Fungal pathogens associated with young grapevine decline in the Southern Turkey vineyards

Young grapevine decline is a common and important disease caused by fungal plant pathogens in Turkey vineyards. Every year many grape growers face this problem in their vineyards and seek solutions to cope with it. The aims of the study were to examine fungal pathogens of young grapevine decline in Southern Turkey and to determine pathogenicity of fungi involved in the disease. Twenty vineyards (2–3 years-old, located in Adana, Mersin and Gaziantep cities) were surveyed in March 2018 and declining whole plants were sampled and processed for mycological procedures. Sub-cultured fungal colonies were examined for colony morphology and conidia-conidiophore shapes under light microscope. For molecular identification, ITS, beta-tubulin, histone and TEF1-alpha gene regions were amplified with PCR using appropriate primers and PCR products were subsequently sequenced. The sequences were compared with those deposited in the NCBI GenBank database using the BLASTn program and fungal identifications were confirmed by getting accession numbers. Pathogenicity tests were fulfilled under greenhouse conditions for two months. The results indicated that Botryosphaeria Dieback and Black Foot fungi were two most common pathogen groups, while Petri Disease and Diaporthe Dieback pathogens had minor incidence. Although a variety of Fusarium species were isolated from declined vines, only F. brachygibbosum and F. solani were found to have considerable role in disease occurrence

Biocontrol of phytophthora capsici on pepper plants by Bacillus megaterium strains

Phytophthora blight or crown blight of peppers, caused by Phytophthora capsici Leonian, is one of the most important diseases of pepper in the eastern Mediterranean region of Turkey. The possibility to reducedisease severity using phosphate-solubilizing bacteria was investigated in growth room and field experiments. The pepper plants, inoculated with the pathogen after pre-inoculation with three phosphate-solubilizing strains of Bacillus megaterium employed alone or in combination, were monitored for growth parameters and disease severity. Inoculation with the selected strains significantly reduced disease severity in field experiments and two strains increased the yield by 36.2 and 47.7% compared to untreated controls. Bacteria were identified by fatty acid methyl ester (FAME) profiling

Effect of wheat cultivars, fertilizers, and fungicides on Fusarium foot rot disease of wheat

Fusarium culmorum is a principal causal agent of root, crown, and foot rot disease in the wheat-growing areas of Turkey. The effects of different fertilization practices, fungicide sprays, and cultivar reactions of 12 wheat varieties were investigated for disease development in greenhouse conditions in 2006–2007. The fertilizers used in the experiments significantly reduced disease by 27.5%– 54.7% compared to the nonfertilized control. The plants fertilized with calcium ammonium nitrate (26% N) or composite NPK (15%, 15%, 15%) showed fewer disease symptoms than those fertilized with NPK (20%, 20%, 0%) in the presowing applications. On the other hand, foot rot severity was lower with ammonium nitrate (33% N) than urea (46% N) when applied as a supplement in the 25th and 45th growth stages of the Zadoks scale. Furthermore, fungicide sprays and seed dressing treatments also decreased foot rot symptoms. Seed treatment with tebuconazole lowered disease severity in the subcrown internode compared to the control and it was overall the most effective fungicide with 47.8% efficacy. When plants were sprayed with fluquinconazole, tebuconazole, or epoxyconazole + carbendazim (two times at Zadoks growth stages 31 and 45), disease severity decreased by 96.3%, 93.9%, and 91.0%, respectively. In the cultivar reaction tests, no stable or considerable tolerance was observed in the 12 wheat varieties against foot rot. It may be concluded from this study that fertilizer forms and fungicide preference can play an important role where Fusarium foot rot is the main problem in wheat-growing areas. © TÜBİTAK

First report of wood canker caused by Lasiodiplodia exigua and Neoscytalidium novaehollandiae on grapevine in Turkey

[No abstract available

First report of Ilyonectria liriodendri associated with black foot disease of grapevine in Turkey

Grapevine trunk diseases have been an increasing problem of Turkey vineyards in recent years. A study was conducted in nine Chardonnay (grafted on 110R) vineyards to determine the incidence and the causal agents of grapevine trunk diseases in Sarkoy, Tekirdag (northwest of Turkey) in 2014. The vines with tiger-striped leaves, and declining, local drying, or dead arm symptoms (27.3% of all inspected 23291 vines) were recorded and branch, trunk, and rootstock samples (three samples from each vineyard) were taken for laboratory examinations. Dark brown and black spots in cross sections and blackish streaks in longitudinal sections were observed in wood of some rootstocks. Symptomatic tissues were surface disinfested with 95% ethanol and flame sterilized. The internal tissues were plated onto potato dextrose agar amended with tetracycline (0.01%). Petri dishes were incubated at 24°C in the dark for 18 days and floccose to felted colonies, which varied in color from dark orange to dark brown with age, developed (in one vineyard, with 24.3% isolation frequency) around wood chips. Pure cultures of the isolate (MBAi232) produced 1 to 3-septate, straight or slightly curved, cylindrical macroconidia (32 to 38 × 4.9 to 5.7 µm) and a few microconidia. Chlamydospores were brown, ovoid (12 to 17 × 10 to 17 µm), and mostly in short and intercalary in chains. According to morphological characteristics, the isolate resembled Ilyonectria liriodendri with species nomenclature based on the work of Halleen et al. 2006. For molecular identification, fungal DNA was extracted from mycelium and ribosomal DNA fragments (ITS1, 5.8S ITS2 rDNA) and ß-tubulin gene were amplified with ITS 4-5, Bt 2a-2b primers (White 1990; Glass and Donaldson 1995) and sequenced. The sequences were compared with those deposited in GenBank and the isolate showed 99% similarity with I. liriodendri isolates JF735261 (ITS) and KF511973 (ß-tubulin). The sequences were deposited as NCBI GenBank Accession Nos. KP271987, KP271986 for ITS, and ß-tubulin, respectively. Pathogenicity tests were conducted under greenhouse conditions (24°C, 16/8h day/night, 70% RH) on own-rooted grapevine (Vitis vinifera) seedlings cv. Chardonnay using the isolate of I. liriodendri. Plants were removed from the rooting bench, and the roots were slightly trimmed and dip-inoculated with a 106/ml conidial suspension of the isolate for 60 min (Cabral et al. 2012). After inoculation, the rooted cuttings were planted in 1-liter bags containing a mixture of soil, peat, and sand (2:1:1, v/v/v), and maintained in the greenhouse. Sterile distilled water was used for inoculation of negative control plants. Ten vines were inoculated with the isolate and 5 vines were not inoculated. The experiment was repeated twice. After 4 months of incubation, seedlings were examined for vascular discoloration and recovery of fungal isolate. Blackish-brown discoloration of xylem vessels and necrosis in the basal ends and roots were visible in inoculated but not in uninoculated control seedlings. Slight leaf wilting was also observed in some plants. The fungal isolate was successfully reisolated (by 70.5%) from inoculated but not from uninoculated ones. To our knowledge, this is the first report of I. liriodendri causing black-foot disease of grapevine in Turkey. © 2015 The American Phytopathological Society

First report of anthracnose caused by Colletotrichum spinaciae on spinach in the Mediterranean region of Turkey

During 2011 to 2013, significant anthracnose symptoms were observed in spinach (Spinacia oleracea L.) at different times of the year in Hatay, Adana, and Mersin provinces in the Mediterranean Region of Turkey. A survey was performed in the affected regions, which included 11 fields in Hatay, 5 fields in Adana, and 12 fields in Mersin provinces (18 and 30 samples per location). Disease prevalence (percentage of fields showing foliar symptoms on plants) in these locations ranged between 40 and 75%. Symptoms included small, circular, water-soaked, tan-colored lesions (10 to 20 mm) on both young and old leaves. Older lesions became thin and papery, followed by larger chlorotic, blighted, and necrotic symptoms. Under wet or humid conditions, mature lesions produced dark acervuli with setae (50 to 100 µm long). Symptomatic tissues, taken from surface-sterilized infected leaves, were plated on spinach dextrose agar (SDA, juice of 250 g spinach, 20 g dextrose, 20 g agar in 1 liter distilled water) and incubated for 7 to 10 days at 25°C. The fungus produced a cottony white to pale-gray mycelium with hyaline, one-celled, falcate conidia (17 to 28 × 2.5 to 6 µm) borne on conidiophores in acervuli. Based on disease symptoms and morphological characters, the pathogen was identified as Colletotrichum spinaciae (Ellis & Halst) (Damm et al. 2009). For molecular identification, DNA was extracted from mycelium, actin and ß-tubulin (TUB 2) genes were amplified with ACT512F-ACT793R and T1-Bt2b primers (Carbone and Kohn 1999; Glass and Donaldson 1995), and sequenced. The sequences were compared by BLAST search to the GenBank database and showed 99% similarity to C. spinaciae isolates (Accession Nos. GU227945 and GU228141). The DNA sequences were deposited into GenBank under Accession Nos. KP898448 and KR080474 for actin and beta-tubulin genes. To fulfill Koch’s postulates, pathogenicity tests were performed on leaves of fifteen 4- to 6- week-old spinach seedlings (cv. Matador) by spraying with conidial suspension (105 conidia per ml of sterile water) of each isolate of C. spinaciae. Control plants were treated with sterile distilled water only. All plants were covered with a clear polyethylene bags and incubated at 20°C for 48 h. The bags were removed, and plants were maintained in a dew chamber for 21 days at 60 to 70% relative humidity. Foliar symptoms identical to those observed in spinach fields were visible 14 to 21 days after inoculation. No lesions developed on the control plants. The experiments were repeated twice. The pathogen was readily reisolated on SDA from inoculated plants. The disease has been previously reported from Canada (Cerkauskas et al. 1991), North America (Correll et al. 1994), and Australia (Washington et al. 2006). To our knowledge, this is the first report of C. spinaciae on spinach in the Mediterranean Region of Turkey. © The American Phytopathological Society

First report of Phytopythium vexans causing root and collar rot of Kiwifruit in Turkey

Kiwifruit (Actinidia deliciosa L.) production in Turkey began at the end of the 21st century and is increasing each year. Kiwifruit is mostly grown in the Marmara and Black Sea regions of Turkey. A survey was carried out in 2015 in three provinces of Turkey (Bursa, Kocaeli, and Yalova) to determine the provenance of fungal pathogens on kiwifruit. In eight kiwi orchards of three provinces, root and collar rot symptoms with reddish brown to dark brown lesions were observed on 2 to 20% of the kiwi vines. Above ground symptoms consisted of leaf necrosis, leaf curling, and a general decline of the plants. Isolations were made by exciting pieces of symptomatic root and collar regions. They were surface sterilized by dipping the pieces in 1% sodium hypochlorite for about 1 to 2 min and plating them on 1/4 strength potato dextrose agar (PDA) modified with streptomycin sulfate and neomycin. A number of Phytophthora-like colonies with spherical zoospores, ovoid to globose oogoni, and slow growing whitish mycelium, were isolated. All isolates produced sporangia with prominent papilla. One representative isolate was selected for each province for species level identification by DNA sequencing. Genomic DNA was extracted from mycelium with CTAB protocol (Xu and Leslie 1996). Extracted DNA templates were amplified and sequenced for rDNA internal transcribed spacer (ITS), the large subunit (LSU) rDNA, and cytochrome oxidase I (coxI) gene regions using ITS4/ITS6 (White et al. 1990), NL1/NL4 (Baten et al. 2014), and FM85mod/OomCOILevup (Robideau et al. 2011) primer sets, respectively. NCBI BLAST results showed 99 to 100% similarity with the ITS, LSU, and coxI sequences of Phytopythium vexans in GenBank (KT337684.1, AY598713.1, HQ665090.1, AB690604, AB690608, HQ708447, KT692908.1, and KT692907.1, respectively). The sequences were submitted to GenBank and given accession numbers KY024339, KY024340, and KY024341 for ITS-5.8S gene rDNA; KY024342, KY024343, and KY024344 for LSU rDNA; and KY473919, KY473920, and KY473921 for coxI gene regions, respectively. To complete Koch’s postulates, a pathogenicity test was performed on 1-year-old potted kiwifruit (cv. Hayward) plants. The isolates were grown on 1/4 strength PDA at 26°C for 7 days prior to inoculation. A 5-mm cork borer was used to produce injury at the interface of roots and stems of kiwifruit plants followed by placing 5-mm mycelial agar plugs, and covered with Parafilm. Five plants were treated with PDA plugs as controls. Necrotic lesion development was first observed after 18 days of inoculation, and at 40 days, over 65% of inoculated plants exhibited symptoms similar to those observed in the field. However, control plants remained healthy and asymptomatic. Reisolation of the pathogen from the inoculated plants confirmed that P. vexans is the causal agent of root and collar rot of kiwifruit. To our best knowledge, this is the first report of P. vexans causing root and collar rot of kiwifruit in Turkey, and this report will serve as the foundation of future studies aiming for further characterization and management of root and collar rot of kiwifruit. © 2017, American Phytopathological Society. All rights reserved

Fungal trunk pathogens of Sultana Seedless vineyards in Aegean region of Turkey

In recent years, grapevine trunk diseases have become a problem in Sultana Seedless vineyards of Manisa and Izmir provinces (Aegean Region, Turkey). A field survey was conducted in 2013 in these provinces (in 8 cities and 80 vineyards) to determine disease incidence, fungal species associated with grapevine trunk diseases and pathogenicity. Symptomatic vines were grouped by two different grapevine trunk disease symptoms: (1) typical tiger-striped leaves, (2) dead arm, shoot decline or apoplexy. Over 80% of vineyards in these areas were positive for at least one characteristic trunk disease symptom. Incidence of tiger-stripe symptom ranged from 2.9-15% and incidence of apoplexy ranged from 0-4.2%. Eight fungal species in five fungal families were identified from declining grapevines based on morphological and molecular (ITS, ß-tubulin and EF1-a) studies including, Botryosphaeria dothidea, Diplodia seriata, Lasiodiplodia theobromae, Neofusicoccum parvum, Diaporthe ampelina, Phaeomoniella chlamydospora, Togninia minima and Fomitiporia mediterranea. Overall, D. ampelina was the most frequently recovered fungus from symptomatic grapevine tissues followed by botryosphaeriaceous fungi, P. chlamydospora, F. mediterranea and T. minima. Pathogenicity tests confirmed all eight fungi as pathogens of grapevine in these regions with N. parvum being the most virulent among the fungi tested. © Firenze University Press