First Report of Leaf Anthracnose Caused by Phomopsis convolvuli on Field Bindweed in Turkey

Field bindweed (Convolvulus arvensis L.; Convolvulaceae) is a troublesome perennial weed found among many important crops in the world (1). In May of 2007, dying field bindweed plants were found along the edge of a wheat (Triticum aestivum L.) field between Bafra and Taflan, Turkey (41°34.395′N, 35°52.215′E). Lesions on leaves were irregular and variable in size and dark black with green margins. Severely diseased leaves were wilted or dead. Fruiting bodies were not evident on field-collected material. Diseased tissue was surface disinfested and placed on moist filter paper in petri plates. Numerous pycnidia with alpha conidia were observed after 2 weeks. A fungus, designated 24-6, was isolated from the diseased leaves. Cultures on potato dextrose agar (PDA) were floccose with white mycelia and small black stromata. Alpha conidia from pycnidia on inoculated plants were biguttulate, one celled, hyaline, oblong to ellipsoid, and 7.0 to 12.8 × 3.0 to 5.5 μm (mean 10.0 × 3.9 μm). Neither beta conidia nor the teleomorph, Diaporthe sp., were observed on diseased tissue or in cultures. Morphology was consistent with that of Phomopsis convolvuli Ormeno-Nunez, Reeleder & A.K. Watson (2). Alpha conidia were harvested from 12-day-old cultures grown on PDA by brushing the surface of the colonies with a small paint brush, suspending the conidia in sterile distilled water, and filtering through cheesecloth. The conidia were then resuspended in sterile distilled water plus 0.1% polysorbate 20 to arrive at a concentration of 107 conidia/ml. Stems and leaves of seven plants at the 3- to 5-leaf stage were spray inoculated with 10 ml per plant of this aqueous suspension. Inoculated plants and two noninoculated plants were placed in a dew chamber at 24°C in darkness and continuous dew. After 48 h, plants from the dew chamber were moved to a greenhouse bench. Disease severity was evaluated 1 week after inoculation with a rating system based on a scale from 0 to 4, in which 0 = no symptoms, 1 = 1 to 25% necrosis, 2 = 26 to 50% necrosis, 3 = 51 to 75% necrosis, and 4 = 76 to 100% necrosis (2). The average disease rating on inoculated plants was 3.75. No disease was observed on noninoculated plants. P. convolvuli was reisolated from all inoculated plants. Comparison of the internal transcribed spacer (ITS) 1 and 2 sequences with available sequences of a vouchered P. convolvuli specimen (GenBank Nos. U11363, U11417; BPI 748009, FAU649) showed 192 of 193 and 176 of 179 identities, respectively, for the two regions. Nucleotide sequences for the ribosomal ITS regions (ITS 1 and 2, including 5.8S rDNA) were deposited in GenBank (Accession No. FJ710810), and a voucher specimen has been deposited with the U.S. National Fungus Collections (BPI 878927). To our knowledge, this is the second report in the world of leaf anthracnose on field bindweed caused by P. convolvuli. The first report was from Canada (3) of an isolate that was later patented for biological control of C. arvensis (4). References: (1) L. Holm et al. The World's Worst Weeds. University Press of Hawaii, Honolulu, 1977. (2) J. Ormeno-Nunez, et al. Can. J. Bot. 66:2228, 1988. (3) J. Ormeno-Nunez et al. Plant Dis. 72:338, 1988. (4) A. K. Watson et al. U.S. Patent 5,212,086, 1993.

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First Report of Leaf Spot Caused by Colletotrichum cf. linicola on Field Bindweed in Turkey

Plant Disease ◽

10.1094/pdis-92-2-0316a ◽

2008 ◽

Vol 92 (2) ◽

pp. 316-316 ◽

Cited By ~ 2

Author(s):

B. Tunali ◽

D. K. Berner ◽

H. J. Dubin

Keyword(s):

Dna Sequences ◽

Aqueous Suspension ◽

Severe Disease ◽

Leaf Tissue ◽

Malt Extract ◽

Voucher Specimen ◽

First Report ◽

Wheat Field ◽

Leaf Spots ◽

Field Bindweed

Field bindweed (Convolvulus arvensis L., Convolvulaceae) is one of the most problematic weeds in the world (1) and a target of biological control efforts (2). In the summer of 2006, dying field bindweed plants were found in a wheat field near Bafra, Turkey (41°21.197′N, 36°12.524′E). Plants had water-soaked lesions that developed into necrotic leaf spots on most of the leaves, particularly along the leaf margins, and on some stems. In most cases, the leaf spots coalesced, causing the leaves and later plants to wilt and die. Diseased leaves and stems were taken to the Phytopathology Laboratory of the Faculty of Agriculture, Ondokuz Mayis University, Samsun, Turkey. Diseased tissue was surface disinfested and placed on moist filter paper in petri dishes. Numerous acervuli with setae and conidia typical of a Colletotrichum sp. were observed after 2 to 5 days. A fungus, designated 06-01, was isolated from the diseased leaves. Stems and leaves of seven 12-week-old plants were spray inoculated in the laboratory with an aqueous suspension of conidia (106 spores per ml; 10 ml per plant) harvested from 6- to 8-day-old cultures grown on malt extract agar. The plants and two noninoculated checks were placed in a dew chamber at 22°C in darkness and continuous dew. After 48 h, plants from the dew chamber were moved to a greenhouse bench. All plants were watered twice daily. Symptoms were observed 5 days after inoculation. No symptoms were observed on noninoculated plants. Isolate 06-01 was reisolated from all inoculated plants. In the field, 20 inoculated plants became diseased after 20 days with approximately 36% diseased leaf tissue from which 06-01 was consistently reisolated. Diseased tissue and cultures of the fungus were sent to the Foreign Disease-Weed Science Research Unit, USDA/ARS, Fort Detrick, MD. The fungus conformed to the description of Colletotrichum linicola Pethybr. & Laff., which was noted as distinct from C. lini (3). The original description is also different than the description of C. lini (Westerdijk) Tochinai by Sutton (4). Acervuli were sparse, subepidermal, and erumpent. Conidia were hyaline, oblong or cylindrical or somewhat spindle-shaped with dull-pointed ends, guttulate, and 14 to 19 × 4 to 5 μm (mean 17 × 4 μm). Conidiophores were short, simple, hyaline, and emerged from subepidermal stroma. Setae were simple, erect, 3-septate, and dark with hyaline tips. DNA sequences were obtained for the internal transcribed spacer regions (GenBank Accession No. EU000060) and compared with other sequences in GenBank. Sequences from 06-01 matched 100% with one isolate of C. linicola and 99% with two other isolates of C. linicola. These isolates formed a unique clade. However, 06-01 was also 99% identical to other species of Colletotrichum. Thus, species identification is inconclusive. Isolate 06-01 is a destructive pathogen on field bindweed, and severe disease can be produced by inoculation of foliage with an aqueous suspension of conidia. To our knowledge, this is the first report of Colletotrichum on field bindweed. A voucher specimen has been deposited with the U.S. National Fungus Collections (BPI 878174). References: (1) L. Holm et al. The World's Worst Weeds. University Hawaii Press, Honolulu, Hawaii, 1977. (2) G. Defago et al. BioControl 46:157, 2001. (3) G. H. Pethybridge and H. A. Lafferty. Sci. Proc. R. Dublin Soc. 15:359, 1918. (4) B. C. Sutton. The Coelomycetes. Commonw. Mycol. Inst., Kew, England, 1980.

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First Report of Stem Canker of Salsola tragus Caused by Diaporthe eres in Russia

Plant Disease ◽

10.1094/pdis-93-1-0110b ◽

2009 ◽

Vol 93 (1) ◽

pp. 110-110 ◽

Cited By ~ 1

Author(s):

T. Kolomiets ◽

Z. Mukhina ◽

T. Matveeva ◽

D. Bogomaz ◽

D. K. Berner ◽

...

Keyword(s):

United States ◽

Biological Control ◽

Biological Control Agent ◽

Aqueous Suspension ◽

Stem Canker ◽

The United States ◽

Invasive Weed ◽

Voucher Specimen ◽

First Report ◽

Stem Lesions

Salsola tragus L. (Russian thistle) is a problematic invasive weed in the western United States and a target of biological control efforts. In September of 2007, dying S. tragus plants were found along the Azov Sea at Chushka, Russia. Dying plants had irregular, necrotic, canker-like lesions near the base of the stems and most stems showed girdling and cracking. Stem lesions were dark brown and contained brown pycnidia within and extending along lesion-free sections of the stems and basal portions of leaves. Diseased stems were cut into 3- to 5-mm pieces and disinfested in 70% ethyl alcohol. After drying, stem pieces were placed into petri dishes on the surface of potato glucose agar. Numerous, dark, immersed erumpent pycnidia with a single ostiole were observed in all lesions after 2 to 3 days. Axenic cultures were sent to the Foreign Disease-Weed Science Research Unit, USDA, ARS, Ft. Detrick, MD for testing in quarantine. Conidiophores were simple, cylindrical, and 5 to 25 × 2 μm (mean 12 × 2 μm). Alpha conidia were biguttulate, one-celled, hyaline, nonseptate, ovoid, and 6.3 to 11.5 × 1.3 to 2.9 μm (mean 8.8 × 2.0 μm). Beta conidia were one-celled, filiform, hamate, hyaline, and 11.1 to 24.9 × 0.3 to 2.5 μm (mean 17.7 × 1.2 μm). The isolate was morphologically identified as a species of Phomopsis, the conidial state of Diaporthe (1). The teleomorph was not observed. A comparison with available sequences in GenBank using BLAST found 528 of 529 identities with the internal transcribed spacer (ITS) sequence of an authentic and vouchered Diaporthe eres Nitschke (GenBank DQ491514; BPI 748435; CBS 109767). Morphology is consistent with that of Phomopsis oblonga (Desm.) Traverso, the anamorph of D. eres (2). Healthy stems and leaves of 10 30-day-old plants of S. tragus were spray inoculated with an aqueous suspension of conidia (1.0 × 106 alpha conidia/ml plus 0.1% v/v polysorbate 20) harvested from 14-day-old cultures grown on 20% V8 juice agar. Another 10 control plants were sprayed with water and surfactant without conidia. Plants were placed in an environmental chamber at 100% humidity (rh) for 16 h with no lighting at 25°C. After approximately 24 h, plants were transferred to a greenhouse at 20 to 25°C, 30 to 50% rh, and natural light. Stem lesions developed on three inoculated plants after 14 days and another three plants after 21 days. After 70 days, all inoculated plants were diseased, four were dead, and three had more than 75% diseased tissue. No symptoms occurred on control plants. The Phomopsis state was recovered from all diseased plants. This isolate of D. eres is a potential biological control agent of S. tragus in the United States. A voucher specimen has been deposited with the U.S. National Fungus Collections (BPI 878717). Nucleotide sequences for the ribosomal ITS regions (ITS 1 and 2) were deposited in GenBank (Accession No. EU805539). To our knowledge, this is the first report of stem canker on S. tragus caused by D. eres. References: (1) B. C. Sutton. Page 569 in: The Coelomycetes. CMI, Kew, Surrey, UK, 1980. (2) L. E. Wehmeyer. The Genus Diaporthe Nitschke and its Segregates. University of Michigan Press, Ann Arbor, 1933.

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First Report of Leaf Spot Caused by Periconia igniaria on Yellow Starthistle in Russia

Plant Disease ◽

10.1094/pdis-92-6-0983a ◽

2008 ◽

Vol 92 (6) ◽

pp. 983-983 ◽

Cited By ~ 4

Author(s):

T. Kolomiets ◽

L. Pankratova ◽

Z. Mukhina ◽

D. Kassanelly ◽

T. Matveeva ◽

...

Keyword(s):

Aqueous Suspension ◽

Soil Fungus ◽

Aerial Mycelium ◽

Its Sequences ◽

Yellow Starthistle ◽

Invasive Weed ◽

Voucher Specimen ◽

First Report ◽

Russian State ◽

Nutrition Medium

Yellow starthistle (YST), Centaurea solstitialis L., is a weedy plant that is widely distributed in the Krasnodar Region of Russia. It is also an aggressive invasive weed in the western United States and a target of biological control efforts. In the summer of 2006, several hundred diseased plants were found near Taman, Russia. Symptoms of the disease were yellow, water-soaked leaf spots. Diseased leaves were collected, air dried, and sent to the Russian State Collection of Phytopathogenic Organisms at the All Russia Institute of Phytopathology (ARIP). The fungus isolated from the diseased leaves conformed to Periconia igniaria E.W. Mason & M.B. Ellis (teleomorph Didymosphaeria igniaria C. Booth) (1). Colonies of the fungus grew rapidly on potato glucose nutrition medium with aerial mycelium from fluffy to pressed and colorless at the beginning and darkening to black with age. The medium side of the colonies gradually became violet purple to wine colored. Conidiophores had aerial mycelia as much as 550 μm long and 9 to 13 μm wide tapering to 6 to 10 μm. Conidiophores were dark with short, swollen branched stipes. Conidia, formed in short twisted chains, were spherical, dark brown, 7 to 9 μm in diameter, and covered by 1 μm long spines. Yellow starthistle plants were grown in growth chambers with day/night air temperatures of 26 to 28/20 to 22°C, 60 to 70% relative air humidity, and 10,000 lx light for 16 h. Fifteen plants in the rosette stage were spray inoculated with an aqueous suspension of P. igniaria conidia at 5 × 106 conidia/ml and 5 ml per plant. Disease on leaves was observed on all plants 3 to 4 weeks after inoculation when the plants started to bolt. When the plants reached flowering stage, diffused yellow spots were observed on stems and inflorescences and all flowers died. Diseased leaves were surface disinfested and put on potato saccharose nutrition medium. P. igniaria was reisolated from 3 to 5 leaves of each plant and from flowers and stems that developed from 10 inoculated rosettes. Flowers of 10 YST plants were also inoculated with P. igniaria isolated from the previously inoculated plants. Disease developed in the flowers of all inoculated plants, and the symptoms were identical to those observed when rosettes were inoculated and disease followed bolting and flowering. No symptoms developed on four noninoculated plants included in each test. Internal transcribed spacer (ITS) sequences of the fungus were obtained and compared with sequences from GenBank. An uncultured soil fungus and three isolates of P. macrospinosa Lefebvre & Aar.G. Johnson produced the best homology (96%). No sequences for P. igniaria were available for comparison, but the description of P. macrospinosa (conidia 18 to 32 μm in diameter with 2.5 to 6 μm long spines) is clearly different than our isolate. ITS sequences for our isolate have been deposited in GenBank (Accession No. EU367468) and a voucher specimen has been deposited with the U.S. National Fungus Collection (BPI 878355). To our knowledge, this is the first report of P. igniaria causing disease on YST. Live cultures are being maintained at the Russian State Collection of Phytopathogenic Organisms in ARIP. Reference: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, UK, 1971.

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First Report of Leaf Spot Caused by Cercospora bizzozeriana on Hoary Cress in Russia

Plant Disease ◽

10.1094/pdis-92-2-0316c ◽

2008 ◽

Vol 92 (2) ◽

pp. 316-316

Author(s):

Z. M. Mukhina ◽

D. Kassanelly ◽

D. K. Berner ◽

H. J. Dubin

Keyword(s):

Biological Control Agent ◽

Aqueous Suspension ◽

Science Research ◽

Research Unit ◽

Invasive Weed ◽

Voucher Specimen ◽

First Report ◽

Leaf Spots ◽

White Leaf ◽

Hoary Cress

Hoary cress (Lepidium draba (L.) subsp. draba (synonym = Cardaria draba (L.) Desv.) (1), family Brassicaceae, is a common weed in Russia but it is an aggressive invasive weed in the northwestern United States. In the summer of 2006, dying hoary cress plants were found near Kugoyeyskoye in the Krylovskoy area of the Krasnodar Region of Russia. Plants had grayish white leaf spots on most of the leaves. In some cases, the diseased leaf spots dropped out of the leaves producing shot-holes. In most cases, the leaf spots coalesced and the leaves wilted and died. Diseased leaves were collected, air dried, and sent to the quarantine facility of the Foreign Disease-Weed Science Research Unit (FDWSRU), USDA/ARS, Fort Detrick, MD. The air-dried leaves were observed microscopically, and numerous conidiophores and conidia were observed on both sides of leaves within and around the lesions. The fungus isolated (DB06-018) conformed to the description of Cercospora bizzozeriana Saccardo & Berlese (2). Conidiophores were 1 to 5 geniculate, unbranched, pale olive-brown, and uniform in color and width (4 μm). Conidia were multiseptate, hyaline, cylindric, straight to slightly curved, and measured 57 to 171 μm (average 103) long × 3.8 to 6.7 μm (average 4.6) wide. Leaves of rosettes (10 to 15 cm in diameter) of four hoary cress plants were spray inoculated with an aqueous suspension of conidia (1 × 105/ml) and mycelia harvested from 6- to 8-day-old cultures grown on V8 medium. Inoculated plants and two noninoculated plants were placed in a dew chamber at 20°C in darkness and continuous dew. After 96 h, plants were moved from the dew chamber to a greenhouse bench. All plants were watered twice daily. After 12 days, symptoms were observed on all inoculated plants. Symptoms were identical to those observed in the field in Russia. No symptoms were observed on noninoculated plants. C. bizzozeriana was reisolated from the leaves of all symptomatic plants. Nucleotide sequences were obtained for the internal transcribed spacer regions ITS1 and ITS2 and the 5.8S ribosomal RNA gene (GenBank Accession No. EU031780) and aligned with the same sequences obtained from another C. bizzozeriana isolate (GenBank Accession No. DQ370428) collected in Tunisia. There was 100% alignment of the two sequences with no gaps. Both isolates of C. bizzozeriana are destructive pathogens on hoary cress and locally severe epidemics have been observed in both Russia and Tunisia (4). This fungus has also been reported in North America (3) and has the potential as a biological control agent where the weed is a problem. To our knowledge, this is the first report of C. bizzozeriana on L. draba subsp. draba in Russia. A voucher specimen has been deposited with the U.S. National Fungus Collections (BPI 878175). Live cultures are being maintained at FDWSRU. References: (1) I. A. Al-Shehbaz and K. Mummenhoff. Novon 12:5, 2002. (2) C. Chupp. A Monograph of the Fungus Genus Cercospora. C. Chupp, Ithaca, New York, 1953. (3) I. L. Conners. Res. Bra. Can. Dep. Agric. 1251:1, 1967. (4) T. Souissi et al. Plant Dis. 89:206, 2005.

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First Report of Leaf Spot Caused by a Cercosporella sp. on Centaurea solstitialis in Greece

Plant Disease ◽

10.1094/pdis.2004.88.12.1382a ◽

2004 ◽

Vol 88 (12) ◽

pp. 1382-1382 ◽

Cited By ~ 1

Author(s):

F. M. Eskandari ◽

D. K. Berner ◽

J. Kashefi ◽

L. Strieth

Keyword(s):

United States ◽

Biological Control ◽

Biological Control Agent ◽

Aqueous Suspension ◽

The United States ◽

Centaurea Solstitialis ◽

Voucher Specimen ◽

Disease Symptoms ◽

First Report ◽

Leaf Spots

Centaurea solstitialis L. (yellow starthistle [YST]), family Asteraceae, an invasive weed in California and the western United States is targeted for biological control. During the spring of 2004, an epidemic of dying YST plants was found near Kozani, Greece (40°22′07″N, 21°52′35″E, 634 m elevation). Rosettes of YST had small, brown leaf spots on most of the lower leaves. In many cases, these spots coalesced and resulted in necrosis of many of the leaves and death of the rosette. Along the roadside where the disease was found, >100 of the YST plants showed disease symptoms. Diseased plants were collected, air dried, and sent to the quarantine facility of the Foreign Disease-Weed Science Research Unit (FDWSRU), USDA, ARS, Fort Detrick, MD. Diseased leaves were surface disinfested and placed on moist filter paper in petri dishes. Conidiophores and conidia were observed after 48 h. The fungal isolate, DB04-011, was isolated from these diseased leaves. Pathogenicity tests were performed by spray inoculating the foliage of 20 4-week-old YST rosettes with an aqueous suspension of 1 × 106 conidia per ml. Conidia were harvested from 2-week-old cultures grown on modified potato carrot agar (MPCA). Inoculated plants were placed in an environmental chamber at 23°C with 8 h of daily light and continuous dew for 48 h. Inoculated and control plants were moved to a 20°C greenhouse bench and watered twice per day. After 7 days, leaf spots were observed first on lower leaves. After 10–12 days, all inoculated plants showed typical symptoms of the disease. No symptoms developed on control plants. The pathogen, DB04-011, was consistently isolated from symptomatic leaves of all inoculated plants. Disease symptoms were scattered, amphigenous leaf spots in circular to subcircular spots that were 0.2 to 7 mm in diameter and brownish with distinct dark green margins. Intraepidermal stromata, 14 to 77 μm in diameter and pale yellow to brown, were formed within the spots. Conidiophores that arose from the stromata were straight, subcylindrical, simple, 70 to 95 × 2.8 to 4 μm, hyaline, smooth, and continuous or septate with conidial scars that were somewhat thickened, colorless, and refractive. Primary conidia were subcylindrical, slightly obclavate or fusiform, ovoid, 21 to 49 × 5 to 7.5 μm, 0 to 5 septate, hyaline, smooth, had a relatively rounded apex, and the hilum was slightly thickened. Conidial dimensions on MPCA were 11.2 to 39.2 × 4.2 to 7 μm (average 25.5 × 5.5 μm). Koch's postulates were repeated two more times with 20 and 16 plants. On the basis of fungal morphology, the organism was identified as a Cercosporella sp., (1,2; U. Braun and N. Ale-Agha, personal communication). To our knowledge, this is the first report of this genus of fungus parasitizing YST. Results of host range tests will establish if this isolate of Cercosporella has potential as a biological control agent of YST in the United States. A voucher specimen has been deposited with the U.S. National Fungus Collections (BPI 844247). Live cultures are being maintained at FDWSRU and European Biological Control Laboratoryt (EBCL), Greece. References: (1) U. Braun. A Monograph of Cercosporella, Ramularia and Allied Genera (Phytopathogenic Hyphomycetes) Vol. 1. IHW-Verlage, Eching-by-Munich, 1995. (2) U. Braun. A Monograph of Cercosporella, Ramularia and Allied Genera (Phytopathogenic Hyphomycetes) Vol. 2. IHW-Verlage, 1998.

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Nutritive Value of Field Bindweed (Convolvulus arvensis) Roots as a Potential Livestock Feed and the Effect of Aceria malherbae on Root Components

Weed Technology ◽

10.1614/wt-d-14-00112.1 ◽

2015 ◽

Vol 29 (2) ◽

pp. 329-334 ◽

Cited By ~ 5

Author(s):

Brian J Schutte ◽

Leonard Lauriault

Keyword(s):

Crude Protein ◽

Nutritive Value ◽

Neutral Detergent Fiber ◽

Agricultural Field ◽

Convolvulus Arvensis ◽

Perennial Weed ◽

Livestock Feed ◽

Field Bindweed ◽

Root Chemistry ◽

Ruminant Livestock

Crop producers might be able to better manage field bindweed, an aggressive perennial weed, by utilizing tillage to bring roots to the surface where they can be consumed by ruminant livestock. The objectives of this study were to provide first perspectives on forage nutritive value of field bindweed roots and to determine root chemistry responses to Aceria malherbae, an eriophyid mite that has been released for field bindweed biocontrol in the western United States and Canada. To accomplish these objectives, root systems were sampled from A. malherbae-infested and noninfested plants occurring in an agricultural field in eastern New Mexico. Sampling took place during autumn and spring of each year for 3 consecutive yr. Results indicated that A. malherbae reduced taproot diameter and increased root concentrations of Ca, P, and Mg. However, A. malherbae did not affect root concentrations of acid detergent fiber, nonfiber carbohydrates, neutral detergent fiber (NDF), crude protein (CP), and total digestible nutrients (TDN). Overall means for NDF (33.8%), CP (11.6%), and TDN (72.1%) were similar to those reported for forages commonly grown in the region, suggesting that field bindweed roots might positively contribute to nutritional programs of ruminant livestock. These results justify subsequent studies on livestock responses to field bindweed roots and field bindweed responses to targeted root grazing.

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First Report of a Leaf Spot Caused by Cercospora bizzozeriana on Lepidium draba subsp. draba in Tunisia

Plant Disease ◽

10.1094/pd-89-0206a ◽

2005 ◽

Vol 89 (2) ◽

pp. 206-206

Author(s):

T. Souissi ◽

D. K. Berner ◽

H. J. Dubin

Keyword(s):

United States ◽

Biological Control ◽

Biological Control Agent ◽

Aqueous Suspension ◽

The United States ◽

Voucher Specimen ◽

First Report ◽

Leaf Spots ◽

White Leaf ◽

Lepidium Draba

Lepidium draba (L.) subsp. draba (synonym = Cardaria draba (L.) Desv.), commonly known as white-top or hoary-cress (1), family Brassicaceae, is a common weed and emerging problem in wheat in Tunisia. It is also a problematic invasive weed in the northwestern United States and a target of biological control efforts. During the summer of 2002, dying L. draba plants were found around Tunis, Tunisia. Plants had grayish white leaf spots on most of the leaves. In some cases, the leaf spots dropped out of the leaves producing “shot-holes”. In most cases, the leaf spots coalesced, and the leaves wilted and died. Diseased leaves were collected, air-dried, and sent to the quarantine facility of the Foreign Disease-Weed Science Research Unit (FDWSRU), USDA/ARS, Fort Detrick, MD. The air-dried leaves were observed microscopically, and numerous conidiophores and conidia were observed on both sides of the leaves within and around the lesions. The fungus isolated (DB03-009) conformed to the description of Cercospora bizzozeriana Saccardo & Berlese (2). Conidiophores were unbranched, pale olive-brown, 1 to 5 geniculate, and uniform in color and width. Conidia were hyaline, straight to slightly curved, multiseptate, and 57 to 171 × 3.8 to 6.7 µm (average 103 to 4.6 µm). Stems and leaves of 12 rosettes (10 to 15 cm in diameter) of 6-week-old L. draba plants were spray inoculated with an aqueous suspension of conidia (1 × 105/ml) harvested from 6- to 8-day-old cultures grown on carrot leaf decoction agar. Six of the plants and two noninoculated plants were placed in a dew chamber at 22°C in darkness and continuous dew. The other half of the plants and two noninoculated plants were placed on a greenhouse bench at approximately 25°C and covered with clear polyethylene bags. After 72 h, plants from the dew chamber were moved to a greenhouse bench, and the bagged plants were uncovered. All plants were watered twice daily. After 9 days, symptoms were observed on the plants that had been bagged but not on the plants from the dew chamber. Symptoms were identical to those observed in the field in Tunisia and included “shot holes”. No symptoms were observed on noninoculated plants. C. bizzozeriana was reisolated from the leaves of all symptomatic plants. Completion of Koch's postulates was repeated with an additional five plants. This isolate of C. bizzozeriana is a destructive pathogen on L. draba subsp. draba, and severe disease can be produced by inoculation of foliage with an aqueous suspension of conidia. This isolate is a good candidate for mycoherbicide development in Tunisia where the weed and pathogen are indigenous. However, some commercially grown Brassica species were found susceptible to this isolate, which will preclude its use as a classical biological control agent in the United States. To our knowledge, this is the first report of C. bizzozeriana on L. draba subsp. draba in Tunisia. A voucher specimen has been deposited at the U.S. National Fungus Collections (BPI 843753). Live cultures are being maintained at FDWSRU and the Institut National Agronomique de Tunisie, Tunis, Tunisia. References: (1) I. A. Al-Shehbaz and K. Mummenhoff. Novon 12:5, 2002. (2) C. Chupp. A Monograph of the Fungus Genus Cercospora. C. Chupp, Ithaca, New York, 1953.

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First Report of Anthracnose of Mile-a-Minute (Persicaria perfoliata) Caused by Colletotrichum cf. gloeosporioides in Turkey

Plant Disease ◽

10.1094/pdis-03-12-0282-pdn ◽

2012 ◽

Vol 96 (10) ◽

pp. 1578-1578

Author(s):

D. K. Berner ◽

C. A. Cavin ◽

I. Erper ◽

B. Tunali

Keyword(s):

Biological Control ◽

Rating Scale ◽

Biological Control Agent ◽

Aqueous Suspension ◽

Botanical Garden ◽

Control Agent ◽

Internal Transcribed Spacers ◽

Voucher Specimen ◽

First Report ◽

Persicaria Perfoliata

Mile-a-minute (Persicaria perfoliata (L.) H. Gross; family: Polygonaceae) is an exotic annual barbed vine that has invaded the northeastern USA and Oregon (2). In July of 2010, in a search for potential biological control pathogens (3), diseased P. perfoliata plants were found along the Firtina River near Ardesen, Turkey. Symptoms were irregular dark necrotic lesions along leaf margins and smaller irregular reddish lesions on the lamellae of leaves. Symptomatic leaves were sent to the quarantine facility of FDWSRU, USDA, ARS in Ft. Detrick, MD, for pathogen isolation and testing. Symptomatic leaves were excised, surface disinfested in 0.615% NaOCl, and then incubated for 2 to 3 days in sterile moist chambers at 20 to 25°C. Numerous waxy sub-epidermal acervuli with 84-μm-long (mean) black setae were observed in all of the lesions after 2 to 3 days of incubation. Conidiophores within acervuli were simple, short, and erect. Conidia were one-celled, hyaline, guttulate, subcylindrical, straight, 12.3 to 18.9 × 3.0 to 4.6 μm (mean 14.3 × 3.7 μm). Pure cultures were obtained by transferring conidia onto 20% V-8 juice agar. Appressoria, formed 24 h after placing conidia on dialysis membrane over V-8 juice agar, were smooth, clavate, aseptate, regular in outline, and 6.4 to 10.0 × 5.1 to 7.2 μm (mean 7.5 × 6.6 μm). These characters conformed to the description of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. (1). A voucher specimen was deposited in the U.S. National Fungus Collections (BPI 882461). Nucleotide sequences for the internal transcribed spacers (ITS 1 and 2), directly sequenced from ITS 1 and ITS 4 standard primers (4), were deposited in GenBank (JN887693). A comparison of these sequences with ITS 1 and 2 sequences of the C. gloeosporioides epitype IMI 356878 (GenBank EU 371022) (1) using BLAST found 479 of 482 identities with no gaps. Conidia from 14-day-old cultures, in an aqueous suspension of 1.0 × 106 conidia ml–1, were spray-inoculated onto healthy stems and leaves of twenty 30-day-old P. perfoliata plants. Another 10 plants were not inoculated. All plants were placed in a dew chamber at 25°C for 16 h with no lighting. They were then placed in a 20 to 25°C greenhouse with a 14-h photoperiod. Light was generated using 400W sodium vapor lights. Lesions developed on leaves and stems of all inoculated plants after 7 days, and symptoms were the same as observed in the field. Each plant was rated weekly for disease severity on a 0 to 10 rating scale where 0 = no disease symptoms and 10 = 100% symptomatic tissue. After 28 days, the average disease rating of inoculated plants was 3.95 ± 0.94. No disease developed on noninoculated plants. C. gloeosporioides was reisolated from all inoculated plants. Host range tests will determine the potential of this isolate as a biological control agent for P. perfoliata. To our knowledge, this is the first report of anthracnose caused by C. gloeosporioides on P. perfoliata. References: (1) P. F. Cannon et al. Mycotaxon 104:189, 2008. (2) J. T. Kartesz and C. A. Meacham. Synthesis of the North American Flora, Version 1.0., North Carolina Botanical Garden, Chapel Hill, N.C. 1999. (3) D. L. Price et al. Environ. Entomol. 32:229, 2003. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, Inc., San Diego, CA, 1990.

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Exserohilum monoceras, Newly Reported on Late Watergrass in Turkey

Plant Disease ◽

10.1094/pdis-12-10-0867 ◽

2011 ◽

Vol 95 (4) ◽

pp. 497-497

Author(s):

I. Erper ◽

H. Mennan ◽

U. Budak ◽

E. Kaya Altop

Keyword(s):

Biological Control Agent ◽

Cropping Systems ◽

Aqueous Suspension ◽

Control Agent ◽

Infected Leaf ◽

Commonwealth Mycological Institute ◽

Distilled Water ◽

Weed Species ◽

Leaf Spots ◽

The World

Echinochloa species are major weeds in rice-cropping systems and are among the most noxious weeds in the world. Throughout the world, Echinochloa oryzicola Vasing, (late watergrass) is one of the most important and serious weed species of this genus. In September 2010, punctiform, purplish dark brown leaf spots were observed on leaves and sheaths of Echinochloa oryzicola in a rice field in Terme, Turkey (41°13.412′N, 36°56.248′E). Individual lesions ranged from 1 to 3 mm in diameter. Infected leaf and sheaths were surface disinfected for 1 min in 1% NaOCl, plated on potato dextrose agar (PDA), and incubated at 25°C. Colonies of pure cultures on PDA turned to dark green colonies with increasing age. Conidia were 87 to 147 (120) × 15 to 21 (19) μm (n = 50), 6 to 10 pseudoseptate, straight or slightly curved, fusiform, tapering gradually toward the base, pale-to-dark straw colored, smooth, with a small protruding plenum-type hilum. The fungus was identified as Exserohilum monoceras (Drechsler) Leonard & Suggs based on its micromorphology and cultural features (1,2). Conidia were harvested from 3-week-old cultures grown on PDA by brushing the surface of the colonies with a small paint brush, suspending the conidia in sterile distilled water and filtering through cheesecloth for pathogenicity tests. Conidia were then diluted in sterile distilled water plus 0.1% polysorbate 20 to a concentration of 1 × 106 conidia/ml. Leaves and stems of Echinochloa oryzicola at the three-leaf stage were spray inoculated with 10 ml of this aqueous suspension per plant. Three inoculated plants and three noninoculated plants were placed in a dew chamber at 18 to 22°C with continuous dew, and after 48 h, plants were moved to a greenhouse bench. Symptoms, similar to those originally observed in the field, began to appear on the leaf and sheaths approximately 10 days later and E. monoceras was reisolated, successfully completing Koch's postulates. No symptoms developed on the control plants. E. monoceras has also been reported on Echinochloa oryzicola in Japan (3). To our knowledge, this is the first report of leaf spot on Echinochloa oryzicola caused by E. monoceras in Turkey where the fungus may have potential as a biological control agent. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute. Kew, Surrey, England, 1971. (2) M. Sisterna and R. Bezus. Plant Dis. 85:803, 2001. (3) H. Tsukamoton et al. Ann. Phytopathol. Soc. Jpn. 64:526, 1998.

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First Report of Sclerotium rolfsii on Ascocentrum and Ascocenda Orchids in Florida

Plant Disease ◽

10.1094/pdis-93-9-0963b ◽

2009 ◽

Vol 93 (9) ◽

pp. 963-963 ◽

Cited By ~ 7

Author(s):

R. A. Cating ◽

A. J. Palmateer ◽

R. T. McMillan

Keyword(s):

Sclerotium Rolfsii ◽

The United States ◽

South Florida ◽

Plant Industry ◽

Voucher Specimen ◽

First Report ◽

5.8S Rdna ◽

Southern Blight ◽

Host Fungus ◽

Symptomatic Tissue

Southern blight caused by Sclerotium rolfsii is known to occur on several economically important orchid hosts, including Vanda species and hybrids (1–3). In the summer and fall of 2008, an outbreak of southern blight on Vanda orchids was seen in several commercial nurseries and landscapes throughout South Florida. More than a dozen orchids were affected at one of the locations, and symptoms of S. rolfsii were observed on Ascocentrum and Ascocenda orchids, which are also common in the trade and demand a resale value ranging from $20 to $150 for specimens in bloom. Affected Ascocentrum and Ascocenda orchids were found severely wilted at the apex, while around the base of the plants, tan, soft, water-soaked lesions were present. As the lesions progressed, leaves around the base of the plants began to fall off, leaving the stems bare. After 2 days, white, flabellate mycelium was seen progressing up the stem and numerous, tan-to-brown sclerotia were present. Leaves and portions of the stems were plated on acidified potato dextrose agar (APDA) and grown at 25°C. White, flabellate mycelium and tan sclerotia approximately 2 mm in diameter were produced in culture and microscopic examination revealed the presence of clamp connections. The fungus was identified as S. rolfsii and a voucher specimen was deposited with the ATCC. A PCR was performed on the ITS1, 5.8S rDNA, and ITS2 and the sequence was deposited in GenBank (Accession No. GQ358518). Pathogenicity of an isolate was tested by placing 6-mm plugs taken from APDA plates directly against the stem of five different Ascocentrum and Ascocenda orchids. Five Ascocentrum and Ascocenda orchids were inoculated with 6-mm plugs of plain APDA and five were untreated controls. Plants were housed under 50% shade, 60 to 95% humidity, and temperatures ranging from 75 to 88°F. Within 7 days, all inoculated plants developed symptoms that were identical to those observed on original plants and S. rolfsii was consistently reisolated from symptomatic tissue. Ascocentrum and Ascocenda were previously reported under miscellaneous orchid species and hybrids as hosts for S. rolfsii (1). However, this report was highly ambiguous and the most current edition does not report the host fungus combination (2). To our knowledge, this is the first report of S. rolfsii affecting Ascocentrum and Ascocenda orchids. References: (1) S. A. Alfieri, Jr., et al. Diseases and Disorders of Plants in Florida. Bull. No. 11. Division of Plant Industry, Gainesville, FL, 1984. (2) S. A. Alfieri, Jr., et al. Diseases and Disorders of Plants in Florida. Bull. No. 14. Division of Plant Industry, Gainesville, FL, 1994. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989.

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