First Report of Twig and Branch Dieback of English Walnut (Juglans regia) Caused by Neofusicoccum mediterraneum in California

California produces 99% of the U.S. English walnut crop with more than 30 cultivars on ~89,000 ha. Production for 2008 was ~436,000 tons with a value of $527 million. In early summer of 2009 and 2010, branch and twig dieback of English walnut (Juglans regia L.) was detected in orchards in Yolo County and submitted to our diagnostic laboratory. Disease symptoms included death of twig tips, branch dieback, wood lesions, and canker formation. Pycnidia were embedded within the bark of dead twigs. Conidia from pycnidia were hyaline, fusoid-ellipsoidal, widest usually in the middle, and 21 to 24 (–27) × 5 to 7 μm (n = 30). Isolations from cankers yielded the fungus Neofusicoccum mediterraneum Crous, M.J. Wingf. & A.J.L. Phillips (1). Fungal colonies of N. mediterraneum grew light olive green to gray on potato dextrose agar, becoming dark olive green with age. Identification of fungal isolates was confirmed by sequence comparison of Californian isolates with ex-type (CBS 121558) sequences in GenBank (3) using the internal transcribed spacer region of the rDNA, a portion of the β-tubulin gene, and part of the translation elongation factor. Sequences of Californian isolates (GenBank HM443604–HM443609) were identical to the ex-type sequences for all three genes. Previous studies in California reported the occurrence and pathogenicity of N. mediterraneum into grapevine (Vitis vinifera L.) (3) and almond trees (Prunis dulcis L.) (2). Inderbitzin et al (2) investigated the host range of N. mediterraneum in California and reported the occurrence of pycnidia on English walnut trees. However, this study did not investigate the pathogenicity of N. mediterraneum on this host. In the current study, the pathogenicity of N. mediterraneum in J. regia cvs. Hartley and Chandler was investigated in an orchard at UC Davis using two fungal isolates. Pathogenicity tests were performed by inoculating eight 2- to 4-year-old branches of mature J. regia trees. Inoculations were made in June 2009 with a 5-mm cork borer to remove bark and placing an 8-day-old 5-mm-diameter agar plug bearing fresh mycelium of the fungal isolates directly into the fresh wound, mycelium side down. An additional eight branches of each cultivar were inoculated with noncolonized agar plugs to serve as controls. Inoculated wounds were covered with petroleum jelly and wrapped with Parafilm to retain moisture. Branches were harvested after 10 months of incubation and checked for canker development. The extent of vascular discoloration was measured in each branch and isolations were made from the edge of discolored tissue to confirm Koch's postulates. Statistical analyses were performed with analysis of variance and Dunnett's t-test to assess significant differences in the extent of vascular discoloration between inoculations with N. mediterraneum and the control. Necrosis length for the two isolates averaged 131.5 mm in Hartley branches and 110 mm in the Chandler branches. Average necrosis lengths in the control branches were 18.5 mm and 16.7 mm, respectively, significantly lower (P < 0.05) than the average necrosis length found in branches inoculated with N. mediterraneum. Fungal recovery was 75% in both varieties. To our knowledge, this study is the first report of N. mediterraneum as a pathogen of J. regia trees in California. References: (1) P. W. Crous et al. Fungal Planet 19, 2007. (2) P. Inderbitzin et al. Mycologia. Online publication. doi:10.3852/10-006, 2010. (3) J. R. Úrbez-Torres et al. Plant Dis. 94:785, 2010.

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First Report of Calosphaeria pulchella Associated with Branch Dieback of Sweet Cherry Trees in California

Plant Disease ◽

10.1094/pdis-94-9-1167a ◽

2010 ◽

Vol 94 (9) ◽

pp. 1167-1167 ◽

Cited By ~ 4

Author(s):

F. P. Trouillas ◽

J. D. Lorber ◽

F. Peduto ◽

J. Grant ◽

W. W. Coates ◽

...

Keyword(s):

Sweet Cherry ◽

Prunus Avium ◽

Large Diameter ◽

The United States ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Agar Plug ◽

Vascular Discoloration ◽

Branch Dieback ◽

Cherry Trees

California is the second largest sweet cherry producer in the United States with approximately 10,800 ha and an average annual crop value of approximately $150 million. Perennial canker diseases constitute major threats to the cherry industry productivity by reducing tree health, longevity, and yields. During the course of summer 2006, we observed severe limb and branch dieback of sweet cherry (Prunus avium L.) in San Joaquin, San Benito, Contra Costa, and Stanislaus counties of California. Isolation from diseased branches repeatedly yielded the fungus Calosphaeria pulchella (Pers.: Fr.) J. Schröt. (1,2). Cankers and vascular necroses had developed in tree limbs and branches, generally initiating from the heart wood and later spreading into the sapwood. External symptoms of disease may be unapparent throughout the early stages of infection, particularly in large diameter shoots. Older infections often appeared as wilted leaves. Branches and trunks affected with cankers from which C. pulchella was isolated also generally bore perithecia of C. pulchella beneath the periderm. Perithecia were nonstromatic and arranged in dense, circinate groups, with elongated necks converging radially and fissuring the periderm. Asci were unitunicate, clavate, and 45 to 55 × 5 to 5.5 μm. Ascospores were allantoid to suballantoid, hyaline, and 5 to 6 × 1 μm. Colonies on potato dextrose agar (PDA) were dark pink to red in their center with a white margin. Conidia were hyaline, allantoid to oblong-ellipsoidal, and (3–) 4 to 6 (–9) × 1.5 to 2 (–2.5) μm. Identification of C. pulchella isolates also was confirmed by sequence comparison in GenBank database using the internal transcribed spacer region (ITS1-5.8S-ITS2) of the rDNA. Sequences of California isolates shared 100% similarity with C. pulchella reference isolate CBS 115999 (EU367451) (2). ITS sequences of the California isolates used in this study were deposited into GenBank (Nos. HM237297 to HM237300). Pathogenicity of four isolates recovered from the margin of active cankers was determined by branch inoculations. In December 2006, 2- to 4-year-old twigs of P. avium cv. Bing were inoculated with a 5-mm cork borer to remove bark and by placing an agar plug from the growing margin of 8-day-old colonies directly into the fresh wound, mycelium side down. Ten branches per isolate were inoculated. Ten control shoots were inoculated with noncolonized agar plugs. Inoculations were covered with vaseline and wrapped with Parafilm to retain moisture. Branches were harvested in July 2007 and taken to the laboratory to be examined for canker development, and the extent of vascular discoloration in each branch was assessed. Isolations from the edge of discolored tissue were conducted to fulfill Koch's postulates. After 8 months, C. pulchella was reisolated from 100% of the inoculated branches. Length of vascular discoloration averaged 62.5 mm in branches inoculated with the four C. pulchella isolates and 16.5 mm in the control twigs. No fungi were reisolated from the slightly discolored tissue of the controls. To our knowledge, this study constitutes the first report of C. pulchella as a pathogen of sweet cherry trees in California. References: (1) M. E. Barr. Mycologia 77:549, 1985. (2) U. Damm et al. Persoonia 20:39, 2008.

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First Report of Phytophthora nicotianae and P. citricola Associated with English Walnut Decline in Europe

Plant Disease ◽

10.1094/pdis.2003.87.3.315b ◽

2003 ◽

Vol 87 (3) ◽

pp. 315-315 ◽

Cited By ~ 1

Author(s):

A. Belisario ◽

M. Maccaroni ◽

A. M. Vettraino ◽

A. Vannini

Keyword(s):

Lateral Roots ◽

Juglans Regia ◽

The United States ◽

Phytophthora Nicotianae ◽

Malt Extract ◽

Veneto Region ◽

Internal Transcribed Spacer Region ◽

Campania Region ◽

First Report ◽

English Walnut

English (Persian) walnut (Juglans regia), among the most widely cultivated species of Juglans worldwide, is cultivated primarily for fruit production but also for timber. In the last 10 years, walnut decline causing leaf yellowing, sparse foliage, overall decline, and plant death has increased in Italian commercial orchards. In Italy, Phytophthora cactorum, P. cambivora, P. cinnamomi, and P. cryptogea are associated with this disease (1,4). Over the last 5 years, P. cinnamomi was the most widely isolated and destructive species (1). Recently, a different species of Phytophthora was isolated from diseased roots and soil from around lateral roots of 10 declining trees in two orchards in the Veneto Region of northern Italy. Another species of Phytophthora was isolated consistently from rotted roots of declining walnut trees in two orchards in the Campania Region of southern Italy. Phytophthora spp. were isolated directly from plant material or Rhododendron spp. leaf baiting on soil samples with PARBhy selective medium (10 mg of pimaricin, 250 mg of ampicillin [sodium salt], 10 mg of rifampicin, 50 mg of hymexazol, 15 mg of benomyl, 15 g of malt extract, 20 g of agar in 1,000 ml of H2O). Two species of Phytophthora were identified based on morphological and cultural characteristics (2). The species from trees in the Veneto Region was identified as P. nicotianae. All isolates produced papillate, spherical to obturbinate, occasionally caducous sporangia with short pedicels, terminal and intercalary chlamydospores, and were mating type A2. The species isolated from trees in the Campania Region was identified as P.citricola. Isolates were homothallic, produced semipapillate, persistent, obclavate to obpyriform sporangia, occasionally with two apices, and antheridia paragynous. Identifications were confirmed by comparing restriction fragment length polymorphism patterns of the internal transcribed spacer region of rDNA with those obtained from previously identified species of Phytophthora. Pathogenicity of two isolates each of P. citricola and P. nicotianae was tested on 2-year-old potted walnut seedlings. Inocula were prepared by inoculating sterilized millet seeds moistened with V8 broth with plugs of mycelium and incubated for 4 weeks at 20°C in the dark. Infested seeds were added to potting soil at a rate of 3% (wt/vol). One day later, pots were flooded for 48 h to promote sporulation. Ten noninoculated seedlings were used as the control. Symptoms were assessed 2 months after inoculation. Seedlings inoculated with P. nicotianae developed necrosis of feeder and lateral roots, but only limited infection of taproots. Seedlings inoculated with P. citricola developed necroses at the insertion points of lateral roots. All four isolates produced visible damage to lateral roots on inoculated plants. P. nicotianae and P. citricola were reisolated from respectively infected roots. Results from these inoculations confirmed P. nicotianae and P. citricola as root pathogens of English walnut. Both species were associated with walnut decline as reported in the United States (3). To our knowledge, this is the first report of P. nicotianae and P. citricola on J. regia in Europe. References: (1) A. Belisario et al. Petria 11:149. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) M. E. Matheron and S. M. Mircetich. Phytopathology 75:977, 1985. (4) A. M. Vettraino et al. Plant Dis. 86:328, 2002.

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First Report of Cytospora punicae Causing Wood Canker and Branch Dieback of Pomegranate (Punica granatum) in the United States

Plant Disease ◽

10.1094/pdis-11-13-1133-pdn ◽

2014 ◽

Vol 98 (6) ◽

pp. 853-853 ◽

Cited By ~ 5

Author(s):

F. Peduto Hand ◽

R. A. Choudhury ◽

W. D. Gubler

Keyword(s):

United States ◽

Elongation Factor ◽

Punica Granatum ◽

The United States ◽

Internal Transcribed Spacer Region ◽

Intermittent Light ◽

First Report ◽

Consensus Sequences ◽

Vascular Discoloration ◽

Branch Dieback

Pomegranates (Punica granatum L.) are an expanding industry in the United States with California growing approximately 32,000 acres with a crop value of over $155 million (1). During June and July of 2012, we observed severe limb and branch dieback in pomegranate orchards cv. Wonderful located in Contra Costa, Kings, and Kern counties of California. Disease symptoms included yellowing of leaves, branch and limb dieback, wood lesions, and canker formation. Dark brown Cytospora-like cultures were consistently isolated from active cankers on potato dextrose agar (PDA) amended with 100 mg l−1 tetracycline hydrochloride. Three isolates (UCCE1223, UCCE1233, and UCCE1234) representative of each orchard were sub-cultured onto PDA and incubated at 22°C under fluorescent intermittent light (12 h light, 12 h dark). Fungal colonies had whitish mycelia that turned olive green to dark brown with maturity and formed globose and dark brown pycnidia after 12 days. Conidia were hyaline, aseptate, allantoid, and (4) 4.5 to 5 (6) × (1) 1.5 (2) μm (n = 180). Pycnidia formed in culture measured (250) 350 to 475 (650) μm in diameter (n = 40). Identification of the isolates was confirmed by sequence comparison of the internal transcribed spacer region (ITS1-5.8S-ITS2) of the rDNA and part of the translation elongation factor 1-α gene (EF1-α) with sequences available in GenBank. Consensus sequences of both genes of all isolates showed 99% homology to the species Cytospora punicae Sacc. (2). All sequences were deposited in GenBank (Accession Nos. KJ621684 to 89). Pathogenicity of the isolates was determined by branch inoculation. In December 2012, 3-year-old branches of P. granatum cv. Wonderful were inoculated by placing 5-mm-diameter mycelium plugs from the growing margin of 14-day-old PDA cultures in fresh wounds made with a 5-mm-diameter cork-borer. Eight branches per isolate were inoculated on eight different trees. Eight control branches were inoculated with non-colonized PDA agar plugs. Inoculations were covered with Vaseline and wrapped with Parafilm to retain moisture. Branches were harvested in August 2013 and examined for canker development and the extent of vascular discoloration spreading downward and upward from the inoculation point. Isolations from the edge of discolored tissue were conducted to fulfill Koch's postulates. C. punicae was re-isolated from 100% of the inoculated branches. Total length of vascular discoloration averaged 30.2 mm in branches inoculated with the three C. punicae isolates and 9 mm in the control branches. No fungi were isolated from the slightly discolored tissue of the controls. To our knowledge, this is the first report of C. punicae as a fungal trunk pathogen of pomegranate trees in the United States. References: (1) California County Agricultural Commissioners' Data, 2010 Crop Year. USDA NASS California field office, retrieved from http://www.nass.usda.gov/Statistics_by_State/California/ Publications/AgComm/201010cactb00.pdf , 2011. (2) P. A. Saccardo. Sylloge Fungorum 3:256, 1884.

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First Report of Grapevine Cankers Caused by Lasiodiplodia crassispora and Neofusicoccum mediterraneum in California

Plant Disease ◽

10.1094/pdis-94-6-0785b ◽

2010 ◽

Vol 94 (6) ◽

pp. 785-785 ◽

Cited By ~ 10

Author(s):

J. R. Úrbez-Torres ◽

F. Peduto ◽

W. D. Gubler

Keyword(s):

Dna Sequences ◽

Vascular Tissue ◽

Elongation Factor ◽

Fungal Culture ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Consensus Sequences ◽

Fast Growing ◽

Agar Plug ◽

Vascular Discoloration

Several species in the Botryosphaeriaceae family cause perennial cankers in the vascular tissue of grapevines and are responsible for the disease known as bot canker in California (3). Tissue from grapevine vascular cankers from samples submitted to our laboratory in the summer of 2009 were plated onto potato dextrose agar (PDA) amended with 0.01% tetracycline hydrochloride. Lasiodiplodia crassispora (Burgess & Barber) and Neofusicoccum mediterraneum (Crous, M.J. Wingf. & A.J.L. Phillips) were identified based on morphological and cultural characters as well as analyses of nucleotide sequences. L. crassispora isolates were characterized by a fast-growing, white mycelium that turned dark olivaceous with age on PDA. Conidia from pycnidia formed in cultures were thick walled and pigmented with one septum and vertical striations when mature. Conidia measured (25.8–) 27.5 to 30.5 (–33.4) × (12.1) 14.3 to 16.8 (–18.2) μm (n = 60). Pycnidia contained septate paraphyses. N. mediterraneum was characterized as having moderately fast-growing, light green mycelia on PDA. Pycnidia formation was induced with pine needles placed on 2% water agar. Conidia from pycnidia were hyaline, ellipsoidal, thin walled, unicellular, and measured (18.2–) 20.5 to 27.8 (–29) × (5.1) 5.9 to 6.5 (–7.2) μm (n = 60). DNA sequences of the internal transcribed spacer region (ITS1-5.8S-ITS2), part of the β-tubulin gene (BT2), and part of the translation elongation factor 1-α gene (EF1-α) from L. crassispora (UCD23Co, UCD24Co, and UCD27Co) and N. mediterraneum (UCD695SJ, UCD719SJ, UCD720SJ, UCD749St, and UCD796St) grapevine isolates from California were amplified and sequenced. Consensus sequences from L. crassispora and N. mediterraneum from California showed 99 to 100% homology with L. crassispora and N. mediterraneum isolates previously identified and deposited in GenBank (1,2). Sequences from the examined DNA regions of all isolates were deposited at GenBank (GU799450 to GU799457 and GU799473 to GU799488). Pathogenicity tests using three isolates per species were conducted on detached dormant canes of cv. Red Globe. Ten canes per isolate were inoculated by placing a 7-day-old 5-mm-diameter agar plug from each fungal culture into a wound made with a drill on the internode (4). Twenty shoots were inoculated with noncolonized PDA plugs for negative controls. Six weeks after inoculations, necrosis was measured from the point of inoculation in both directions. One-way analysis of variance was performed to assess differences in the extent of vascular discoloration and means were compared using Tukey's test. L. crassispora isolates caused an average necrotic length of 21.1 mm, which was significantly lower (P < 0.05) than the average necrotic length of 35.6 mm caused by the N. mediterraneum isolates. Reisolation of L. crassispora and N. mediterraneum from necrotic tissue was 100% for each species. The extent of vascular discoloration in infected canes was significantly greater (P < 0.05) than in control inoculations (8 mm) from which no fungi were reisolated from the slightly discolored tissue. To our knowledge, this is the first report of L. crassispora and N. mediterraneum as pathogens of Vitis vinifera and as a cause of grapevine cankers in California. References: (1) T. I. Burgess et al. Mycologia 98:423, 2006. (2) P. W. Crous et al. Fungal Planet. No. 19, 2007. (3) J. R. Úrbez-Torres and W. D. Gubler. Plant Dis. 93:584, 2009. (4) J. R. Úrbez-Torres et al. Am. J. Enol. Vitic. 60:497, 2009.

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First Report of Calosphaeria pulchella Causing Canker and Branch Dieback of Sweet Cherry Trees in Spain

Plant Disease ◽

10.1094/pdis-01-14-0027-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 1008-1008 ◽

Cited By ~ 2

Author(s):

M. Berbegal ◽

J. García-Jiménez ◽

J. Armengol

Keyword(s):

Sweet Cherry ◽

Prunus Avium ◽

South Australia ◽

Economic Loss ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Agar Plug ◽

Query Coverage ◽

Vascular Discoloration ◽

Cherry Trees

In autumn 2012, severe branch cankers and diebacks of sweet cherry trees (Prunus avium L.) were observed in orchards located in two different growing areas in Alicante Province (eastern Spain). In affected trees, leaves become dried without defoliation. Sectorial wood necrosis was also observed, occasionally associated with swollen bark and gum exudates. Isolations were made from diseased branches by surface-disinfecting small fragments of symptomatic tissue in 0.5% NaOCl, double-rinsing in sterile water, and plating them onto potato dextrose agar (PDA) amended with 0.5 g liter−1 of streptomycin sulfate. Plates were incubated at 25°C in the dark for 10 days, and all colonies were transferred to PDA. Pink to red colonies with white margins were consistently isolated. All isolates produced hyaline, allantoid to oblong-ellipsoidal conidia, 4 to 6 × 1.5 to 2 μm. The fungus was identified as Calosphaeria pulchella (Pers.: Fr.) J. Schröt (anamorph Calosphaeriophora pulchella Réblová, L. Mostert, W. Gams & Crous) based on morphology (1). Identification of C. pulchella isolates was confirmed by sequence comparison in GenBank database using the internal transcribed spacer region (ITS1-5.8S-ITS2) of the rDNA. Sequences showed 100% identity and 100% query coverage with C. pulchella reference isolate CBS 115999 (EU367451) (2). The ITS sequence of one of the isolates obtained in this study was deposited into GenBank (KJ396346). Two-year-old sweet cherry trees cv. Burlat were inoculated with two representative C. pulchella isolates from different orchards (1701 and 1702). A 5-mm cork borer was used to remove bark, and an agar plug from the growing margin of 20-day-old colonies was placed directly into the fresh wound, mycelium side down. Five trees were inoculated per isolate (five branches per tree) and 25 control branches were inoculated with non-colonized agar plugs. Inoculated tissue was covered with Vaseline and Parafilm to avoid the loss of water. Branches were taken to the laboratory 9 months after inoculation and thoroughly examined for canker development. The length of vascular discoloration was evaluated in each branch and resulting data were statistically analyzed. Length of vascular discoloration on the inoculated branches (6.6 ± 0.7) was significantly longer than in control plants (2.3 ± 0.3) at P < 0.001. Perithecia were neither observed on the artificially inoculated branches nor in the diseased sweet cherry trees from the sampled orchards. C. pulchella was re-isolated from the inoculated branches and no fungi were isolated from discolored tissue of the controls, confirming Koch's postulates. Canker of sweet cherry caused by C. pulchella is responsible for reducing yields and tree longevity in California and South Australia (3). Cultivated area of sweet cherry in Spain is around 25,000 ha. Hence, the potential economic loss from this pathogen could be substantial if left unchecked. To our knowledge, this is the first report of C. pulchella as a pathogen of sweet cherry trees in Spain. References: (1) M. E. Barr. Mycologia 77:549, 1985. (2) U. Damm et al. Persoonia 20:39, 2008. (3) F. P. Trouillas et al. Plant Dis. 96:648, 2012.

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First Report of Diplodia mutila Causing Branch Dieback of English Walnut cv. Chandler in the Maule Region, Chile

Plant Disease ◽

10.1094/pdis-11-17-1860-pdn ◽

2018 ◽

Vol 102 (7) ◽

pp. 1451 ◽

Cited By ~ 5

Author(s):

G. A. Díaz ◽

B. A. Latorre ◽

E. Ferrada ◽

M. Gutiérrez ◽

F. Bravo ◽

...

Keyword(s):

First Report ◽

English Walnut ◽

Branch Dieback

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First Report of Walnut Canker Caused by Fusarium incarnatum from India

Plant Disease ◽

10.1094/pdis-04-11-0352 ◽

2011 ◽

Vol 95 (12) ◽

pp. 1587-1587

Author(s):

B. Singh ◽

C. S. Kalha ◽

V. K. Razdan ◽

V. S. Verma

Keyword(s):

Fusarium Species ◽

Juglans Regia ◽

Infected Plant ◽

Distilled Water ◽

Conidial Suspension ◽

State University ◽

Single Spore ◽

Jammu And Kashmir ◽

First Report ◽

Branch Dieback

While screening newly introduced cultivars of walnut (Juglans regia) at Bhaderwah (Mini Kashmir), Jammu and Kashmir, India in September 2008, 60% of grafted plants were found to be dying because of a cankerous growth observed on seedling stems. Later, these symptoms extended to lateral branches. In the surveyed nurseries, cvs. SKU 0002 and Opex Dachaubaria were severely affected by the disease. Cankers were also observed in all walnut nurseries in the area with several wild seedlings also being observed to be exhibiting similar cankerous symptoms on stem and branches. Necrotic lesions from cankerous tissues on seedling stems were surface disinfested with 0.4% NaOCl for 1 min and these disinfected cankerous tissues were grown on potato dextrose agar (potato-250 g, dextrose-15 g, agar-15 g, distilled water-1 liter). A Fusarium sp. was isolated consistently from these cankerous tissues, which was purified using single-spore culture. Carnation leaf agar was used for further culture identification (2,3). The fungal colony was floccose, powdery white to rosy in appearance when kept for 7 days at 25 ± 2°C. Macroconidia were straight to slightly curved, four to eight septate and 30 to 35 × 3.5 to 5.7 μm. These are characteristics consistent with Fusarium incarnatum (3). Pathogenicity was confirmed by spraying a conidial suspension (1 × 106 conidia/ml) onto bruised branches of 1-year-old walnut plants (cv. Opex Dachaubaria) while sterile distilled water sprays were used for the controls. Inoculated plants were incubated at 20 ± 2°C and 85% relative humidity for 48 h. Fifty days following inoculation, branch dieback followed by canker symptoms developed on inoculated plants. Control plants remained healthy with no symptoms of canker. F. incarnatum (Roberge) Sacc. was repeatedly isolated from inoculated walnut plants, thus satisfying Koch's postulates. Infected plant material has been deposited at Herbarium Crytogamae Indiae Orientalis (ITCC-6874-07), New Delhi. To our knowledge, this is the first report of walnut canker caused by F. incarnatum (Roberge) Sacc. from India. This fungus was previously reported to be affecting walnut in Italy (1) and Argentina (4). References: (1) A. Belisario et al. Informatore Agrario 21:51, 1999. (2) J. C. Gilman. A Manual of Soil Fungi. The Iowa State University Press, Ames, 1959. (3) P. E. Nelson et al. Fusarium Species. An Illustrated Manual for Identification. The Pennsylvania State University Press, University Park, 1983. (4) S. Seta et al. Plant Pathol. 53:248, 2004.

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First Report of Botryosphaeria obtusa as Causal Agent of Olive Tree Branch Dieback in Tunisia

Plant Disease ◽

10.1094/pdis-01-12-0026-pdn ◽

2012 ◽

Vol 96 (6) ◽

pp. 905-905 ◽

Cited By ~ 4

Author(s):

M. Chattaoui ◽

A. Rhouma ◽

M. Msallem ◽

M. Pérez ◽

J. Moral ◽

...

Keyword(s):

Sodium Hypochlorite ◽

Olive Tree ◽

Fruit Rot ◽

Fluorescent Light ◽

Internal Transcribed Spacer Region ◽

Canker Disease ◽

First Report ◽

Botryosphaeria Obtusa ◽

Olive Trees ◽

Branch Dieback

A branch dieback of olive trees (Olea europaea L. cv. Manzanilla de Sevilla) was observed in 2010 in an orchard (50 ha), located in the Testour region of northern Tunisia. More than 50% of trees were severely damaged by the disease. Symptomatic trees presented dead branches and wilted leaves, which remained attached to the shoots, and the affected tissues appeared abnormally dark compared with the inner bark of healthy branches. Numerous pycnidia were observed on the surface of the infected branches. For diagnosis, symptomatic stems were collected and small pieces of discolored tissues were excised from lesion margins, surface sterilized in 0.5% sodium hypochlorite for 1 min, rinsed and dried on sterilized filter paper, then placed on acidified Difco potato dextrose agar plates (APDA; 2.5 ml of 25% lactic acid per liter). Plates were incubated at 25°C for 4 to 5 days, and hyphal tips from developing fungal colonies were transferred to PDA and placed under fluorescent light (12 h/day). A fastgrowing, pycnidia-producing fungus was consistently isolated, with conidia exuding onto the agar surface of 10-day-old cultures. On the basis of colony characteristics, isolates were identified as Botryosphaeria obtusa (3). Conidia were large, dark brown, aseptate, rounded at both ends or truncate at base, and 25 to 26.8 × 10.5 to 12.03 μm. Pathogenicity tests were performed on detached stems of cv. Manzanilla by 7-mm diameter mycelial plugs cut from actively growing cultures of the fungus. Stems (30 cm length) were cleaned, surface sterilized with sodium hypochlorite (0.25% for 2 min), and wounded with a sterilized scalpel. Mycelial disks were placed over wounds and wrapped with Parafilm to prevent desiccation. Control stems were mock inoculated with sterile agar plugs. Inoculated and control stems were placed in polyethylene boxes and incubated at 25°C. After 45 days, inoculated stems developed brown discoloration, and small dark pycnidia appeared on stem surfaces. Controls remained healthy. Koch's postulates were verified by isolating the fungus from symptomatic stems. To confirm the identification, DNA of one isolate was extracted and the fungal primers ITS1 and ITS4 (4) were used to amplify the internal transcribed spacer region of rDNA. Purified amplicons were sequenced and a BLAST search of the GenBank database revealed 99% homology with B. obtusa isolate HO166525.1. The anamorph of the fungus, Diplodia seriata, has been recognized as the cause of fruit rot of olive (1) and branch canker or dieback (2). To our knowledge, this is the first report of a canker disease of olive trees caused by B. obtusa in Tunisia. References: (1) J. Moral et al. Plant Dis. 92:311, 2008. (2) J. Moral et al. Phytopathology 100:1340, 2010. (3) A. Taylor et al. Australas. Plant Pathol. 34:187, 2005. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

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First report of Neofusicoccum parvum causing branch dieback on Juglans regia in Turkey

Journal of Plant Pathology ◽

10.1007/s42161-020-00662-8 ◽

2020 ◽

Author(s):

Merve Kara ◽

Emine Mine Soylu ◽

Soner Soylu ◽

Aysun Uysal ◽

Şener Kurt

Keyword(s):

Juglans Regia ◽

Neofusicoccum Parvum ◽

First Report ◽

Branch Dieback

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First Report of Alternaria alternata and Fusarium spp. Causing Brown Apical Necrosis in Walnut Fruit in Southern Chile

Plant Health Progress ◽

10.1094/php-05-21-0080-br ◽

2021 ◽

Author(s):

Ernesto Antonio Moya-Elizondo ◽

María Jose Lagos ◽

Juan G. San Martín ◽

Braulio E. Ruiz

Keyword(s):

Alternaria Alternata ◽

Fungal Pathogens ◽

Juglans Regia ◽

Bacterial Pathogen ◽

Southern Chile ◽

Fusarium Spp ◽

First Report ◽

Fruit Drop ◽

English Walnut ◽

Apical Necrosis

This is the first report of Alternaria alternata and Fusarium spp. causing brown apical necrosis (BAN) in walnut fruit in southern Chile. English walnut (Juglans regia L.) is the second most widely grown fruit in Chile. The bacterial pathogen Xanthomonas arboricola pv. juglandis affects walnut production in Chile and has been associated with apical necrosis symptom and premature fruit drop; this research focused on determining if fungal pathogens were associated with this damage. The presence of BAN in commercial walnut orchards in southern Chile reveals the need for improved phytosanitary programs to control this disease.

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