 0.06. In the second experiment, five completely resistant genotypes were identified with disease intensity ratings of '0'. The identified resistant genotypes screened from both experiments were re-evaluated, and the results were the same. Mean comparison between winter and spring types for dry weight and disease intensity showed that winter wheat is more resistant than spring type. The results of this research showed that there is resistance resource to take-all (T-41 isolate), in this germplasm.Since the experiment was conducted in greenhouse conditions, these genotypes should be tested against this disease in infected conditions at field. 

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Monosporascus cannonballus and M. eutypoides are the causative agents of melons’ root rot and vine decline, with little knowledge about their mechanisms of infection. M. cannonballus secretome was isolated and subdivided into two fractions based on molecular weight (smaller and larger than 10 kDa), and further separated via high voltage paper electrophoresis and SDS-PAGE, respectively. Large cell-free filtrates of the fungus were found to contain biologically active proteins that were further characterized via mass spectrometry and revealed to be α-1,2-mannosidase and serine protease. Meanwhile, biochemical analyses of low molecular weight compounds were suggestive to be similar to marasmines. Both fractions were capable of inducing phytotoxicity, once infiltrated into the melon leaves. This is the first report of phytotoxic compounds isolated from M. cannonballus contributing to disease induction in melon plants.