Trees In Iran Research Articles

A revision of the family Cucurbitariaceae with additional new taxa from forest trees in Iran

A revision of the family Cucurbitariaceae with additional new taxa from forest trees in Iran

First Report of Diplodia intermedia Causing Canker and Dieback Diseases on Apple Trees in Canada.

A dieback of apple trees (Malus domestica (Suckow) Borkh.) associated with cankers was observed in commercial orchards in southwestern Ontario, Canada, in 2019. Fifteen 2 to 10-year-old symptomatic trees were collected from three orchards exhibiting up to 37% disease incidence. Small sections of diseased wood (1 cm long) were surface sterilized with 70% ethanol for 30 sec and 1% NaClO for 20 min, rinsed thrice in sterile water, placed on 2% PDA (Difco) amended with kanamycin (50 mg liter-1), and incubated at 22°C for 5 days in the dark (Ilyukhin et al. 2023). Fungal colonies that were consistently isolated were hyphal-tipped, transferred to individual PDA plates and incubated at 22°C for 7 days in the dark. Purified isolates with same characteristics were classed into morphotypes. One morphotype was initially white and turned dark olivaceous with dense aerial mycelium. Pycnidia were produced on pine needles on PDA (Fig. S2) after incubation at 22°C for 17 days in the dark. Conidia were brown, aseptate, ovoid, and measured 27.9 to 31.3 μm x 12.1 to 14.2 μm (mean ± S.D. of 15 conidia = 29.9 ± 0.9 μm × 13.2 ± 0.6 μm), the typical morphology of a Diplodia sp. (Phillips et al. 2012). Genomic DNA was extracted from a 7-day-old culture of a representative isolate M45-28, using the Plant/Fungi DNA Isolation Kit (Norgen Biotech, Canada). The internal transcribed spacer (ITS), translation elongation factor 1-α (EF1-α) and β-tubulin gene regions were amplified and sequenced with primers ITS1/ITS4, EF1-728F/EF1-986R and Bt2a/Bt2b and deposited in GenBank with accession numbers MZ970605, MZ995430 and MZ995431, respectively. Based on the sequence, the fungus was identified as Diplodia intermedia A.J.L. Phillips et al. and matched isolates from different hosts and countries (ITS: 100%, MG220378; EF1-α: 100%, MG220385; β-tubulin: 99.24%, MT592502). The maximum likelihood-based phylogenetic analysis of ITS, EF1-α and β-tubulin concatenated sequences was performed using IQ-Tree 2.2.2.7 (Minh et al. 2020). M45-28 was clustered with high bootstrap support values with D. intermedia isolates from the Westerdijk Fungal Biodiversity Institute collection, including the ex-holotype (CBS 124462) (Fig. S1). A living culture of M45-28 was deposited in the Canadian Collection of Fungal Cultures (DAOMC 252253). Pathogenicity assay was conducted by inoculating mycelial plugs from a 7-day-old culture of M45-28 into wounds made on the trunk of 5 eight-month-old potted healthy 'Royal Gala' apple seedlings. Five control seedlings were inoculated with sterile plugs. Canker symptoms appeared 15 days after inoculation, spread around, up and down the main stem from the inoculation point, and by 7 weeks the upper portion of the seedling was dead (Fig. S2). Diplodia intermedia was re-isolated from all inoculated seedlings and species identity was confirmed by sequencing as described above, fulfilling Koch's postulates. Control seedlings remained symptomless and the fungus was not isolated from the wood. Diplodia intermedia was reported to cause cankers on apple in Uruguay (Delgado-Cerrone et al. 2016), wild apple (Malus sylvestris) in Portugal (Phillips et al. 2012), grapevines in France (Comont et al. 2016) and forest trees in Iran (Kazemzadeh Chakusary et al. 2019). To the best of our knowledge, this is the first report of D. intermedia causing canker and dieback diseases on apple trees in Canada. Further studies are required to better understand the epidemiology involved in the dynamic spread of the disease in order to recommend an adequate phytosanitary program for its control.

First report of Melampsora ferrinii (pucciniales) on Babylon willow (Salix babylonica) in Iran

As an agroforestry resource willow species (Salix spp.) becoming increasingly important in the protection of riverbanks, recovery of floodable lands, soil bioremediation, biomass production, and wicker furniture manufacture, Babylon willow (Salix babylonica) is widely planted all over the world and is found throughout Iran as part of the rural landscape and is mostly planted for ornamental or bioremediation purposes. Rust fungi in the genus Melampsora usually cause disease on Salix species. Identification of Melampsora species is often complicated because there are few differences in spore morphology and little publicly available comparative sequence data. Willow trees in Iran have been reported to be infected by 15 Melampsora species; however, most of these records are based on morphological characterization. During surveillance activities carried out in June 2007, a rust species was detected on isolated Babylon willow trees in an area in Northern Iran. Both the rust fungus and the host plant were identified on the basis of morphological features and DNA sequencing. Based on a combination of morphology, large subunit (LSU) rDNA sequencing and phylogenetic analyses, our rust specimen was identified as Melampsora ferrinii, which is newly reported from Iran on Salix babylonica. Melampsora ferrinii was originally described from the Americas and this is the first time this rust has been observed on its telial host, Babylon willow, in Asia. The documentation of the rust fungus was performed using both scanning electron microscopy (SEM) and light microscopy. Additionally, an identification key for Melampsora species reported on Salix spp. in Iran is included.

First Report of Cytospora azerbaijanica Causing Cytospora Canker and Shoot Dieback on Peach (Prunus persica) in California, U.S.A.

Peaches (Prunus persica L.) are an important crop in the United States with California leading the nation in peach production, with approximately 505,000 tons valued at $378.3 million (USDA National Agricultural Statistics Service, 2021, https://www.nass.usda.gov/). From April to July 2022, symptoms of branch and scaffold canker as well as shoot dieback were observed in three peach (cvs. Loadel, Late Ross and Starn) orchards located in San Joaquin County, California. Samples were collected from about 12 trees for each cultivar. Fast-growing, white, flat colonies were consistently isolated from active cankers on acidified potato dextrose agar (APDA) following the method described by (Lawrence et al. 2017). Pure fungal cultures were obtained by transferring single hyphal tips onto new APDA Petri plates. A total of 22 isolates were obtained. Each fungal isolate was recovered from a single diseased branch (40 to 55% recovery). All isolates in this study shared similar morphological characteristics. Fungal colonies were fast-growing with relatively even but slightly dentate margin, flat with white to off-white mycelium that turned vinaceous buff to pale greyish sepia (Rayner 1970) with age. Black, globose, ostiolated pycnidia, 0.8-(1.3)-2.2 mm diameter, with brownish surface hyphae formed on peach wood embedded in PDA after approximately three weeks and exudated buff-colored mucilage. Pycnidia were both solitary and aggregated and had multiple internal locules sharing invaginated walls. Conidiogenous cells were hyaline, smooth-walled, septate, tapering towards the apex, 13-(18.2)-25.1 × 0.8-(1.3)-1.9 µm (n = 40). Conidia were hyaline, allantoid, smooth, aseptate, 5.5-(6.3)-7.1 × 1.4-(1.9)-2.3 µm (n = 40). Genomic DNA was extracted and sequences of the internal transcribed spacer region (ITS) using ITS5/ITS4 universal primers, translation elongation factor 1α gene (TEF) using primers EF1-728F/EF1-986R, second largest subunit of RNA polymerase II (RPB2) using primers RPB2-5F2/fRPB2-7cR, and actin gene region (ACT) using primers ACT-512F/ACT-783R were obtained and compared with sequences available in GenBank (Lawrence et al. 2018; Hanifeh et al. 2022). Isolates were identified as Cytospora azerbaijanica following DNA sequencing and morphological identification. Consensus sequences of the four genes of two representative isolates (SJC-66 and SJC-69) were deposited into GenBank database (ITS: OQ060581 and OQ060582; ACT: OQ082292, OQ082295; TEF: OQ082290 and OQ082293; RPB2: OQ082291 and OQ082294). The Basic Local Alignment Search Tool (BLAST) indicated that the sequenced RPB2 genes of isolates (SJC-66 and SJC-69) were at least 99% identical to that of Cytospora sp. strain shd47 (Accession: MW824360) covering at least 85% of the sequences. The actin genes from our isolates were at least 97.85% identical to that of Cytospora sp. strain shd47 (Accession: MZ014513), covering 100% of the sequences. The translation elongation factor gene from isolates (SJC-66 and SJC-69) was at least 96.4% identical to that of Cytospora sp. strain shd166 (Accession: OM372512), covering 100% of the query. Those top hit strains belong to C. azerbaijanica, recently reported by Hanifeh et al. (2022). Pathogenicity tests were performed by inoculating eight wounded, 2- to 3-year-old healthy branches on each of eight 7-year-old peach trees, cvs. Loadel, Late Ross and Starn, using 5-mm-diameter mycelium plugs collected from the margin of an actively growing fungal colony on APDA. Controls were mock-inoculated with sterile agar plugs. Inoculation sites were covered with petroleum jelly and wrapped with Parafilm to keep moisture. The experiment was performed twice. After four months, inoculation tests resulted in vascular discoloration (canker) above and below the inoculation sites (average necrosis length of 114.1 mm). Cytospora azerbaijanica was re-isolated from all infected branches (70 to 100% recovery) completing Koch's postulates. Controls remained symptomless and no fungi were isolated from the slightly discolored tissue. Cytospora species are destructive canker and dieback pathogens of numerous woody hosts worldwide. Recently, C. azerbaijanica was reported in causing canker disease of apple trees in Iran (Hanifeh et al. 2022). To our knowledge, this is the first report of C. azerbaijanica causing canker and shoot dieback of peach trees in the United States and worldwide. These findings will aid towards a better understanding of genetic diversity and host range of C. azerbaijanica.

Morphology of the last instar larva and pupa of Paranthrene diaphana (Dalla Torre & Strand 1925) (Lepidoptera: Sesiidae), a serious pest of the babylon weeping willow trees in Iran.

This work presents the first description of the morphology of the last larval instar and pupa of the clearwing moth species Paranthrene diaphana (Dalla Torre & Strand, 1925). All diagnostic morphological features are described in detail, compared with the closely related species Paranthrene tabaniformis (Rottemburg, 1775) and P. insolitus Le Cerf 1914, and the features are illustrated with photographs and line drawings. The research on clearwing moths in Tehran Province (central Iran) has revealed that P. diaphana is a serious new pest that causes significant damage to babylon weeping willow trees Salix babylonica L. (Salicaceae).

Mycelial and sexual compatibility in plant pathogen, Leucostoma cinctum

The canker disease caused by Leucostoma cinctum is one of the most destructive diseases in fruit trees in Iran. For investigation of mycelial/sexual compatibility in L. cinctum, 64 isolates from 10 different plants, and 11 provinces of Iran were used. Isolates were crossed in all possible combinations on PDA at 25 °C for mycelial compatibility, and 14 multi-merge MCGs were identified among the isolates, revealing the average genetic diversity. In vitro sexual reproduction of the fungus was assessed using 14 ascospore progeny of two different perithecia, and the isolates were crossed in all possible pairwise combinations on culture media amended by different sterilized twigs. In four crosses on oatmeal agar with 2.5% sucrose, and apricot twigs, fertile perithecia were formed after 5 months, confirming heterothallic nature of the L. cinctum. Also, this is the first report of the in vitro viable sexual reproduction of the L. cinctum in the world.

Morphological and molecular identification of plant pathogenic fungi associated with necrotic wood tissues of pomegranate trees in Iran

Morphological and molecular identification of plant pathogenic fungi associated with necrotic wood tissues of pomegranate trees in Iran

Revision of the Microsphaeropsis Complex with Addition of Four New Paramicrosphaeropsis L.W.Hou, L.Cai & Crous Species from Zagrosian Forest Trees in Iran

Révision du complexe Microsphaeropsis avec l'ajout de quatre nouvelles espèces de Paramicrosphaeropsis L.W.Hou, L.Cai & Crous provenant d'arbres de la forêt zagrosienne en Iran. Paramicrosphaeropsis L.W.Hou, L.Cai & Crous est un taxon monophylétique de la famille des Didymellaceae et comprend, à ce jour, deux espèces. Lors d'une étude sur les champignons de type Microsphaeropsis associés aux arbres de la forêt zagrosienne en Iran, quatre nouvelles espèces de Paramicrosphaeropsis ont été identifiées et décrites, dont P. amygdalus M.Mehrabi-Koushki, S.Artand, K.D.Hyde & Jayaward., sp. nov. d'Amygdalus scoparia Spach., P. pistacicola M.Mehrabi-Koushki, S.Artand, K.D.Hyde & Jayaward., sp. nov. de Pistacia spp., P. salandica M.Mehrabi-Koushki, S.Artand, K.D.Hyde & Jayaward., sp. nov. de Crataegus sp., Nerium oleander L., Quercus brantii Lindl. et Ziziphus sp., et P. zagrosensis M.Mehrabi-Koushki, S.Artand, K.D.Hyde & Jayaward., sp. nov. de Crataegus sp. et Quercus brantii. Des analyses phylogénétiques basées sur une combinaison de quatre régions génomiques, incluant l'ADN ribosomal 28S nucléaire partiel (LSU), les régions intercalaires transcrites internes 1 et 2 comprenant l'ADN ribosomal nucléaire 5.8S intermédiaire (ITS), la β-tubuline partielle (tub2) et la deuxième plus grande sous-unité de l'ARN polymérase II (rpb2), sont fournies pour clarifier les affinités entre nouvelles espèces et autres taxons du complexe Microsphaeropsis. En outre, un nouveau genre Heteromicrosphaeropsis M.Mehrabi-Koushki, K.D.Hyde & Jayaward., gen. nov. et cinq nouvelles combinaisons sont introduits. Les nouvelles combinaisons sont Heteromicrosphaeropsis ononidicola (Thambug., Camporesi & K.D.Hyde) M.Mehrabi-Koushki, K.D.Hyde & Jayaward., comb. nov., Microsphaeropsis cytisi (W.J.Li & K.D.Hyde) M.Mehrabi-Koushki, K.D.Hyde & Jayaward., comb. nov., M. cytisicola (Wanas., Camporesi, E.B.G.Jones & K.D.Hyde) M.Mehrabi-Koushki, K.D.Hyde & Jayaward., comb. nov., M. cytisinus (Tennakoon, Camporesi & K.D.Hyde) M.Mehrabi-Koushki, K.D.Hyde & Jayaward., comb. nov. et M. minima (W.J.Li & K.D.Hyde) M.Mehrabi-Koushki, K.D.Hyde & Jayaward., comb. nov.

Reassessment of the occurrence and distribution of Xanthomonas arboricola on fruit trees in Iran

AbstractBacterial canker and spot of stone fruits and bacterial blight of walnut, caused by different pathovars of Xanthomonas arboricola, namely X. arboricola pv. pruni and X. arboricola pv. juglandis, respectively, are considered among quarantine or regulated (nonquarantine) agents in different countries. The two pathogens were initially reported in Iran in 2005 and 1977, respectively. However, the precise identity, pathogenicity status and geographic distribution of these pathogens have been questioned. In this study, we have employed a series of comprehensive field surveys and samplings over a course of 5 years (2015–2019) across 16 provinces to reassess and clarify the occurrence and distribution of X. arboricola on fruit and nut trees in Iran. Besides dozens of non‐Xanthomonas and nonpathogenic bacterial strains, 27 X. arboricola strains were isolated from stone fruits (n = 13) and walnut (n = 14). Except for the strains Peh35, Peh78 and Peh79, the stone fruit strains were nonpathogenic on their host of isolation as well as several other plant species, while the walnut strains were pathogenic on their host of isolation. Multilocus sequence analysis (MLSA) of four housekeeping genes, atpD, dnaK, gyrB and rpoD, revealed that among the stone fruit strains only Peh78 and Peh79 could be assigned into X. arboricola pv. pruni, while the walnut strains were identified as X. arboricola pv. juglandis. Based on the results of pathogenicity assays and phylogenetic analyses, we confirm the occurrence of X. arboricola pv. juglandis in Iran, while X. arboricola pv. pruni was absent in the plant samples evaluated in this study.

Multigene phylogeny, morphology, and pathogenicity trials reveal novel Cytospora species involved in perennial canker disease of apple trees in Iran

In recent years, canker and die-back diseases have become a growing threat for the productivity and longevity of apple orchards in Iran. In this study, 131 Cytospora isolates were recovered from symptomatic tissues of apple trees in apple orchards of Iran. Multigene phylogenetic inference based on combined sequence data of ITS, act, rpb2, and tef1-α loci, supplemented with morphological characteristics and pathogenicity assay revealed four novel Cytospora species which were described as C. avicennae, C. azerbaijanica, C. ershadii, and C. iranica, and four known species, namely C. chrysosperma, C. parasitica, C. paratranslucens, and C. sorbicola. Also, C. sorbicola is newly reported on apple trees worldwide. Koch's postulates were fulfilled to confirm that all eight species in this study were pathogenic on apple trees in Iran, among which C. sorbicola was the most intensive species. The results of this study further highlight rich diversity among Cytospora species occurring on apple trees, revealing several novel Cytospora species on this host. The host range, geographical distribution, and economic significance of novel species on apple industry remains to be studied.

Neoscytalidium novaehollandiae causes dieback on Pinus eldarica and its potential for infection of urban forest trees

Neoscytalidium novaehollandiae is one of the most important pathogens on woody plants which has increasingly been reported as a pathogen in different hosts in recent years. The pine trees are widely cultured in many cities of Iran. In recent years, dieback symptoms were observed on Pinus eldarica trees in Tehran and Qazvin provinces. The aim of this study was to investigate the dieback causal agent on P. eldarica trees in Iran. The branches and cones of P. eldarica trees were sampled for fungal isolation. The morphological and molecular characterizations (ITS, LSU, and TEF1-α regions) identified N. novaehollandiae as a dieback causal agent. This is the first report of N. novaehollandiae disease of P. eldarica trees in Iran. Furthermore, disease severity was assayed on 19 urban forest trees under three different temperature and relative humidity (RHs) regimes. C regime (29 °C and 15% RH) displayed more disease severity on detached branches than B (24 °C and 80% RH) and A (19 °C and 35% RH) ones. This study presents the host range of this pathogen, and showed that these potential hosts are prone to this pathogen under high temperature and low humidity which urban forest trees experienced in recent decades.

The Occurrence of Stereum hirsutum Associated with Wood Rotting of Olive Trees in Iran

Abstract In summer 2021 (June–July), disease symptoms on trunks and shoots were observed in olive groves in the Tarom Sofla region, Qazvin province, Iran. The symptoms were light-pink discoloration and surface depression in the external layers of the wood. As the disease progressed, brown streaks of tissue appeared on the longitudinal sections of the wood. The identification of fungus was made based on PCR amplification of the rDNA-ITS region with the universal fungal primers ITS5 and ITS4. BLAST searches revealed 99.52% identity to Stereum hirsutum. Several species of basidiomycetes are known to live on wood as saprobionts or parasites. On olive trees, they cause white rot symptoms. Although they are not directly responsible for tree mortality; however, they can lead to structural deterioration of woody tissues. To the best of our knowledge, this is the first report of S. hirsutum associated with wood rotting of olive trees in the world.

New report of Biscogniauxia rosacearum as a pathogen on almond trees in Iran

Biscogniauxia species are known as fungal trunk pathogens on various tree species in the world. During a survey of trunk diseases of fruit trees conducted in Iran, a branch dieback was observed on almond trees in Kerman province (in the Southeast of Iran). Evaluation of symptomatic branches revealed wood discoloration in cross-sections and the presence of fruiting bodies of an ascomycete fungus on their bark. A total of 31 fungal isolates were obtained, 13 isolates recovered from necrotic wood tissues and 18 isolates from fruiting bodies. These isolates were subjected to morphological analysis as well as sequencing analysis of the partial ITS-rDNA and beta tubulin gene sequences. These fungal isolates were identified as Biscogniauxia rosacearum. Results of the pathogenicity tests showed that this species is pathogenic on almond shoots. Based on our knowledge, this is the first report of this species on almond trees in Iran and in the world.

First Report of Meloidogyne incognita on Mulberry in Saudi Arabia.

The genus Morus comprises many species (Suttie 2012). The species Morus alba is one of the most popular mulberry species worldwide. In October 2020, numerous mulberry trees presented chlorotic leaves and stunted growth with severe root galling in a private compound in Riyadh region, Saudi Arabia. The infected roots showed galls, which are typical symptoms of infection by root-knot nematodes (RKNs). Infected roots were dissected, and males and females were extracted from roots while second stage juveniles (J2s) were from both soil and eggmasses. Morphological and morphometrical features were documented. Perineal patterns of females, males, and J2s were studied using a compound microscope. The endoparasitic females had pearly shaped bodies with projecting neck. Stylet knobs were rounded and set off and the shape of the cone distinctly curved. The posterior perineal had a dorsally high square arch. Striae patterns were zig-zag or forked along the lateral lines. Males were vermiform and the head cap flat to concave. Mostly conus of stylet was longer than shaft. Stylet knobs were prominent, set off, flat and usually greater width than the length. Males had a bluntly rounded tail, spicules were slightly curved and gubernaculum was crescentic. The J2s were vermiform, and stylet knobs were prominent and rounded shape. The J2s tail had a transparent area with an obtuse tip. The morphological measurements (means and range) of the perineal patterns of females (n = 4) were: length of vulval slit (LVS) = 22.5 (21.5 to 23.4) μm, anus to vulval slit (AVS) = 22 (21.8 to 22.1) μm, and anus length (AL) = 7.7 (7.5 to 7.8) μm. The males (n = 16) measurements were: length (L) = 1136 (1116 to 1159) μm; a (total body length / greatest body width) = 34.8 (33 to 37.1); body width = 32.7 (31.2 to 33.8) μm; stylet length = 25.6 (24.7 to 27.3) μm; dorsal oesophageal gland orifice (DGO) = 2.9 (2.6 to 3) μm, tail length = 7.1 (6.5 to 7.8) μm, c (total body length / tail length) = 161 (143.1 to 175), spicules length = 30.8 (26 to 33.8) μm; gubernaculum = 9.7 (9.1 to 10.4) μm. The J2s (n = 11) measurements were: L = 395 (378 to 405) μm; a = 26.2 (24.3 to 28.4); c = 8.6 (8.2 to 9.2); head end to metacorpus valve = 53 (49.4 to 54.6) μm; excretory pore to head end = 78 (72.8 to 80) μm, stylet length = 10.7 (10.4 to 11.7) μm; body width = 15.1 (14.3 to 15.6) μm; tail length = 45.8 (44.2 to 49.4) μm; hyaline tail terminus length = 12.5 (10.4 to 13) μm. Both the morphological and morphometrical features of the perineal pattern of the females, males, and J2s match the original description of Meloidogyne incognita (Kofoid and White, 1919) Chitwood, 1949 (Eisenback and Hirschmann 1981; Taylor and Netscher 1974). To perform Koch's postulates, mulberry plants maintained in pots were inoculated with 2,500 J2s and eggs of the original population of M. incognita using five replicates. After two months, all inoculated plants had galled roots typical of RKNs. Reproduction factor value was 6.4. The noninoculated plants did not present galls in the roots. These results confirmed the nematode's pathogenicity on mulberry. To the best of our knowledge, this is the first report that M. incognita was identified as a parasite of mulberry (Morus alba) in Saudi Arabia and the world, while Meloidogyne hispanica was reported on mulberry trees in Iran (Shokoohi et al. 2016). The importance of this report shed some lights on this new problem to direct the attention of farmers and home gardeners to take actions for the management of this newly identified problem. The authors declare no conflict of interest. Acknowledgments Authors wish to thanks College of Food and Agricultural Sciences, Research Center and Deanship of Scientific Research, King Saud University, Saudi Arabia for supporting this work.

Phytotoxins Produced by Two Biscogniauxia rosacearum Strains, Causal Agents of Grapevine Trunk Diseases, and Charcoal Canker of Oak Trees in Iran.

Biscogniauxia rosacearum, recognized for the first time as a pathogen involved in grapevine trunk diseases in Paveh (west of Iran) vineyards, produced meso-2,3-butanediol (1) as the only phytotoxin. Nectriapyrone (2), (3R)-5-methylmellein (3), (3R)-5-methyl-6-methoxymellein (4), and tyrosol (5) were instead produced as phytotoxins from a strain of the same fungus isolated from oak trees in Zagros forests of Gilan-e Gharb, Kermanshah Province. They were identified comparing their 1H and 13C NMR, ESIMS, and specific optical rotation data with those already reported in the literature. The phytotoxicity of metabolites (1–5) was estimated by leaf puncture assay on Quercus ilex L. and Hedera helix L., and by leaf absorption assay on grapevine (Vitis vinifera L.) at a concentration of 5 × 10−3 and 10−3 M. Tested on grapevine, meso-2,3-butanediol (1) and (3R)-5-methyl-6-methoxymellein (4) resulted to be the most phytotoxic compounds. On Q. ilex, nectriapyrone (2) and tyrosol (5) showed severe necrosis at the highest concentration while none of the compounds (1–5) was active on H. helix. Furthermore, the phytotoxicity of compounds 3 and 4 was also compared with that of some related natural melleins to perform a structure-activity relationship (SAR) study. The results of this study were also discussed.

Identification and Characterization of Bacterial Agents Causing Moderate Damage and Souring of the Fig Fruits

In order to determine the factors of decay and sourness of fig fruits, in the summer of 2016-17, 60 leaf, fruit and stem samples from different regions of Tehran, Varamin (Qal'e No), Mazandaran (Amol, Noor and Sari), Lorestan from Iran and a branch of fig fruit sample from Italy were collected. We obtained 30 isolates from the sample. The pathogenicity of 30 isolates were confirmed by artificially inoculation using fig fruits. They were also characterized based on key phenotypic traits. All 30 isolates showed hypersensitivity reaction to tobacco, pelargonium and did not show pathogenicity to potato tubers. 16S rRNA gene of the 10 representative isolates were sequenced. Ten isolates were identified as Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Pseudomonas fulva, Brevibacterium linens, Pseudomonas fragi, Bacillus licheniformis, Bacillus paralicheniformis and Bacillus cereus based on the determined sequences. None of the isolates caused fruit rot but typical disease symptoms were observed on fig leaves and fruits. This is the first report of the presence of pathogenic bacteria on fig trees in Iran.

Growth and Nutrients Uptake in Commercial Pear Cultivars on Seedling, Pyrodwarf® and OH × F69 Rootstocks

Pyrodwarf and OH × F69 rootstocks are the main clonal rootstocks for pear trees in Iran. This research was conducted to compare growth and nutrient uptake in different commercial pear cultivars including; Louise Bonne, Dargazi and William`s Duchesse on Pyrodwarf, OH × F69 and Dargazi seedling rootstocks in two years in the nursery. Both clonal rootstocks inducted higher growth in cultivars. Cultivar Louise Bonne had the highest growth on Pyrodwarf rootstock. Calcium content varied from 1.4% to 1.5%, but nitrogen, phosphorus, potassium and manganese showed higher variation, and the highest content of these nutrients were observed in cultivar Dargazi on Pyrodwarf rootstock. The lowest and the highest variations were observed in zinc and iron content, respectively. In addition, about 30% of total iron of the leaves was active iron, indicating high level of active iron in pear in comparison with other fruit tree species. In all graft combinations, variation in micro and macro nutrients contents were in optimum range. Comparison of nutrient contents with active lime level in soil indicated that the range of 10-15% active lime in soil would not hinder growth and nutrients uptake of plants.

Bacterial diseases of walnut trees in Iran

Bacterial diseases of walnut trees in Iran

Comparative infectivity and biocontrol potential of Acrobeloides k29 and entomopathogenic nematodes on the leopard moth borer, Zeuzera pyrina

The leopard moth, Zeuzera pyrina L. (Lepidoptera: Cossidae) is a serious pest of walnut trees in Iran. Due to special habitat of this cossid, the application of entomopathogenic nematodes (EPNs) may offer an efficient strategy in suppressing populations of this pest. The efficacy of two commercially available EPNs Steinernema carpocapsae and Heterorhabditis bacteriophora, as well as a local insect-killing nematode (Acrobeloides K29) were investigated against Z. pyrina larvae in laboratory, semi-field, and field conditions. Laboratory experiments included pathogenicity assessment of aforementioned nematodes in plates using a range of concentrations [5, 10, 20, 50 and 100 infective juveniles (IJs) per larva], as well as evaluation of their reproduction potential on Z. pyrina larvae with concentrations of 5 and 20 IJs per larva. Application of increasing concentrations of nematodes induced higher mortality on Z. pyrina larvae with mean mortality ranging from 28.3% to 100% after 72 h. All three nematodes successfully reproduced and recovered from pest’s cadavers. The highest reproduction was recorded for H. bacteriophora at 5 IJs larva−1 in Z. pyrina. Semi–field experiments using potted walnut seedlings and field trials in a heavily infested walnut orchard during two consecutive years revealed the ability of the aforementioned nematodes to infect and kill Z. pyrina larvae inside the galleries of walnut branches. Overall, this research highlights the ability of all three examined nematodes to find, invade, recycle and effectively infect Z. pyrina larvae; however, S. carpocapsae is comparatively more effective than H. bacteriophora and Acrobeloides K29 under laboratory, semi–field and field conditions. Of significance, the free-living nematode causes high to moderate levels of mortality in Z. pyrina larvae in laboratory and natural conditions.

Automatic Detection of Individual Trees from VHR Satellite Images Using Scale-Space Methods.

This research investigates the use of scale-space theory to detect individual trees in orchards from very-high resolution (VHR) satellite images. Trees are characterized by blobs, for example, bell-shaped surfaces. Their modeling requires the identification of local maxima in Gaussian scale space, whereas location of the maxima in the scale direction provides information about the tree size. A two-step procedure relates the detected blobs to tree objects in the field. First, a Gaussian blob model identifies tree crowns in Gaussian scale space. Second, an improved tree crown model modifies this model in the scale direction. The procedures are tested on the following three representative cases: an area with vitellaria trees in Mali, an orchard with walnut trees in Iran, and one case with oil palm trees in Indonesia. The results show that the refined Gaussian blob model improves upon the traditional Gaussian blob model by effectively discriminating between false and correct detections and accurately identifying size and position of trees. A comparison with existing methods shows an improvement of 10–20% in true positive detections. We conclude that the presented two-step modeling procedure of tree crowns using Gaussian scale space is useful to automatically detect individual trees from VHR satellite images for at least three representative cases.