پوسیدگی طوقه و ریشه

Ten apple promising rootstocks (Azop(385), AZ × M9(285), AZ × M27(85), Azop(285), AZ × M9(185), Azop(286), Azop(386), M9op(387), B9op(87), Azop(486)) were evaluated for resistance to crown and root rot caused by Phytophthora cactorum based on a completely randomized design with six replicates. Fungal inoculum was applied around the crown of each rootstock. Three to seven months after inoculation, the response of hybrids to the fungus was assessed based on root rot (%), crown length rotted, and crown girdling. The highest percentage of root rot belonged to MM106 and B9op(87), and AZop(486) (with 41.3 and 32.7%, respectively). Maximum crown rot was measured on MM106 (83.9%), B9op(87) and M9op(387), respectively. The greatest crown circumference girdled incidence was on MM106 followed by M9op(387), B9op(87). Adjusted Selection Index of Ideal Genotype (ASIIG) was calculated based on ideal and non-ideal distance. The rootstocks of AZop(385), Azop(285), and Az × M27(85) with the index value of 0.948, 0.937 and 0.8884, respectively, had the highest desirability among all rootstocks. These genotypes received a better place compared to M9. The least desirability belonged to MM106, M9op(387) and B9op(87) with the index value of 0.395, 0.375 and 0.343, respectively. The dendrogram generated from ASIIG, classified Azop(285), Azop(385), Az × M27(85) and M9 (as standard resistant rootstock) with the minimum distance to the hypothetical ideal genotype in the same group. Furthermore, Azop(386), M9op(387), B9op(87) with MM106 (as standard susceptible rootstock) were grouped at non-ideal quarter. A larger distance was found between other hybrids and the hypothetical ideal genotype.

Crown and root rot are important diseases of different small-grain cereals, especially wheat and barley which are caused by soil-borne fungi Fusarium culmorum and F. pseudograminearum. For controlling such diseases, application of fungicides is inadequate, and cause hazardous effects for environment and living organisms. As an alternative strategy, screening of resistant wheat genotypes has been emphasised in the recent studies. This research was conducted to evaluate level of resistance of 66 cultivars/advanced lines of bread wheat and durum wheat to F. culmorum and F. pseudograminearum isolates in greenhouse and field conditions. These experiments were conducted based on completely randomized design with seven replications in greenhouse and randomized complete block design with 4 replications in field condition. The results showed that, 12 genotypes including C61 (C-87-18) and C62 (C-87-11), C38 (F06659G6-1), C43 (POLOVCHANKA/PEHLIVAN), C52 (McCormick/Trego), C37 (F06580G2-1), C35 (Prostor), C54 (VA01W-205/TX99D4628), C50 (GA951079-3-5/Neuse), C58 (Burbot-6), C53 (AWD99*5725/FL9547) and C34 (Gelibolu) were moderately resistant to F. culmorum and F. pseudograminearum isolates. These genotypes have potential to be incorporated into wheat breeding programs.

Iranian Pistachio is one of the most important horticultural product in export market. Crown and root rot caused by Phytophthora species is the most serious disease of plant, which annually destroys a considerable number of mature and young trees. This disease has been reported from all provinces of Iran. The pathogen is soil-borne and is distributed by sporangia or the released zoospores and infects the healthy trees. In the most Pistachio orchards, the key factors of disease development are the sensitivity of pistachio crown to Phytophthora and the flooding method of irrigation. The symptoms of the disease are include blight in early spring, drying of the green leaves during the growing season, gum exudation from the crown of tree  and the root rot. Gummosis can be successfully controlled by integrated disease management including orchard constructing in non-infected areas, using resistant or tolerant cultivars, using healthy rootstocks, improving the irrigation methods and avoiding the direct contact of water with tree crown, isolating the contaminated parts of the orchard from the healthy parts, using suitable fungicide, and biological control based on Trichoderma and Bacillus species.

In this study, the effect of some plant probiotic bacteria were isolated from salty and dry areas were investigated in control the fungus agent pistachio gummosis disease and growth stimulating properties. 200 bacteria isolates were isolated from rhizosphere and non rhizosphere areas of pistachio trees and weeds in the margins of gardens in Kerman province. Thirty isolates were able to endure the used salt tolerant. The bacteria isolates were investigated at the hypersensitivity reaction (HR) test. Three of them were eliminated due to positive result of HR and the other were studied more as antagonist agents. In the early stage the biocontrol ability of these isolates against the fungus causing pistachio gummosis diseases such as Phytophthora drechsleri were surveied. For this purpose, inhibition zone test (antibiosis) was performed that antagonist isolates showed significant effect on P. drechsleri growth. In the secondary stage, The ability of isolates to produce some biocontrol metabolites including protease, antifungal volatile compounds and hydrogen cyanide were evaluated. Growth stimulating characteristics of these isolates incloding amount of siderophore and IAA production were measured. soluble ability of insoluble mineral phosphate was surveied, too. The results showed from 27 studied isolates for growth stimulating properties, %80 at least had one of the PGPR properties. %64 of the isolates were productive of siderophore, %80 productive of IAA, %45 having solving ability of insoluble mineral phosphate. The isolates C16, F47 and G11 as superior isolates of this study in vitro were successful in controlling the disease.

The best cherry rootstock for Iranian nurseries and orchards is Prunus mahaleb (L.) Mill. Mahaleb is tolerant to lime-induced iron chlorosis and zinc deficiency. It is a good rootstock on light, calcareous soils and arid climates in Iran but sensitive to Phytophthora. Iran represents a significant source of germplasm of different fruit species, especially for those from the genus Prunus. Collection and research on P.mahaleb was initiated at the Horticultural Department of Khorasan Razavi Agriculture and Natural Resources Research and Education Center in 1997 for mahaleb cherry rootstock. Some researchers have reported pathogenicity of Phytophthora species (Banihashemi and Sartipi, 2004; Wilcox and Mircetich, 1985; Exadaktylou and Thomidis, 2005; Tomidis et al., 2008). This study was conducted to evaluate the susceptibility of 30 selected dwarf Mahaleb genotypes to P.nicotianae, P.citricola, P.cactorum and P. citrophthora under greenhouse and orchard conditions.
Material and In this study, the response of 30 selected dwarf Mahaleb genotypes (188, 171, 165, 162, 161, 155, 139, 136, 131, 120, 106, 104, 101, 100, 90, 194, 195, 199, 200, 224, 228, 247 , 249, 265, 266, 267, 268, 270, 272, 277) to disease caused by four species of the fungus Phytophthora root and crown rot were investigated under greenhouse and orchard conditions. Greenhouse experiments were performed based on Ribeiro and Baumer, 1977 and modified it by Feichtenberger et al., 1984. For evaluation the index disease was performed based on the method of Broadbent and Gollnow 1992. Orchard terials was laid out in the Toragh research station in Mashhad. Evaluation of genotypes and contamination based on Tomidis, 2001 was performed by measuring the area of necrosis.
In evaluating the reaction of young seedling dwarf mahaleb genotypes to four Phytophthora species under greenhouse conditions, results showed that four species of Phytophthora pathogens on all mahaleb genotypes but P.citricola, P.cactorum showed disease severity than P.citricola, P. nicotianae. In response assessment test seedlings in the greenhouse genotypes Mahaleb highest rate of infection to P.cactorum in genotype 277 and the lowest index of disease severity showed in genotypes 100, 188, 199, 200, 224 and 266, respectively. The highest and lowest number of leaves was counted on 199, 272 and 277 respectively. The least and highest shoot dry weight were related to 277 and 100 genotype respectively. The maximum and minimum disease severity to P.citrophthora revealed in 265 and 265, 100, 188, 194, 199 genotypes, respectively. The highest and lowest number of leaves was counted on 188 and 249 respectively. The least and highest shoot dry weight were related to 249 and 100genotype respectively. The least and highest root dry weight was measured on 265 and 100 genotype, respectively. In response assessment test seedlings in the greenhouse genotypes Mahaleb highest rate of infection to P.citricola in genotype 265 and the lowest index of disease severity showed in genotypes 100, 162, 171, 188, 199, 200,224, respectively. The highest and lowest number of leaves were counted on 100and 277, 272 respectively. The least and highest shoot dry weight were related to 272 and 100 genotype respectively. The least and highest root dry weight were related to 277 and 100 genotype respectively. The highest rate of infection to P.nicotianae in 120 genotype and the lowest index of disease severity were related to the genotype of 188 and 199. The highest number of leaves in genotype No.100 and the lowest number of leaves were belonging to genotypes 272 and 277, respectively. The least and highest shoot dry weight were related to 247 and 100 genotype respectively. The least and highest root dry weight were related to 265 and 100 genotype respectively. The results of the assessment of the two year old seedlings mahaleb genotypes under orchard conditions showed that four Phytophthora species had different degrees of disease symptoms. Phytophthora species in their ability to create the symptoms are different. The lowest level of necrosis is created by P.cactorum. The highest and lowest levels of necrosis of P.cactorum were measured in 267 and 162 genotypes, respectively. In P. citrophthora, the highest and lowest levels of necrosis were measured in 277 and 188 genotypes, respectively. The highest and lowest levels of necrosis of P. nicotianae were measured in 272 and 188 genotypes, respectively.
ConclusionThe results of the assessment Mahaleb genotypes to four species of Phytophthora in the orchard showed that the lowest level of tissue necrosis in genotypes of 106, 139, 162, 188, 195, 224, 266 and 270, respectively. Finally our results revealed that P.citricola, P.cactorum were pathogenic Phytophthora species and three mahaleb genotypes (266, 224 and 188) had highest potential resistance to P. nicotianae, P.citricola, P.cactorum and the P.citrophthora respectively.

Iran is one of the biggest sweet cherry producers in the world. Turkey, the U.S.A and Iran are among the major producers of cherry in the world. Mahaleb(Prunus mahaleb L.) is used as a principal rootstocks for sweet and sour cherries in Iran. Mahaleb is a good rootstock on light, calcareous soils and arid climates in Iran. Since pathogenic species, P.citricola, P.cryptogea, P.dreschleri, P.cactorum, P. syringae, P.cinnammomi, P.megasperma, P.cambivora on mahaleb been reported by different researchers (Sajadinejad et al., 2011) According to the pathogenesis of four species of P. nicotianae, P.citricola, P.cactorum and P.citrophthora on stone fruit trees in Iran and other countries, based on the hypothesis that the relative resistance to Phytophthora species in selected dwarf Mahaleb genotypes adapted to environmental conditions exist and can be introduced as resistant rootstocks to crown rot disease, this study was conducted to evaluate the susceptibility of 30 selected dwarf Mahaleb genotypes to P.nicotianae, P.citricola, P.cactorum and P. citrophthora. Sofar, the selection of resistant or tolerant to Phytophthora cherry rootstock, studies have not been done. Therefore, it is appropriate to introduce the cherry trees for planting in various parts of the country, the need to evaluate several species of Phytophthora resistance or tolerance to the grades mentioned above. Considering the history of the pathogenesis off our species of P. nicotianae, P.citricola, P.cactorum and P.citrophthora the stone fruits this study aimed to evaluate the reaction of 30 cultivars of dwarf Mahaleb to P.nicotianae, P.citricola, P.cactorum, P.citrophthora was carried out.
In this study, the reaction of 30 dwarf Mahaleb genotypes were investigated to disease caused by four species of the fungus Phytophthora root and crown rot. Excised twig, annual and perennial shoots to measuring resistance using laboratory methods. Excised twig, excised annual and perennial shoots assessment based on Jeffers et al., (1981) and Matheron and Mircetich(1985) respectively.
In evaluating the reaction of excised twig, excised annual and perennial shoots dwarf mahaleb genotypes to four species of Phytophthora, rot and discoloration symptoms were observed, All control shoots of Mahaleb genotypes were evaluated in this trial did not show any symptoms of discoloration and Phytophthora rot but shoots treated with four species of Phytophthora showed that different degrees of light brown to dark discoloration and decay. The results of the analysis of variance showed that the genotypes of disease progression on the tissues of all three types of excised shoots inoculated with four species of Phytophthora were difference statistically significant. Also, the results of comparing the length average of progression of symptoms (necrosis) on this experiment were as follows which are outlined below.
P.cactorum
On the test assessment the reaction of excised twig, excised annual and perennial shoots dwarf mahaleb genotypes, least amount of sensitivity to species belongs to genotype199 with an average contamination of 12.44%, 162 with an average contamination of 1.42% and 162 with an average contamination 0.01 %, respectively.
P.citrophthora
On the test assessment the reaction of excised twig, excised annual and perennial shoots dwarf mahaleb genotypes, least amount of sensitivity to species belongs to genotype 265 with an average contamination of 15.67%, 155 and 162 with an average contamination of 0.01% and 262, 228, 224 and 188 with an average contamination 0.01 %, respectively.
P.citricola
On the test assessment the reaction of excised twig, excised annual and perennial shoots dwarf mahaleb genotypes, least amount of sensitivity to species belong to genotype 124 with an average contamination of 11.80%, 100 with an average contamination of 0.60% and 266 with an average contamination 3.13 %, respectively.
P.nicotianea
On the test assessment the reaction of excised twig, excised annual and perennial shoots dwarf mahaleb genotypes, least amount of sensitivity to species belong to genotype 120 with an average contamination of 16.15%, 100 and 95 with an average contamination of 0.01% and 188 with an average contamination 0.87%, respectively.
There were significant differences between the genotypes of disease progression in the tissues of all three types of excised shoots inoculated with four Phytophthora species.
The results showed that, some mahaleb genotypes (100, 124, 155, 162, 188, 195, 199, 224, 266 and 265) have potential resistance to species P.nicotianae, P.citricola, P.cactorum and P.citrophthora, that can be considered in breeding programs.

During 2009-10, wheat fields in eight provinces of Iran including Tehran, Esfahan, Ardabil, Golestan, Mazandaran, Markazi, Qazvin and Zanjan were surveyed and samples were collected from plants showing crown rot disease symptoms. Fusarium species were identified based on morphological features and molecular markers (SCAR). Twelve Fusarium species including F. culmorum, F. pseudograminearum, F. equiseti, F. nygamai, F. proliferatum, F. oxysporum, F. solani, F. pseudonygamai, F. sambucinum, F. acuminatum, F. lateritium and F. verticillioides were identified. F. culmorum was the dominant species and had the highest (32%) frequency, followed by F. pseudograminearum (18%). Genetic diversity of 64 representative isolates of F. culmorum was studied using eight Simple Sequence Repeat (SSR) markers. There was a high level (0.81) of genetic diversity within the total population, where 89% of the variability was distributed within populations and 11% among populations. Number of alleles was between 7 to 22. In addition, there was significant difference among isolates in their aggressiveness. Isolates with a high level of aggressiveness from different geographical areas can be used for screening resistance to F. culmorum.

The aim of this research, identifying the fungi taxa associated with root and crown rot of walnut trees in Kermanshah. For this purpose, the soil around root of trees and root and crown samples of walnut trees showing disease were collected in different region in Kermanshah. The purified isolates were identified using morphological characters on the different culture media, asexual and sexual organ as well as growth rates at different temperatures. In this research, 13 isolates, belong to three species including Phytophthora cactorum, P. citricola and Pythium sp. were identified. Pythium sp. maybe is a new species, because characteristics of this species did not match completely with other recognized Pythium species. Pythium sp. (1) and Pythium sp. (2) isolated from diseased tissue and infected soil, respectively. Pathogenicity test of these species were performed on excised shoots and seedlings In vitro and In vivo, respectively. Results of In vitro indicated that the most disease extension was appeared by Phytophthora cactorum, but was placed in one statistical group with Pythium sp. (1). Phytophthora citricola and Pythium sp. (2) were placed in the following statistical group. Results of greenhouse experiment shown that, P. citricola and P. cactorum caused complete death of seedlings after 8 and 12 days, respectively. Pythium sp. (1, 2) after 14 days caused drying of stem and leaves and death of seedlings.

This research was performed to determine the host range of tomato isolates of Phytophthora capsici، among other common crops in Fars province. Seeds of tomato، squash، cucumber، melon، pepper، watermelon، pea، french bean، onion، carrot، corn، cantaloupe، eggplant، and wheat were sown in sterilized soil and kept in a greenhouse. Seedlings were inoculated by adding 50 ml of a zoospore suspension (1×105 spores per ml) of Ph. capsici onto the soil surface around the stem of each plant in the pot. Plants were kept in a growth chamber. Disease incidence was measured three times at 5، 10، 15 days post inoculation. Twelve of the tested plant species became infected with Ph. capsici and developed symptoms including crown and root rot، and yellowing، which led to plant death after two weeks. Ph. capsici was re-isolated from all symptomatic plants. Tomato، squash، cucumber، melon، pepper، watermelon، cantaloupe and eggplant were the most susceptible، while، pea، french bean، onion، carrot and sugar beet were less susceptible to the pathogen. Wheat and corn did not show any disease symptoms and were considered as non-hosts. The results of this study showed that common Poaceae crops in Fars province are non-host to Ph. capsici and can be used in crop rotation for disease management.

To identify Trichoderma isolates for potential biocontrol of crown and root rot in pistachio، 100 samples of soil taken from rhizosphere، fertilizer channels and from soil surface were collected from Kerman، Yazd، Khorasane Razavi and Semnan provinces during 2009-2011. Overall، 32 isolates of Trichoderma harzianum were obtained mostly from rhizosphere soil using either general or special environmental surroundings. The antagonistic potential of the isolates against P. melonis was screened using the dual culture technique. A total of 11 isolates were employed for further assessment of their capability to inhibit P. melonis، in various assays under in vitro and as well in vivo conditions. Overall، the results indicated that the incidecne of interactions through different mechanisms reduced mycelialy growth of P. melonis to different degrees، ranging from 38. 1 to 63. 6%، 25. 4 to 58. 7%، 50 to 89. 6% and 44. 7 to 71. 77% in the simultaneous vs non-simultaneous dual cultures، and volatile vs non-volatile compounds، respectively. In greenhouse experiments، and in mixed inoculations with Trichoderma harzianum strains and P. melonis it was observed that، root length and plant height increased respectively from 1. 5 to 2. 7 and from 1. 4 to 2. 1 times of inoculation with pathogen alone، as well as 1 to1. 9 of root length and 1 to 1. 6 times the plant height as compared with non-inoculated control plants. Incidence of T. harzianum isolates before، simultaneous with، and following pathogen inoculations (in pots) significantly influenced the mortality of seedlings with the respective ranges of 0 to 31%، 0 to 56%، and 12. 5 to 75%. This is the first report on the introduction of T. harzianum isolates to pistachio orchards، along with their interactions with gummosis (crown and root rot) causal agents.

The cucurbit damping off, root and crown rot caused by Rhizoctonia solani Kuhn are the most important diseases of these crops. In a survey of fields and greenhouses during 1384-1385 samples of cucumber, pumpkin, watermelon and melon, suspected of being infected by Rhizoctonia in Tehran, Mazandaran, Khouzestan and Isfahan provinces were collected and the fungus was isolated. In this study, 59 isolates of R. solani were recovered from soil, crown and roots of cucumber, pumpkin, watermelon and melon. Hyphae width ranged from 4.46 to 6.86 μm, and all of them were multinucleate. Anastomosis grouping showed that 81% of samples belonged to AG4 and the rest of isolates did not anastomose with either of the standards AG2 and AG7. The results of pathogenicity test showed that of the 59 recovered isolates, 97% were pathogenic, which in turn were classified in 10 separate categories based on their virulence. In this investigation two isolates of pumpkin and cucumber belonging to AG4 from Isfahan province appeared to be non pathogenic. This is considered to be the first report AG4 on pumpkin in Iran.