جستجوی مقالات مرتبط با کلیدواژه « گردو » در نشریات گروه « گیاهپزشکی »

Walnut (Juglans regia L.) is known as one of the most important dried fruits of the world. Chaharmahal & Bakhtiari Province, with approximately 7400 hectares, is one of the most important cultivation areas in Iran. Considering the rich fauna of ants in walnut orchards and their relation with walnut pests (such as Leopard Moth and aphids), this study was conducted in Shahrekord and Saman orchards during 2021-2022. Totally, 13 species belonging to 10 genera and three subfamilies, were collected and identified. Among them, Messor muticus (Nylander, 1849) and Tetramorium indocile Santschi, 1927 belonging to the subfamily Myrmicinae are reported for the first time from Iran, and Chaharmahal & Bakhtiari Province, respectively. Furthermore, this study revealed that Tapinoma karavaievi Emery, 1925, Lasius neglectus Van Loon, Boomsma & Andrasfalvy, 1990, and Crematogaster subdentata Mayr, 1877 have symbiotic relationships with walnut aphids and lecanium scales and are probably effective in the distribution and damage of these pests.

The major disease of Persian walnut is walnut blight caused by the bacterium Xanthomonas arboricola pv. juglandis. This disease limits walnut production in many regions of the world in particular those with warm and humid springs. All succulent tissues including recent shoots, fruits and catkins may be attacked but their sensitivity decreases over time. Symptoms on leaves begin as small, water-soaked spot that can expand to form angular necrotic lesions surrounded by a yellow hallo. Infection on the hull of the unripe fruits is initiates as a dark spot, which rapidly creates dark sunken lesions. If fruit infection occurs before shell hardening, the kernels are usually destroyed, infection after shell hardening results in dark kernels and poor-quality nuts, while the kernel is until consumable. The main current strategy for walnut blight control is to protect succulent tissues by copper-based sprays from bud-burst. However, multiple copper sprays do not always control the disease and there is the risk of development of copper resistant bacterial strains. Cultivation of resistant cultivars is the most practical, environmental friendly and economical approach for controlling of this disease. So far, there have not been any cultivar completely resistant or immune to this disease. However, variation in susceptibility level has been shown to occur, worldwide. The objective of this study was to determine leaf and unripe fruit resistance of Iranian promising walnut genotypes in response to controlled inoculation with X. arboricola pv. juglandis in orchard and laboratory conditions.

In this research, the relative resistance of leaf and unripe fruits to bacterial blight were studied in a number of promising walnut genotypes replicated during two years of 2015 and 2016. The local genotypes have been selected through massive surveys of native orchards in different provinces of the country. The main selective criterion for walnut selection was late leafing trait. In addition, correlation between leaf blight and unripe fruit blight severities were studied. The material included H1-7, H2-1, SHK2, Vina, Round de montignac (RDM), Lara, G4, G5, B10 and K15 genotypes and cultivars. From this material, KZ3, 88-2, 88-1 and G3 were registered and released in year 2019. Also, Serr, Chandler and Hartley cvs. were used as controls. A mixture of four local bacterial isolates originated from Qazvin, Karaj, Zanjan and Urmie was used as inoculum. The bacterial strains have already been characterized using different phenotypical and molecular tests. They were cultured on Nutrient Agar (NA) plates at 28 ℃. After 72 hours of cultivation, the colonies were suspended in distilled water; the concentration of the suspensions was read by spectrophotometer and after equalization, mixed and used as inoculum. Assessing leaf resistance was performed by spraying one year old grafted seedlings in glasshouse condition and lesion area was recorded 21 days after inoculation. Three leaves (contacting leaflets) of three seedlings were used per genotype. Assessing unripe fruit resistance was achieved by inoculating 45 days old fruits in laboratory condition and lesion diameter data was read 15 days after inoculation. 15 fruits per genotype were used and three lesions were created in each fruit. Statistical analysis of data was performed by Duncan Multiple test range using SAS software.

Based on the results, leaf and unripe fruit blight severities were different among different cultivars and genotypes in both years of evaluation. Combined analysis of blight severity data indicated that G3 (Alvand) and 88-2 (Persian) genotypes had the most leaf blight severity and thus, rated as the most susceptible, while Hartley cultivar had the least leaf blight severity and thus, as the most resistant. Based on combined analysis of data, H1-1 and SHK2 genotypes had the most blight diameters of unripe fruits and thus rated as the most susceptible and resistant genotypes, respectively. Leaves of newly released cultivars of Persian, Caspian, Alvand and Chaldoran were rated as susceptible, relatively resistant, susceptible and relatively susceptible, respectively. On the other hand, unripe fruits of Persian, Caspian, Alvand and Chaldoran were classified as resistant, resistant, relatively resistant and susceptible, respectively. Mean leaf blight severities were not different between the two years of study and also there was no difference between unripe fruit severities between two years of the experiment. No significant correlation was found between leaf blight and unripe fruit blight severities.

Walnut is one of the most important fruit trees in Iran, which is always exposed to pathogens, especially bacteria. The three most important bacterial diseases of walnut in Iran are bacterial blight (Xanthomonas arboricola pv. juglandis), skin cankers (Brenneria nigrifluens, Brenneria rubrifacians) and crown gall (Agrobacterium tumefaciens). Bacteriological characteristics and pathogenicity of pathogenic bacteria, methods of managing these diseases, along with suggestions for identifying resistant genotypes of walnut trees by molecular methods are described in this article.

In this study survivability, morphological characteristics and pathogenicity of 12 isolates of Ophiognomonia leptostyla, which is known as causal agent of walnut anthracnose, have been evaluated after 13-years of storage on filter paper in oat meal agar (OMA) and -20°C. The recovery rate varied from 0 to 89 percent and seventy-five percent of stored isolates were shown to be viable. In macroscopic and microscopic studies of revived cultures, the morphology of colonies was uniform for all isolates. Production of asexual bodies (acervular conidiomata) was preserved by all isolates. Fertile perithecia with asci and ascospores were not detected in pure fungal cultures after three months incubation at 8-10°C in darkness. In pathogenicity experiments, there was not a significant variability in infection severity for different isolates, and the first symptoms were observed on leaves 12-16 days after inoculation. Stability of morphological characteristics, ability to sporulation and retaining the pathogenicity of isolates confirmed that transferring of acervuli on filter paper in OMA medium could be a suitable, safe, simple and cost-effective tool to preserve O. leptostyla isolates in a viable state.

Bacterial canker disease is one of the most destructive diseases of walnut trees that causes die back and plant decline and also great damages to quality and quantity of fruits. The disease can be observed in two forms, at depth and the surface of the bark which cause by two bacteria, Brenneria nigrifluens and B. rubrifaciens, respectively. The most important way of the pathogen penetration is the wounds in the trunk and branches which are occurred due to human ‎activities or mechanical harvesting equipment. The disease becomes severe with the deep irrigation and when the nutrition is insufficient and ‎temperature and humidity are high.‎ Current paper explains history, importance, symptoms, biology, host range, sampling and isolation method also differential characteristics of bacteria and methods of disease management.

The effect of different concentrations of mallow (Malva sylvestris) and poppies (Papaver rhoeas) leaves and walnut (Juglanse regia) green husks extracts were investigated on hatching and mortality of second-stage juveniles of Meloidogyne javanica under experimental conditions. In J2 mortality test, the extracts were used in 14 levels of mallow (0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.75, 1, 1.25, 1.5 and 2%), 7 levels of poppy (0.5, 1.5, 2, 2.5, 3, 3.5 and 4%) and 8 levels of walnut green husks (1, 2, 3, 3.5, 4, 4.5, 5 and 6%). In three independent tests, controlling effect of 100 milliliters of the obtained lethal concentrations (LC20, LC50 and LC80) of each extracts (0.36, 0.58 and 0.94% for mallow; 2.3, 2.9 and 3.8% forpoppies; 2.68, 4.07 and 5.18% for walnut green husks) on M. javanica were evaluated under the greenhouse condition. According to the results of this study, the nematicidal effect of all tested extracts against M. javanica was proved under laboratory conditions. In greenhouse trials, any increase in the concentration of plant extracts significantly improved the growth indices of tomato plants and also the obtained LC80of mallow, poppy and walnut green husks extracts significantly reduced the number of galls by 59, 71 and 74%, respectively, and the reproduction factor by 56.7, 85 and 87%, respectively, when compared to the control.

Walnut is one of the most important fruit trees in many parts of the world cultivating. In recent years, walnut aphid Chromaphis juglandicola (Kaltenb) (Hemiptera, Aphididae) is known as a serious pest of Persian walnut (Juglans regia L.) in Iran and other parts of the world. Recently, the damage of the pest increased high on walnut trees in Bavanat region, northern Fars province, Iran. Effect of some pesticides on the pest was studied during growing season of 2014 in Bavanat. An experiment was performed in a Completely Randomized Block Design with treatments including coconut botanical soap (Palizin® SL70%, 2000 ppm), garlic extract (Sirinol® EC80%, 2000 ppm), imidacloprid (Confidor® SC35%, 750ppm) and hexaflumuron (Consult® EC10%, 750ppm) and control with 4 replications. Samplings were conducted before spraying and five times after the spray at 3, 7, 12, 18 and 21 days interval. Based on the results on days of 1, 3, 7, 12, 18 and 21 after spraying, imidacloprid had the highest and coconut oil soap had the lowest effect on walnut aphid. As a result, imidacloprid is the most effective compound to control walnut aphid. However, garlic extract can be recommended as alternative compound with low hazard on environment and human health.

Colorado potato beetle is one of the most important insect pests of potato plants. Frequently and prolonged use of chemical pesticides for controlling this pest, has caused environmental pollution, pest resistance to pesticides and destruction of natural enemies. Some herbal extracts are more degradable and relatively safer than most of the synthetic insecticides and can be used as suitable alternatives in integrated management of Colorado potato beetle. In this study, the effects of leaf extracts of Juglans regia, Sambucus ebulus, Artemisia annua, Satureja sahendica and Salvia sahendica were studied on 2nd instar larvae of Colorado potato beetle, Leptinotarsa decemlineata in laboratory conditions at 26 ± 2 °C, 55±5% RH and a photoperiod of 16:8 (L:D). Potato leaves were treated with 0.625, 1.25, 2.5, 5 and 10% concentrations of the plant extracts using leaf- dipping method. Control leaves were dipped in either methanol or distilled water only. Each treatment consisted of 20 up to 24 h old 2nd instar larvae and had three replicates. Mortality of the larvae was recorded 24, 48, 72 and 96 hours after treatment. The results showed that extracts of Juglans regia, Satureja sahendica and Artemisia annua were more toxic to 2nd instar larvae of the Colorado beetle than Salvia sahendica and Sambucus ebulus. Ninety six hours after treatment, 10% concentration of J. regia, S. sahendica and A. annua caused 93.33, 91.67 and 73.33% mortality and 5% concentration of these extracts caused 58.9, 100 and 48.2% mortality in Colorado potato beetle larvae, respectively. As expected, the mortality decreased with decreasing concentrations. According to the high mortality percent, especially in high concentrations, the extracts of these plants, can be used as potential botanicals for integrated management of Colorado potato beetle.

In recent years, Shallow bark canker (Brenneria nigrifluens) of walnut trees has become fairly widespread in Iran. To determine the distribution of the disease in Damavand, from summer of 2013, bark samples were collected from walnut trees showing symptoms of Shallow bark canker. 46 strains of bacteria were isolated from infected tissues. Strains appeared similar in phenotypic characteristics. On the basis of the morphological and biochemical results and sequencing of RNA polymerase beta sub unit gene the bacterium was identified as Brennerianigrifluens. This is the first report of Shallow bark canker of walnut trees in Damavand.

Kerman province has the highest area under walnut cultivation in Iran. In summer 2014, 422 specimens were collected in walnut orchards of Kerman province, of which 248 specimens (58.8%) were attributed to rodents, 70 (16.6%) were attributed to birds and the remaining 104 specimens (24.6%) were attributed to both rodents and birds. In summer 2015, in those orchards that previously experienced vertebrate damage, five orchards and 27 trees were randomly selected and walnut fruit specimens with signs of rodent and bird damage were collected in four different dates. The damage rate was between 10.5% and 96.2%, giving the average damage rate 34.5%. Analysis of Variance (ANOVA) showed a significant difference of the damage rate among the selected orchards (p0.05).

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.

Leopard moth, Zeuzera pyrina L. (Lep.: Cossidae), is a key pest of walnut in Iran. The efficiency of mating disruption by two commercial products including Isonet® Z and Zeumat Universe® was evaluated in 2011 in East Azerbaijan and Kerman provinces. In each hectar, 300-600 pheromone dispensers for mating disruption were attached to the trees before the emergence of adults. Three pheromone traps were also installed in each plot to evaluate the orientation disruption before the adult's emergence. The pheromone traps did not capture any adult in the plots where mating disruption was performed during the experiment in both provinces while the traps caught the adults in the control plots. This result confirmed the efficiency of the used number of products for orientation disruption of the males. The averages of the number of larval entrances on the branches of plots where mating disruption was conducted by Isonet® Z, Zeumat Universe® and control were respectively 0.18 ± 0.03, 0.13 ± 0.02 and 0.45 ± 0.04 in Kerman province, 0.18 ± 0.03, 0.33 ± 0.04 and 0.63 ± 0.07 in East Azarbaiejan province and 0.18 ± 0.02, 0.2 ± 0.02 and 0.52 ± 0.04 (average ± S. E.) for the pooled data of both regions. There was a significant difference among the averages (P

To study allelopathic effects of iranian walnut (Juglans regia L.) on germination and initial growth of purslane (Portulaca oleracea) and redroot pigweed (Amaranthus retroflexus) an experiment was conducted in shahed university. The result showed that fresh leaf had negatively effected on Radicle Length. Also، with increasing extract concentrations of persian walnut، the seed germination and seedling growth of the two species was reduced significantly.

Planting walnut cultivars resistant to blight caused by Xanthomonas arboricola pv. juglandis is one of the most significant management methods. Considering susceptibility of all walnut green organs to this disease, the aim of this research was to evaluate the relative susceptibility of leaf, unripe and ripe organs of Jamal, Damavand and Z76 local cultivars and Pedro, Serr, Chandler, Franquette and Hartley commercial cultivars to blight in order to establish a suitable evaluation procedure. The causal agent was isolated from blighted fruit samples collected from Qazvin, Zanjan, Orumie and Karaj orchards and after identification, mixture of four isolates was used as inoculum. One-year-old grafted seedlings were evaluated for leaf susceptibility in glasshouse condition. Ripe and unripen fruits were examined in orchard and laboratory, respectively. Based on the result, the resistance of different organs was different in various cultivars. Owing to the lack of any correlation between fruit and leaf susceptibilities, evaluation of both organs in resistance evaluations is necessary.