Plant Disease (PLANT DIS)

Publications in this journal

• Article: Temperature-Sensitive Resistance to Wheat streak mosaic virus in CO960333 and KS06HW79 Wheat

  D.L. Seifers, T.J. Martin, S. Haber
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  ABSTRACT: Temperature-sensitive resistance (TSR) that can protect against losses to Wheat streak mosaic virus (WSMV) has been described in elite wheat germplasm. A TSR identified in the advanced breeding line CO960333 and its derivative KS06HW79 was examined in growth-chamber tests conducted under constant temperature regimes of 18, 21, and 24°C against an array of WSMV isolates. At 18°C, all tested isolates systemically infected the pedigree parents, while the progeny line CO960333 remained free of symptoms; at 24°C, all lines were susceptible. At the intermediate temperature of 21°C, the TSR of KS06HW79 was effective in contrast to the TSRs of KS03HW12 and ‘RonL’. In field trials conducted in 2011 and 2012, the TSR expressed in KS06HW79 conferred complete protection against yield losses from inoculation with the Sidney 81 isolate of WSMV, while the TSR of RonL conferred similar protection in 2012 but allowed small losses in 2011. The resistance expressed by KS06HW79 is likely not due to the Wsm1 gene because it did not contain the tightly linked J15 sequence-characterized amplified region (SCAR) DNA marker. These findings suggest that KS06HW79 could be an additional TSR source of value to wheat-breeding programs seeking to control losses from WSMV.
  Plant Disease 07/2013; 97(7):983.
• Article: Pathogenicity of Diatrypaceous Fungi on Grapevines in Australia

  Pitt WM, Trouillas FP, Gubler WD, Savocchia S, Sosnowski MR
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  ABSTRACT: In addition to Eutypa lata, which causes Eutypa dieback, numerous other fungi in the Diatrypaceae family have been isolated from diseased grapevines (Vitis vinifera) and other woody hosts. Pathogenicity trials comprising 70 strains of diatrypaceous fungi representing nine species in six genera were conducted to determine whether these fungi, collected in Australia, were pathogenic to grapevines. When inoculated into wounded trunks of ‘Cabernet Sauvignon’, eight species, including E. lata, E. leptoplaca, Cryptovalsa ampelina, C. rabenhorstii, Eutypella citricola, E. microtheca, Diatrypella vulgaris, and a Diatrype sp. produced necrotic lesions significantly longer than on controls. In addition, all nine species (including a Cryptosphaeria sp.) were reisolated from the margins of developing lesions and at varying distances above and below the point of inoculation. Diatrypaceous fungi were frequently isolated from asymptomatic or otherwise healthy tissue several centimeters ahead of the disease margin. Methods to control diseases associated with diatrypaceous fungi must take into account their propensity to colonize woody tissues ahead of or in the absence of visible symptoms. Current recommendations for the management of Eutypa dieback using remedial surgery and pruning wound protection appear sufficient for the control of the other diatrypaceous fungi included in this study.
  Plant Disease 05/2013; 97:749-756.
• Article: Field resistance to Verticillium wilt in selected olive cultivars grown in two naturally infested soils

  C. Trapero, N. Serrano, O. Arquero, A. Trapero, F. J. López-Escudero
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  ABSTRACT: The resistance of 11 olive cultivars to Verticillium dahliae was assessed in two experimental field trials. One-year-old rooted olive cuttings from the World Olive Germplasm Bank (IFAPA research center, Córdoba, Spain) were planted in a heavily infested field in Utrera (Sevilla province) and in a moderately infested field in Andújar (Jaén province) of southern Spain. Plants were assessed for Verticillium wilt resistance during 22 months based on disease severity and tree growth. Severe disease symptoms were observed 6 months after planting in both trials. Twenty months after planting in the heavily infested soil, V. dahliae had killed nearly all of the trees of ‘Bodoquera’, ‘Cornicabra’, ‘Manzanilla de Sevilla’, and ‘Picual’, demonstrating the elevated risk of planting susceptible cultivars in a soil heavily infested with V. dahliae. ‘Arbequina’, ‘Koroneiki’, ‘Sevillenca’, and especially ‘Frantoio’, ‘Empeltre’, and ‘Changlot Real’ showed a high level of disease resistance. However, all of them were affected by the disease. Although the field results confirmed the level of resistance previously obtained for these olive genotypes under controlled conditions, there were some discrepancies. This information will be useful in managing the disease and also in selecting new cultivars for the breeding of Verticillium wilt resistance.
  Plant Disease 05/2013; 97(5):668-674.
• Article: First report of Johnsongrass mosaic virus (JGMV) infecting Pennisetum purpureum in Brazil

  Karina Nascimento Silva, Cícero Nicolini, Marilia Santos Silva, Celso Dornelas Fernandes, Tatsuya Nagata, Renato de Oliveira Resende
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  ABSTRACT: Tropical grass and legume species used as pasture grasses for cattle feeding cover over 25% of the agricultural area in Brazil. In the last years, plants showing virus-like symptoms have been observed in the main pasture grass growing areas. Plants of Pennisetum purpureum line CNPGL 00211 showing typical virus mosaic symptoms on leaves and growth reduction were collected in Bahia State, Brazil. Flexuous elongated potyvirus-like particles were observed in the leaf-dip preparation of diseased plants by electron microscopy. In addition, the virus was mechanically transmitted using a standard procedure for potyviruses (3) and produced similar symptoms in inoculated P. purpureum plants. For further molecular identification, total RNA was extracted from frozen symptomatic leaves following the guanidine thiocyanate method (1). cDNA synthesis was performed using oligonucleotide, OligodT50M10 and PCR was carried out using Potyvirus degenerate primers PY11 (5’- GGN AAY AAY AGY GGN CAR CC -3’) (2) and M10 (5’-AAG CAG TGT TAT CAA CGC AGA-3’). The amplified fragments of the expected size (approximately 2 Kb comprising part of the NIb protein gene, the entire coat protein (CP) gene and the 3’ nontranslated region) were separated using agarose gel electrophoresis, excised, and cloned into plasmid vector pGEMT-Easy (Promega) according to the manufacturer's instructions. Four selected clones were sequenced (Macrogen, South Korea). The sequenced 2.0-kb fragment (GenBank Accession No. KC333416) was compared with sequences available in GenBank and the highest nucleotide identity of 79% was observed with Johnsongrass mosaic virus (JGMV) isolated in Australia (3). According to the Potyvirus species demarcation convention based on CP identity (4), the virus isolate from P. purpureum belongs to the JGMV species. However, the amino acid sequence of the N-terminus of the CP of the Bahia isolate is distinct from JGMV sequences reported in GenBank. The phylogenetic analysis of the CP confirmed the difference since this Bahia isolate was located in a clearly distinct branch separate from all JGMV isolates. This is the first report of a JGMV in Brazil infecting tropical grass in the main pasture areas.
  Plant Disease 04/2013;
• Article: Induction and maintenance of systemic acquired resistance by acibenzolar-S-methyl in three cultivated tobacco types

  Charles Johnson, Venkat Parkunan, Liaosa Xu, Yiming Peng, Sue Ann Tolin, Jonathan Eisenback
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  ABSTRACT: Induction and maintenance of systemic acquired resistance (SAR) in ‘N’ gene containing burley, flue-cured, and oriental tobacco cultivars were assessed by monitoring decreases in the number of local lesions caused by Tobacco mosaic virus (TMV) following treatment with acibenzolar-S-methyl (ASM). Leaf samples were collected from lower, middle, and top positions on seedlings at 3 day intervals over 21 days, following ASM treatment and subsequent inoculation with TMV under laboratory conditions. Local lesion number for each leaf was recorded 7 days post-inoculation. Reductions in TMV local lesion numbers on ASM-treated vs. nontreated tobacco varied over time, and differed for each tobacco type. Based on reduced local lesion numbers, SAR was induced in burley and flue-cured tobacco by 3 and 6 days post-inoculation, respectively, while oriental tobacco responded by 9 days. SAR was maintained in burley tobacco from 3 to 9 days after ASM application, and from 9 to 15 days after application in oriental tobacco. ASM treatment reduced local lesion numbers in flue-cured tobacco significantly at 6, 12, and 21 days post-application, but not at 15 and 18 days after treatment. The SAR response was similar among lower, middle, and top leaves with no effect of ASM on response by leaf position, although TMV local lesion numbers were greater on lower leaves than middle and top leaves 6 days after treatment, but significantly less on lower leaves 18 days after treatment compared to middle and top leaves.
  Plant Disease 04/2013;
• Article: First Report of Orobanche purpurea on Achillea wilhelmsii in Iran

  A. R. Yousefi, K. Jamshidi, M. Oveisi, H. Karimojeni, M. Pouryosef Page
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  ABSTRACT: Achillea wilhelmsii C. Koch (Asteraceae) is a wild herb widely disturbed in Iran and known locally as yarrow. This plant is an important medicinal plant and it has been used for its analgesic, antiphlogistic, antispasmodic, and antibacterial effects in Iranian folk medicine. Field surveys revealed infestations of yarrow broomrape, Orobanche purpurea Jacq., on A. wilhelmsii plants in two locations in province of Zanjan (Zanjan, 36°37′19.85″ N, 48°27′16.87″ E, 1,707.4 m elevation, and Qolabar, 36°19′19.85″ N, 48°19′16.41″ E, 1,663.9 m elevation) in northwestern Iran in May 2012. The annual mean air temperature and the average maximum and minimum air temperatures were 11, 18, and 4°C, respectively. The annual mean precipitation was 298 mm. The infestation of A. wilhelmsii was confirmed by verifying the attachment of the yarrow broomrape to the A. wilhelmsii roots. Broomrape plant heights were between 24 and 37 cm. The stems were erect, unbranched, slender, and swollen near the base at contact with host, 0.5 to 10 mm diameter. The leaves were reduced to scale or bracts up to 10 to 15 mm long. The flowers were in dense terminal spikes, usually restricted to the top third or half of the shoot. There was one bract and two bracteoles surrounding each flower. The bracts measured 7 to 10 mm, had ovate lanceolates shorter than the calyces, and lanceolate bracteoles were 5 to 10 mm. The calyces were gamosepalous, entire, and whitish. Corollas were 13 to 18 mm long, and were dull bluish-purple with dark veins, suffused with whitish-yellow at the base. The upper part was slightly curved forwards. Stamens were epipetalous, inserted 4 to 7 mm above the corolla base, with filaments glabrous. The anthers were glabrous along sutures. Stigma lobes were white. Fruit was an oval capsule, 0.9 to 10 mm. Botanists at the College of Agriculture of Zanjan University confirmed the identity of O. purpurea. A. millefolium has been reported as a host plant for yarrow broomrape (1,2). However, to our knowledge, this is the first report of yarrow broomrape on A. wilhelmsii in Iran. Since production and farming of A. wilhelmsii as a medicinal plant has recently started on a commercial scale in Iran, the parasite weed could pose a serious threat to production of this plant.
  Plant Disease 04/2013; 97(5):694.
• Article: First Report of Neofusicoccum australe and N. luteum Associated with Canker and Dieback of Quercus robur in Portugal

  Carla Barrada, António Correia, Artur Alves
  Plant Disease 04/2013; 97(4):560.
• Article: First Report of Knot Disease Caused by Pseudomonas savastanoi on Sweet Olive in Central Italy

  T. Cinelli, D. Rizzo, G. Marchi, G. Surico
  Plant Disease 03/2013; 97(3):419.
• Article: Evaluation of resistance to powdery mildew in triticale seedlings and adult plants

  Troch V, Audenaert K, Vanheule A, Bekaert B, Höfte M, Haesaert G
  Plant Disease 03/2013;
• Article: Dramatic Change in Citrus tristeza virus Populations in the Dominican Republic

  Luis A. Matos, Mark E. Hilf, Xiomara A. Cayetano, Andrea O. Feliz, Scott J. Harper, and Svetlana Y. Folimonova
  Plant Disease 02/2013; 97(3):339-345.
• Article: Viruses and virus diseases of Rubus.

  Martin R.R, MacFarlene S, Sabanadzovic S, Quito-Avila D.F, Tzanetakis I.E, Bindu Poudel
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  ABSTRACT: Blackberry and raspberry are members of the family Rosaceae. They are classified in the genus Rubus, which comprises hundreds of species and has a center of origin in the Far East. Rubus is divided into 15 subgenera with blackberries classified in the Rubus (formerly Eubatus) and raspberries in the Idaeobatus subgenera. Rubus species are propagated vegetatively and are subject to infection by viruses during development, propagation, and fruit production stages. Reports of initial detection and symptoms of more than 30 viruses, virus-like diseases, and phytoplasmas affecting Rubus spp. were reviewed more than 20 years ago. Since the last review on Rubus viruses, significant progress has been made in the molecular characterization of many of the viruses that infect Rubus spp. Currently, reverse transcription–polymerase chain reaction detection methods are available for most of the viruses known to infect Rubus. The goals of this article are to update the knowledge on previously characterized viruses of Rubus, highlight recently described viruses, review the virus-induced symptoms, describe the advances made in their detection, and discuss our knowledge about several virus complexes that cause serious diseases in Rubus. Virus complexes have been identified recently as the major cause of diseases in blackberries and raspberries.
  Plant Disease 02/2013; 97:168-182.
• Article: Pathogenicity and host–parasite relationships of Heterodera cruciferae in cabbage.

  Sasanelli, Vovlas, Trisciuzzi, Cantalapiedra-Navarrete, Palomares-Rius, J. E, Castillo
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  ABSTRACT: Stunted cabbage (‘Lupini’) associated with severe soil infestations by a cyst-forming nematode were observed in large patches of open fields in Castellaneta, province of Taranto, southern Italy. Morphological traits based on mature cysts, males, and second-stage juveniles (J2s) and molecular analysis of ribosomal DNA (D2 to D3 expansion segments of 28S and internal transcribed spacer [ITS]1 region) were used to identify the species. ITS1 sequence information supported the identity of Heterodera cruciferae, also showing a high degree of similarity to other species of the Heterodera Goettingiana group, including H. goettingiana, H. carotae, and H. urticae. Nematodes successfully established permanent feeding sites in cabbage roots which caused cellular alterations in the root cortex, endodermis, pericycle, and vascular cylinder by inducing typical multinucleate syncytia. Syncytial cytoplasm was granular and dense, with variously sized vacuoles and hypertrophied nuclei with nucleoli. Cabbage plant growth was also reduced in pathogenicity tests. The relationship between the initial nematode population density in soil and shoot plant weight was well described by the Seinhorst’s equation. Tolerance limits with respect to shoot plant weight of cabbage to H. cruciferae was estimated as 1.50 units of eggs plus J2s/cm3 of soil. The minimum relative value (m) for plant height was 0.71 at an initial nematode population density of (Pi) ≥ 64 units of eggs plus J2s/cm3 of soil. The maximum nematode reproduction rate (Pf/Pi) was 4.6 times that of the initial population density of 8 units of eggs plus J2s/cm3 of soil.
  Plant Disease 02/2013; 97(3):333-338.
• Article: First report of tomato pith necrosis caused by Pseudomonas mediterranea in the US and P. corrugata in Ohio

  Dr. Xiulan Xu, Dr. Fulya Baysal-Gurel, Dr. Sally Ann Miller
  Plant Disease 01/2013;