جستجوی مقالات مرتبط با کلیدواژه « آلترناریا » در نشریات گروه « کشاورزی »

Tomato early blight caused by Alternaria alternata, A. tenuissima and A. solani, occurs in a wide range of environmental conditions. Effectiveness of fluxapyroxad+difenoconazole (Dagonis® SC12.5%), tetraconazole+azoxystrobin (Affiance® SC17%) and mandipropamid+difenoconazole (Carial Star® SC 50%) fungicides were evaluated in the control of tomato early blight disease in comparison with boscalid+pyraclostrobin (Signum® WG33.4%) fungicide. Dagonis® at the rates of 800, 1000 and 1200 ml/ha, Affiance® 450, 600 and 750 ml/ha, Carial Star® 400, 550 and 700 ml/ha and Signum® 500 gr/ha and the control group (no fungicide application). The experiments were carried out under the field condition in Fars and Hormozgan provinces, and under greenhouse condition in Alborz province. The disease severity index and area under the disease progress curve were calculated. The results showed that Affiance® at the rates of 600 and 750 ml/ha with 48-82% efficacy, Dagonis® at the rate of 1200 ml/ha with 50-70% efficacy and Signum® at the rate of 500 gr/ha with the efficacy of 48-75% were effective in controlling tomato early blight disease. Although Carial Star® fungicide with the amount of 700 ml/ha was less effective (45-55%) as compared to aforementioned fungicides, but its average efficiency can be justified. Therefore, Affiance®, Dagonis® and Signum® fungicides, at the rates of 600, 1200 ml/ha and 500 gr/ha, respectively, and Carial Star® fungicide (in the early stages of the disease) at the rate of 700 ml/ha are recommended to control tomato early blight disease.

Early blight disease on potato is caused by Alternaria solani and A. alternata. The damage rate of this disease is variable and has been reported between 5-78%. In this study, the effect of Propamocarb+fenamidone SC45%, Chlorothalonil WP75%, Azoxystrobin+difenoconazole SC32.5%, Boscalid+pyraclostrobin WG33.4%, Cymoxanil+copper hydroxide, Sodium bicarbonate, Calcium chloride, Cang Mei and Pars Basil in the laboratory and greenhouse was investigated. Generally, all of these treatments inhibited mycelial growth of A. solani and A. alternata. Azoxystrobin+difenoconazole and Boscalid+pyraclostrobin with concentration of 30 ppm and 100 ppm, respectively with 99% had the highest of percentage inhibition on the growth of A. alternata mycelium. The lowest effective treatment in mycelial growth inhibition of this species was Cymoxanil+copper hydroxide with concentration of 150 and 200 ppm. In greenhouse, Azoxystrobin+difenoconazole with concentration 1/1000 and Pars Basil with concentration 1/100 were the most and the least effective treatment in disease severity index of A. alternata, respectively. Azoxystrobin+difenoconazole, Sodium bicarbonate and Boscalid+pyraclostrobin with concentration 30, 20000 and 100 ppm, respectively decreased the growth of A. solani mycelium by 99%. Cymoxanil+copper hydroxide with concentration 150 and 200 ppm as the lowest effective treatment, inhibited the A. solani mycelium by 26%. In greenhouse, Azoxystrobin+difenoconazole and Boscalid+pyraclostrobin with concentration of 1/1000 and 0.5/1000, respectively decreased the disease severity index of A. solani by 100%. Cang Mei with concentration 1/100 decreased the disease severity index of this species by 5% with no difference with the control.

Application of chemical fungicides is the primary method of tomato early blight disease management in Iran. In this study, the efficacy of CangMei biofungicide in doses of 0.75, 1 and 1.25 ml L–1 were assessed on the control of this disease alongside with Iminoctadine Tris and control without the use of fungicide. The experiment was carried out in Fars and Khorasan Razavi provinces according complete randomized blocks with five treatments and four replicates. The first spraying was performed after flowering stage, the second one was after the first symptoms of the disease was observed and repeated every 7 days up to 5 times. The effects of pesticides were assessed six times on the development of the disease on the leaves based on disease severity and the data was analyzed using SAS software. The results showed the best treatment to control of tomato early blight disease was Belkute®. Cang Mei bio fungicide in dose of 1.25 ml L–1 had the greatest effect among examined doses and reduced Area under disease progress curve (AUPDC) 30.16% and 33.21% in Fars and Khorasan Razavi respectively. Due to the destructive effects of chemical fungicides, Cang Mei could be recommended in dose of 1.25 ml L–1 to produce healthy crop..

S Saffron (Crocus sativus L.) a perennial herbaceous is one of the most important crops. It is a valuable ketchup and its demand for consumption has been increased due to many medicinal and pharmacological applications. Saffron is a male sterile and can be propagated only by its corm and produces daughter corms. Cultivation of saffron is challenged by biotic stresses and corm rot as a biotic stress, is one of the most destructive diseases subterranean organs. Because of the insufficient information about corm rot etiology, investigation and identification of harmful agents is essential. Different pathogens such as fungi affect growth of corm and identification of these fungi is critical in cultivation of saffron. Occurrence of saffron corm rot has been reported from many countries and various microorganisms such as Fusarium, Rhizoctonia, Sclerotinia, Penicillium, Aspergillus, Bacillus and Burkhulderia have been isolated from rotted corm of saffron. The present study was conducted to identify fungi associated with corm of saffron in Khorramabad.  Infected corms of saffron were randomly collected from different regions of Khorramabad in Lorestan province (10 regions). The infected tissues were surface-sterilized with sodium hypochlorite (5%) for 1 min, and washed three times by sterile distilled water, dried on sterile filter paper and directly placed on the surface of potato dextrose agar medium. The PDA plates were incubated for 7 days at 25±2°C and then were purified using single spore method. Morpho-cultural characteristics of fungi were studied on carnation leaf agar and potato carrot agar media. Microscopic measurement and images of reproductive structures were carried out under a Nikon microscope. Pathogenicity test was conducted to evaluate the ability of isolates to colonize saffron corms. Conidial suspension was prepared from cultured isolates on potato dextrose broth medium and adjusted at a concentration of 1×106 conidia/ml. To inoculation, saffron corms were submerged in the conidial suspension, then planted in an aseptic soil and maintained for 4 weeks under controlled conditions in a greenhouse with 23 ± 2°C and 70% relative humidity. The disease incidence and severity was inspected daily and finally Koch’s postulates were tested. Totally, 58 isolates were collected and four species including of Alternaria alternata, Fusarium solani, F. acuminatum and F. oxysporum were isolated and identified on the basis of morphological characteristics. The A. alternate (25 isolates) and F. acuminatum (4 isolates) were the most and the least frequent respectively. According to the pathogenic test under the controlled conditions, F. oxysporum was the most aggressive and A. alternate was weakly pathogenic. There was not previous report of incidence of F. acuminatum and F. solani on saffron corm from the world and Iran respectively. The results of this research are in agreement with previous studies that showed corm rot is a major challenge in saffron cultivation. Corm rot is a complex disease and frequency, diversity and distribution of pathogens may be different due to cultivar type, agricultural practices, and climatological parameters. However, Fusarium spp. are the main agent of corm rot and F. oxysporum is the most predominant in saffron growing areas of the world. Moreover, Fusarium spp. have been reported as serious pathogen of subterranean organs of many crops such as potato, rice, wheat, and barley.  The results of this study showed that corm rot is a serious constraint in saffron production. Although A. alternata was the most frequent species in rotted corms, Fusarium spp. especially F. oxysporum were more aggressive and virulent on saffron. In addition, isolating saprophytic fungi such as Aspergillus, Penicillium and Rhizopus in our research showed that saffron corm is potentially exposed to infectious by varous fungi. Etiology of saffron corm rot is essential and results of this study can be helpful in management of saffron cultivation.

Trichoderma species are the main causes of decomposition and decay of agricultural residues and are considered for the control of plant pathogens, especially fungi and nematodes in the world. Trichoderma species have the ability to produce microbial enzymes such as xylanases, which are used in the paper and food processing industries. These enzymes improve the digestibility of nutrients in certain diets in ruminants and poultry, where there is no digestive enzyme that can digest the complex carbohydrates in the cell wall. These enzymes have the power to digest and hydrolyze these substances. South khorasan province due to hot and dry climate, water shortage and successive droughts, saline water in agriculture, pests and diseases, soil with low fertility for planting irrigated wheat needs cultivars resistant to these stresses. Narin cultivar is the latest cultivar introduced for this province. The characteristic of this cultivar are more compatibility with salinity stress areas and relative maturity with other wheat cultivars.
In order to investigate the effect of simultaneous use of Trichoderma harzianum and plant mulch on yield and physiological characteristics of wheat of Narin cultivar and its effect on the interaction of this cultivar with Alternaria alternata in 2019-2020 in Birjand Faculty of Agriculture Research Farm an experiment asComplete randomization block design was performed with four replications. Treatments included control (without application of Trichoderma), Trichoderma as soil application, Trichoderma as leaf application in granulation stage, Trichoderma application as soil and leaf application in granulation stage. In the granulation stage, each experimental unit was divided into two parts and Alternaria leaf spot pathogen treatment at two levels (inoculation in the granulation stage and without inoculation) was considered as a sub-factor in the experiment. The purpose of using the pathogen treatment was to evaluate the effect of Trichoderma in the presence of the pathogen. This fungus was prepared from the archives of the Plant Pathology Laboratory of Birjand University of Agriculture, which had previously been isolated from the wheat of this province. To inoculate this pathogen, a suspension with a concentration of 106 spores per ml of A. alternata was used from a 7-day fungus colony on PDA medium and its effect on physiological traits (including total phenol, chlorophyll a, chlorophyll b, carotenoids, total chlorophyll) were investigated. To investigate the effect of different applications of Trichoderma on Narin cultivar from another part of the plot without pathogen treatment was analysis of growth traits, yield and yield components including chlorophyll index, including green and dry stem height, spike length, weight, grain yield, biological yield, number and weight of grains per spike, spikes number and weight per unit area were measured.
The aim of using pathogen treatment was to evaluate the biological control of Alternaria wheat leaf spot agent by T. harzianum in different methods by using Trichoderma in the presence of Alternaria in comparison with the absence of Alternaria and its effect on physiological traits (including total phenol, chlorophyll a, Chlorophyll b, carotenoids, total chlorophyll) were evaluated. No symptoms of necrosis or leaf chlorosis were observed after pathogen inoculation. Analysis of physiological traits (total phenol, chlorophyll a, chlorophyll b, carotenoids, total chlorophyll) showed that only the simple effect of inoculation or non-inoculation of Alternaria with Trichoderma significantly different (P <0.05) in terms of total phenol content. Due to the presence of Alternaria as a pathogen, it may lead to a reaction of the plant's defense system, and Trichoderma can also increase phenolic compounds to counteract the pathogen. Analysis of growth traits, yield and yield components showed that Trichoderma treatment had no significant effect on any of them.
This study, for the first time showed that A. alternata can cause disease on wheat Narin cultivar. Also, this research studied the effect of T. harzianum on physiological and functional characteristics of wheat Narin cultivar and results demonstrated that T. harzianum can have little effect on these characteristics of Narin cultivar. Concomitant use of Trichoderma in soil and leaves had a greater effect than separate application in roots or leaves. Also, according to other research, the effect of trichoderma varies depending on the environmental conditions including temperature and humidity, soil texture and structure and the type of wheat cultivar.

Silybum marianum (L) Gaert.) Is a member of Asteraceae family, and silymarin is known as a valua effective substance in the plant, which is used to treat a number of diseases, such as liver disease. Chalcone synthase is one of the key enzymes in the production of silymarin. The fungal endophytes live in the tissues, without infection, and have a beneficial effect on the production of secondary metabolites of plants. Recently, several endophytic fungi from milk thistle (Silybum marianum (L) Gaert) have been isolated and studies were the chemical and molecular on its fungus has been considered. Therefore, this study aimed to isolate endophytic fungi from the seeds of milk thistle plant, and comparing the production of fungi and plant silymarin, as well as investigating the Chalcone synthase amino acid sequences associated with the L Silybum marianum and several other fungi from the NCBI database (http: //www.ncbi.nlm.nih.gov).

Therefore, this research was carried out to isolate endophytic fungi from the seeds of milk thistle plant, and to compare the production of fungal and plant silymarin. For this purpose, milk thistle seeds were collected from the area of Sari Agricultural and Natural Resources University and after disinfection, They sterilized in conditions, cultivated on MS medium. After appearance of fungi in the culture medium, the fungi were transferred to the PDA medium under sterile conditions the next for purification to WA medium. Fungal growth isolates were transferred to PDB medium and after 10 days of silymarin extraction Molecular identification of endophyte fungi isolates was performed by amplification of ribosomal areas, then the Alignment of the obtained sequence with the sequences on the NCBI site was compared with BLAST online software and identified with phylogeny tree of endophytic fungus. Investigate the bioinformatics of Chalcone synthase in L. Silybum marianum and several other fungi species,is use the NCBI database, was obtained by comparing domains and similar positions of Chalcone synthase, and was Investigating with the clustalo uniprot database. Then it was analyzed with CLC Genomics Workbench5.5.2 software and their specifications table was drawn up. The phylogeny tree of these sequences was drawn using the Mega7 software, using the Neighbor- joining

The results of high performance liquid chromatography confirmed the silymarin production of fungi. The amount of silymarin for leaf samples of intact plant was 33.079 ppm and for the in vitro grown plant was 17.183 ppm and for the endophyte fungus was 7. 29 ppm. Using ITS, molecular identification of isolates was carried out and its species was identified as Alternaria alternata. Also, analysis phylogenic relationship of chalcone synthase, as a key enzyme for production of silymarin, between milk thistle and a few fungi showed its closest proximity to to Alternaria sp.

The study of the production of silymarin in fungi isolated from the seeds of milk thistle , in vitro and in vivo plants, along with the bioinformatics study of the pathway of production of Chalcone synthase enzyme, determined the role of endophytic fungi in the production of silymarin. The fungal isolate was also able to produce silymarin in laboratory conditions

Early blight incited by Alternaria spp. is one of the destructive diseases of tomato which causes considerable crop yield losses. Biological control of the disease with epiphytic fungi as phyllosphere competent microorganisms is a suitable alternative to chemical pesticides. In order to isolating the fungi, healthy tomato plants were collected and small pieces of leaves and stems were placed in distilled water on a shaker and the aliquot was cultured. In search for biocontrol strains, isolated fungi were screened against the fungal pathogen (Alternaria alternata SN1–1) using dual culture as well as the volatile and non–volatile metabolites tests in vitro andeffective isolates were selected to study their efficacy on disease control under greenhouse conditions. Conidial suspension of epiphytic fungi was sprayed two times on the aerial parts of the plant in greenhouse. Two weeks after inoculation of the pathogen, the disease severity was evaluated based on a 0–9 scale. Results of screening test showed that epiphytic fungi inhibited the mycelial growth of the pathogen in various degrees. Maximum inhibition in dual culture, volatile and non–volatile metabolites tests were 70%, 53% and 68%, respectively. In greenhouse, the least disease indexes were recorded for the isolates F1–22 and P4––1 (81.4% disease control) together with P1–1 and P2–1 (74.4% disease control). Isolates F1–22, P4–1 and P2–1 identified as Trichoderma harzianum and isolate P1–1 identified as Trichoderma longibrachiatum.

The Lysin motif in receptor-like kinases (LysM-RLKs) bind to chitin or chitin components of the fungal pathogen cell wall to perceive their invasion. To study the LysM-RLK domains of potato genome involved in Alternaria solani response, the putative LysM-RLKs were bioinformatically assessed, sequenced and their expression levels were measured in a susceptible (Russet Burbank) and relatively resistant (F06037) genotypes, following inoculation of the pathogen. A total of 35 putative LysM-RLKs were detected in potato genome, of which 26, 5 and 4 LysM-RLK had none, one and two LysM motifs, respectively. Among 9 receptors containing LysM-RLK domains, two proteins showed a significant overexpression following A. solani infection.
PGSC0003DMP400061331 protein with two LysM motifs had a higher expression level than PGSC0003DMP400060418 protein with one LysM motif. Both proteins had 98% and 81% coverage with Arabidopsis thaliana CERK1 protein, respectively. Multiple sequence alignment (MSA) of LysM motifs from both proteins of two potato genotypes with that of Arabidopsis thaliana CERK1 revealed no difference between genotypes with respect to LysM motif sequence. Interestingly, the LysM motifs from PGSC0003DMP400061331 protein had an “NRD” insertion as compared to its second LysM motif, PGSC0003DMP400060418, and Arabidopsis taliana CERK1 LysM motifs. Such changes may have occurred through deletions or duplications. Alteration of DNA sequences by genome editing methods may shed light on the role of these genes in the field of resistance or susceptibility to A. solani leading to generation of resistant transgenic plants to devastating fungal diseases.

In order to investigate effects of different fungicide spraying treatments on soybean seed quality, a split plot experiment was conducted in a randomized complete block design with three replications in research field of Gorgan University of Agricultural Science and Natural Resources in 2016. Two spring (May 28) and summer (July 10) planting dates performed at main plots and fungicides spraying including benomyl, mancozeb, propiconazole, methyl thiophanate, carbendazim and control in two stages R3 and R6 were done in sub plots. Germination, accelerated aging, electrical conductivity, and seed health tests were used to evaluate the quality of seeds. Two fungi Alternaria sp. and Fusarium sp. spread were observed in seed lots, but lower prevalence for Fusarium sp.. Therefore, seed health was most affected by Alternaria sp.. The percentage of healthy seeds in spring sowing date was 21.48% higher than summer sowing date. All used fungicides (especially propiconazole and methyl thiophanate) significantly increased the health, germination, and vigor of seeds compared to control. The produced seeds in summer planting despite of more fungal infection, had higher seed germination and vigor than seeds of spring crops, because of exposing the seed development stages (R5-R8) to low temperatures. In the fact that, air temperature during seed development stages was more important in determining seed germination and vigor compared to pathogens. Therefore, in order to achieve high seed quality, it is appropriate to use summer planting with the utility of suitable fungicides such as propiconazole and methyl thiophanate at R3 and R6 growth stages.

Potato is one of the major Agronomic crops in Kurdistan province. Many fungi have been reported as the causal agents of tuber, crown and root rot and canker on potato plants. The objective of this study was to identify fungal agents associated with tuber, crown and root rot and canker of potato. Samples were collected from diseased plants in East of Kurdistan (Ghorveh and Dehgolan) during cropping season in 2014. Samples were first washed under tap water and then sliced to 0.5-1 cm pieces, surface sterilized and plated on general or selective culture media. In total 151 isolates were obtained from tuber, crown and roots of infected potatoes and purified using single spore or hyphal tip. Fungal isolates were identified based on morphological and sequence data of ITS, RPB2 and TEF loci. Finally, based on morphologic characters and DNA sequence data 10 species belonging to four genera were identified including Alternaria arborescens, A. alternata, A. atra, A. embellisia, Colletotrichum coccodes, Fusarium equiseti, F. redolens, F. tricinctum, Neocosmospora rubicola and N. haematococca. Among the identified genera, Fusarium with 93 isolates was the most frequent genus.

Cotton leaf spot disease caused by Alternaria alternata is one of the most common and important diseases in the cotton growth areas. The use of tolerant cultivars is one of the most economic means for the disease control. This study was conducted to evaluate the response of cotton cultivars against the fungus.In this research the fungus were isolated in seedling stage and purified in seedling stage from the cotton fields of Golestan province. and then fungus was detected using morphological data. Confirmed Alternaria species was performed using nucleotide sequence data of ITS – rDNA region and sequencing of the part of endo poly galacturonase gene. Accordingly, isolated Kb2 isolate with fungus
A. alternata were in one group phylogeneticlly. The relative resistance of seven cotton cultivars consist of Sepid, Golestan, B - 557, Sahel, Thermus-14, Bakhtegan and Armaqan to A.alternata Kb2were evaluated in greenhouse conditions and seedling stage with completely randomized design in three replications.The results revealed that the reaction of cultivars to disease were different, however, none of the cultivars showed high levels of resistance. Termus- 14 cultivar had the highest of leaf spot severity and B-557 and bakhtegan cultivars had the lowest of leaf spot severity. In other words, these two cultivars were introduced as the tolerant cultivars to leaf spot disease at seedling stage.

Early blight disease caused by Alternaria solani spreads well in abundance of humidity and the presence of water on the leaves. The early symptoms of disease are brown to black spots as concentric embowed rings. The fungal spores are distributed by wind and rain to healthy leaves. High humidity and temperatures between 18 and 25 °C, dew, rain and sprinkler irrigation increase its spread. The purpose of this study was to study the influence of meteorological variables (Temperature, Relative humidity and Precipitation) on spores’ population of early blight pathogen of potato and possible prognosis of disease in Kermanshah province during 2013-2014 crop seasons. To perform the study, potato plants were cultivated in Razi University farm and the symptoms of the disease were monitored continuously through the season. Besides, the number of fungi spores were also measured using a standard spore trap. On the other hand, two early blight prognosis empirical models were developed using on-site meteorological data and those obtained from nearby synoptic station. The correlation between the population of spores in the air and meteorological variables were worked out. The results showed that there exist a significant relation between the spore population and maximum-minimum air temperature (p= 0.01) and relative humidity (p=0.05). According to results of this study, the proposed model can be satisfactorily used for early blight early warning in western region of Iran.

Russian knapweed (Acroptilon repens L.) is a noxious perennial weed in the family of Asteraceae which caused various problems in field crops، pastures، grasslands and orchards. For collecting fungal pathogens from this weed، as biocontrol agents، a survey was carried out during 2011-2012 in Mashhad and Chenaran areas (north east of Iran). The isolated fungal agents from infected Russian knapweeds were purified. After primary studies، three isolates of Alternaria alternata، Fusarium oxysporum and Puccinia acroptili as the most effective fungal pathogen on Russian knapweed، were selected for host range tests and further studies. Supplementary studies were conducted to evaluate their effect on the target host at different concentrations consisted of 104، 105، 106، 107 spores ml-1. In a separate experiment، the influence of colorless or black plastic cover and dew periods included of 3، 6، 12، 18، 24، 48 hours on disease expression by P. acroptili was studied. In host range test of P. acroptili no any symptom was detected on wheat، barley، conola، sugar beet، tomato، potato، cucumber، green bean، maize and alfalfa whereas، two other isolates induced disease on some of the tested crops. P. acroptili reduced the dry weight of 4-week old seedlings of A. repens by 61%، compare with control. The most sever disease symptoms on seedlings of the target host was obtained from treating with P. acroptili spores at 107 spores ml-1 and 48 hours dew period under black plastic. This treatment، compared with 3 hours dew period under colorless plastic cover، reduced dry weight of A. repens seedlings by 40%، and disease progress curve on the weed was evaluated 24. 64%. Based on this research، P. acroptili could be considered as a promising biocontrol agent for Russian knapweed.

Effect of chlorothalonil (Daconil SC 725) and famoxadone + cymoxanil (Equation Pro WG %52. 5) fungicides in control of Early Blight disease of tomato were evaluated under field conditions. The experiments were carried out in a Randomized Complete Blocks Design (RCB) with eight treatments and four replications during two years in Karaj. Experimental plots inoculated with causal organism at the beginning of flowering stage. Spraying of plots was started by early symptoms seen and continued with 5، 7 and 10 days intervals. Disease Severity Index (DSI) assigned by Foliage Protection Percentage (FPP) with causal agent by using Horsfall and Barratt method، before each spraying، and the later assessing was done 14 days after last spraying. Yield of each plot was measured، and numbers of fruits for each plant were counted. Analysis of variance of two years data، were done at Randomized Complete Blocks Design (RCB) by SAS software، and means were compared with Duncan multiple range test. Area under the Disease Progress Curve (AUDPC) was calculated using five separate disease assessments data، and effects of treatments on disease progress were also studied. The results revealed that there were significant differences between treatments in DSI in all assessments، AUDPC and yield but there was no significant difference between treatments in number of fruits. Also the results for 5th assessment and AUDPC in both study years showed that Daconil SC 725 (3 L/ha) and Equation Pro (450 g/ha) with lowest mean based on DSI were the best treatments to control of Tomato Early blight disease. Daconil SC 725 (3 L/ha) and Equation Pro (450 g/ha) were decreased DSI by 80. 26 and 80. 6 percent in compare to control، respectively. In terms of mean fruit weight، Equation Pro (450 g/ha) and Daconil SC 725 (3 L/ha) were increased yield 65. 03 and 64. 17 percent in compare to control، respectively، and were the best treatments.