جستجوی مقالات مرتبط با کلیدواژه "بلوط" در نشریات گروه "گیاهپزشکی"

Oaks (Quercus) are among the most important trees found in forests Iran and rest of the world. Over the last decade, oak charcoal disease (OCD) has become more common in numerous forest areas in the Zagros and Hyrcanian regions, largely due to reduced rainfall and multiple droughts. This disease causes local or systemic necrosis, wilting, and even death of infected oak trees within one or more years. In addition, there is a complex interaction between trees and biotic and abiotic environmental factors. This study was conducted in 2020-2021 on oak trees in seven provinces of the country, namely Khuzestan, Ilam, Lorestan, Kurdistan, Khuzestan, Isfahan and Golestan, to analyze and determine the current status of oak trees in terms of OCD and the causative fungal pathogens. For this purpose, samples of infected oak trees were collected and then the causal agents of the disease isolated and identified morphologically. Detection of the samples was confirmed by sequencing the fungal ITS1-5.8S-ITS2 and ß-tubulin gene. The results showed that the most prevalent fungal pathogens of OCD in the samples were Biscogniauxia mediterranea and Obolarina persica. The prevalence of these fungi in the studied provinces varied, with the highest prevalence of B. mediterranea in Lorestan and the highest prevalence of O. persica in Ilam. The results of this study complemented the existing relatively limited data on the prevalence of each fungal pathogen of OCD in different provinces. In addition, the current status of oak infection in each of the studied regions was clarified.

Scale insects are the important pests of the forest, horticulture and crops, which may weaken plants. Zagros oak forests are one of the most important natural reserves of Kermanshah province that their protection is vital. More than 8,000 species of scale insects have been reported worldwide and 300 species of these insects recorded from Iran. In this research, which was carried out from 2021 to 2022 in Zagros oak forests, Kermes spatulatus specifically feeds on oak trees Quercus spp. is recorded for the first time from Iran. The oak branches and stems which infected with this scale insect were collected from Chalabeh and Dalahu regions in Kermanshah province. After being separated from the branches, the scales were clarified and microscope slides were prepared from them. Then macroscopic and microscopic characteristics of their adult insects and their first-instar nymph were evaluated and described; Adult female of this species shows different colors in two regions; Dalahu samples are black and Challabeh samples are orange in color. But the color of the first nymphal instar are same in the two regions. Also this scale was compared with close scale related species.

Oak thrips, Liothrips pragensis Uzel is found on oak trees in Zagros forests. In this study, population fluctuation and spatial distribution of this species were investigated in oak forests of Javanrud county (Kermanshah province), in 2021. Oak leaves were selected as the sampling unit. Sampling was performed every week from five different areas, so leaves were shaken on a white plastic tray and thrips specimens with a soft brush were transferred into Eppendorf tubes containing 75% alcohol. The results showed that the activity of oak thrips in all five studied areas was occurred on May and their activity and density gradually decreased until it reached its lowest level in September. The highest population density of oak thrips was observed on May with an average of 2.93 ± 0.56, 2.23 ± 0.47, 2.23 ± 0.34, and 0.90 ± 0.28 thrips per sample unit, in Sefid Barg, Bileei, Cheshme Miran and Helanie areas, respectively. However, the highest density was obtained in Hori Abad region in June with an average of 2.06 ± 0.43 thrips per sampling unit. The results of spatial distribution showed that the spatial distribution of oak thrips based on Taylor’s power law and Iwao’s methods was random and aggregated, respectively. Furthermore, based on goodness of fit, the Iwao’s patchiness method was more suitable than the Taylor’s power law method for estimating the spatial distribution of the pest.

Persian oak (Quercus branti Lindl) is the most important forest tree of the Zagros mountains. During the recent drought conditions, the oak decline has widely been observed in the areas of Chaharmahal and Bakhtiari Province, especially the town Lordegan. Symptoms include early fall coloration, early leaf drop, vascular discoloration in the twigs (Fig. A-1), drying of the branches, discoloration of the main trunk and branches, cracks and splitting of the trunk, the presence fungal organs as black and olive powdery under the bark (Fig. B-1) and death of the trees. While up to 70% of the trees may suffer from the disease on south-facing slopes (Fig. D-1), north-facing slopes are normally unaffected(Fig. C-1). In 2018, samples of bark, main trunk, and a branch of trees with symptoms (16 specimens) and some specimens (7 specimens) of apparently healthy trees were collected in Lordegan town and isolated by standard methods of isolation of pathogenic fungi on malt agar and potato-dextrose-agar media. The fungal isolates were purified after growth and sent to Botany Research Department of Iranian Research Institute of Plant Protection for identification. Identification results showed that isolates of Biscogniauxia Mediterranea, Paecilomyces cf variotii and Paraconiothyrium sp. are fungi associated with charcoal rot and oak decay in Chaharmahal va Bakhtiari province. From 16 samples with described symptoms, 9 samples of Paraconiothyrium sp, 5 samples of B. mediterranea and 4 samples of Paecilomyces cf variotii were isolated. Two samples of asymptomatic samples were also isolated Paraconiothyrium sp and B. mediterranea.

Oak dieback is one of the most important diseases that presently affects the Zagros oak forests (Northwest to Southeast of Iran). The presence of Paecilomyces formosus, Biscogniauxia mediterranea and Neoscytalidium novaehollandiae associated with oak trees that show dieback and declining symptoms in the forests of Kermanshah province and the molecular and pathogenic characteristics of these pathogenic isolates were investigated. In molecular analysis using blast search tools, all three pathogens showed homology of 100% with the mentioned species in the GenBank. Pathogenicity test revealed that all isolates of these three pathogens were capable of producing cancers on detached branches and inoculated seedlings of oak trees. Our results showed that all three species obtained from oak trees could produce cankers on excised branches of other trees. In comparison with pathogenicity on two-years-old seedlings under drought stress, there was a significant difference between the three species in terms of the rate of disease progression, so that B. mediterranea caused symptoms on seedlings inoculated under drought stress in a shorter time. P. formosus caused symptoms in longer period on the inoculated seedlings than the other two species. After inoculation, all cankers that extended upward and downward from the point of inoculation were evident on stems of all inoculated seedlings. Re-isolation was performed, and isolates were compared to original cultures providing evidence for fulfilling Koch’s postulates. Investigation of the effect of temperature on radial growth of pathogenic species showed that all three species are thermophilic fungi, which may be related to warming and drought.

Background and Objectives Quercus spp. is the most important and most abundant tree species in west of Iran, especially the Zagros region. The Zagros Mountains have been the original habitat for various Quercus species in Iran. Important pests attack Quercus spp. trees and often cause serious damage. Mites are active arthropod species in oak forests and act as pest, decomposer and predator. Mateials and Methods The bisotunnatural preserved area in Kermanshah province is located in height of 1320 meters above sea level. To investigate the fauna of Prostigmatic mites associated with Quercus spp. in bisotunnatural preserved area, samples were taken from different parts of location in 2018 -2019 from the soil and aerial parts of the Quercus spp. forest trees. Specimens were transferred to the laboratory, separated using berlese funnel, clarified in lactic acid and mounted in Hoyer’s liquid. Results In this study in total 12 species and 16 genera belonging to 12 families were identified. The most abundant species was Molothrognathus mehrnejadi (Liang and Zhang, 1997), from Caligonellidae. Identified species are as follows: Anystidae: Anystis baccarum Linnaeus, 1758; Bdellidae: Cyta coerulipes (Duges, 1834); Cunaxidae: Pulaeus glebulentus Den Heyer, 1980; Tydeidae: Lorryia woolleyi (Baker, 1968), Tydeus caudatus (Duges, 1834) sensu Baker, 1970; Ereynetidae: Ereynetoides amplectorus Hunter, 1964; Iolinidae: Pronematus ubiquitus (McGregor, 1932), Pronematus rykei Meyer & Rodrigues, 1966; Erythraeidae: Parerythraeus sp., Abrolophus sp.; Smarididae: Smaris sp., Fessonia sp.; Raphignathidae: Raphignathus sp.; Tetranychidae: Tetranychus urticae Koch, 1836; Tetranychus turkestani (Ugarov and Nikolski), 1937, Eotetranychus frosti (McGregor, 1952); Trombididae:Allothrombium sp.; Cheyletidae: Acaropsellina sollers Kuzin, 1940. Discussion In this study, the collected species Anystis baccarum Linnaeus, 1758, was previously reported by Yazdanpanah and Ostovan (2014) in the oak forests of the Fars Province. The collected species Cyta coerulipes, Smaris sp. and Fessonia sp. were previously reported by Farahmandi (2015) from the oak forests of Yasuj. In addition, Tetranychus urticae, collected in this study, was previously reported by Niyazi (2017) on oak trees in Ilam province and Amini et al. (2016) from oak in Marivan city. In this study nine species and four genera were collected and reported, which have not been reported previously from oak which include:   Pulaeus glebulentus Den Heyer, 1980, Lorryia woolleyi (Baker, 1968), Tydeus caudatus (Duges, 1834), Ereynetoides amplectorus Hunter, 1964, Pronematus ubiquitus (McGregor, 1932, Pronematus rykei Meyer & Rodrigues, 1966, Tetranychus turkestani (Ugarov and Nikolski), 1937, Eotetranychus frosti (McGregor, 1952), Acaropsellina sollers  Kuzin, 194,Parerythraeus sp, Abrolophus sp, Raphignatus sp. and Allothrombium sp. A Checklist of reported prostigmatic mites from oak forests of Iran is provided as well. This list included 74 species belonging to 10 genera and 17 families.

The use of colored sticky traps is very common in population monitoring and pest management. The color trap attractiveness and capture rates of thrips vary according to species and trap color. Different color preferences of many thrips species have been studied by numerous scientists to enhance the attractiveness and sensitivity of various traps. In this study, the attraction of thrips by colored traps (blue, yellow and white) in the oak forests of Khoran and Kalan regions located in Eyvan city (Ilam Province, west of Iran) was investigated in 2018. The results showed that in both Khoran and Kalan regions, in all sampling months (except December), the blue sticky traps attracted significantly more thrips than other sticky traps. In the Khoran region, the highest number of attracted thrips with a value of 19.80 ±1.35 was related to blue traps and the May, and the lowest number of attracted thrips with a value of 1.01±0.44 was related to white and August. In addition, in the Kalan region, the highest and lowest number of thrips with a value of 15.80±1.35 and 1.80±0.3 were related to blue and yellow sticky traps in May and December, respectively. Generally, the results of this study showed that the efficiency of blue sticky traps was more than yellow and white traps. Overall, the use of blue sticky traps is appropriate for monitoring thrips on oak trees in the spring season.

Oak charcoal rot is caused by two fungi, Biscogniauxia mediterranea and Obolarina persica. These fungi, which are opportunistic or secondary invaders and attack stressful trees, are one of the main problems of oak forests in Iran. The disease was first reported in 2011 in the northern forests on Quercus castaneifolia and Zelkova carpinifolia trees and then in the Zagros forests on Q. brantii tree. The disease has spread rapidly in the forests of the Zagros over the years. Symptoms of the disease include decay and death of trees, browning of leaves and early fall. Gum secretion on the branches and trunks of old trees and browning of wood texture and woody vessels can be seen up and down the height of the trunk. The morphological characteristics of pathogens, the spread and survival of pathogens, and disease management methods are described in this article.

Zagros Mountains in the west of Iran and some areas in the north of Iran are covered by oak trees. Four important diseases of Iranian oak trees are charcoal rot, chestnut blight, sudden death and powdery mildew. The symptoms of these diseases and the characteristics of pathogens as well as their prevalence are described in this article. Some strategies for protecting the oak trees from these diseases are also proposed here.

The oak leaf roller moth (Tortrix viridana L.) is one of the most important oak pests in Iran. In order to investigate fluctation changes of this pest, weekly samplings of its different life stages were done in West-Azerbayjan. The number of larval instars were determined by growing and measuring the head capsula width of 1000 larvae at different ages. The effect of host plant on weight changes of final instar larvae and pupae on three oak species of Quercus infectoria, Q. brantii and Q. libani was studied. Populational changes of adult insects were investigated using 10 triangle pheromone traps. Five larval instars were determined for this pest. Neonate larvae of the pest start their activities from late March in Mirabad and from early April in Paradanan. The formed larvae and pupae on gall oak (Q. infectoria) weigh more than there growing on two other oak species. Adult insects were first captured on May 23 in Mirabad (6.2 insects in each trap). The highest degree of pest capture was also recorded at the peak
time of pest population with the average of 132 insects in each trap in Mirabad which indicates that this area is highly infected with the pest. The oak leaf roller moths stopped their activity in mid-July in all of the studied areas.

The induced galls by oak gall wasps were collected from various oak forests of Iranian province of West Azerbaijan in the regions of Ghabre-Hossein، Mir-Abad، Vavan، Shalmash، Rabat and Dar-Ghabr during from April to November 2009. The optimum number of samples was found to be 40 oak trees. In each tree، as a sampling unit، all of the existing galls were counted. The species richness of oak gall wasps in the West Azerbaijan province was measured and the parameters such as Simpson’s، Shannon’s H''، and Sorensen similarity indexes were calculated. In this study، 35 species of oak gall wasps on the oak tree species of Quercus infectoria، Q. brantii and Q. libani were identified. Most galls were observed on Q. infectoria. All of the collected oak gall wasp species belonged to the genera Andricus Hartig، Cynips L.، Neuroterus Hartig، Biorhiza Westwood، Pseudoneuroterus Kinsey، Chilaspis Mayr and Aphelonyx Mayre. The genus Andricus included 23 species of oak gall wasps. The highest Simpson and Shannon indexes were recorded for the spring galls of Mir-Abad and for the fall galls of Ghabre-Hossein and Dar-Ghabr regions. The Sorensen similarity index reached its peak for the spring galls (sexual generation of oak gall wasps) of Ghabre-Hossein and Mir-Abad and for the fall galls (asexual generation of oak gall wasps) of Ghabre-Hossein and Dar-Ghabr. The distribution of oak species and subspecies، and geographical and climatic aspects are believed to be among the key factors for the species diversity of oak gall wasps.

Forests cover about 5,200,000 hectares of the west of Iran, from which 500,000 hectares are located in Kurdistan province. One of the most important pests in the oak forests of this province is oak leaf roller moth, Tortrix viridana L. (Lep.: Tortricidae). This pest significantly damages the oak forest each year. Using pheromone trap is one of the suitable methods for monitoring of this pest. In this work, distribution and flight period of the pest were studied by pheromone traps during two years. Fifteen regions were trapped at the equal distances (40 km) from Kamyaran (south west of Kurdistan province) to Baneh (north west of Kurdistan province) to investigate the presence and distribution of this moth. Also, a region located between Sanandaj and Marivan was selected to study the flight period. Some traps were established in this region and checked every two days. Investigation of pest distribution showed that oak leaf roller moth was present all over the sites from Kamyaran to Baneh. Different populations of moth were trapped in all over the sites. The highest population was trapped in Colit region (mid-west of Kurdistan province). The study of flight period showed that first moths were trapped on May, 16th and the peak of the flight took place on May, 21st and finally the last moths were trapped on June, 24th. Therefore, adults activated during 40 days; mating and oviposition occurred during this period. Incubation period lasted 9 months and activation of larvae was coincident with flashing of foliar buds.