Botryosphaeriaceae species causing canker and dieback of English walnut ( Juglans regia ) in Italy

2020 ◽  
Vol 51 (1) ◽  
Author(s):  
Giorgio Gusella ◽  
Selene Giambra ◽  
Gaetano Conigliaro ◽  
Santella Burruano ◽  
Giancarlo Polizzi
Keyword(s):  
Juglans Regia ◽  
English Walnut ◽  
Botryosphaeriaceae Species

OPTIMIZING SECONDARY SOMATIC EMBRYO PRODUCTION IN ENGLISH WALNUT (Juglans regia L.)

2001 ◽  
pp. 187-194 ◽  
Author(s):  
H. Tang ◽  
Z. Ren ◽  
G. Reustle ◽  
G. Krczal
Keyword(s):  
Somatic Embryo ◽  
Juglans Regia ◽  
Embryo Production ◽  
Secondary Somatic Embryo ◽  
English Walnut ◽  
Somatic Embryo Production

JUGLANS REGIA L. (JUGLANDACEAE) — English Walnut, Carpathian or Persian Walnut

2017 ◽  
pp. 194-197
Author(s):  
James A. Duke
Keyword(s):  
Juglans Regia ◽  
Persian Walnut ◽  
English Walnut

A PCR based SNPs marker for specific characterization of English walnut (Juglans regia L.) cultivars

2010 ◽  
Vol 38 (2) ◽  
pp. 1237-1249 ◽  
Author(s):  
Loredana F. Ciarmiello ◽  
Pasquale Piccirillo ◽  
Giovanni Pontecorvo ◽  
Antonio De Luca ◽  
Ioannis Kafantaris ◽  
...  
Keyword(s):  
Juglans Regia ◽  
English Walnut

Identification and cloning of a complementary DNA encoding a vicilin-like proprotein, Jug r 2, from English walnut kernel (Juglans regia), a major food allergen☆☆☆★★★

1999 ◽  
Vol 104 (6) ◽  
pp. 1311-1320 ◽  
Author(s):  
Suzanne S. Teuber ◽  
Koren C. Jarvis ◽  
Abhaya M. Dandekar ◽  
W.Rich Peterson ◽  
Aftab A. Ansari
Keyword(s):  
Food Allergen ◽  
Juglans Regia ◽  
Dna Encoding ◽  
Complementary Dna ◽  
Major Food ◽  
English Walnut

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

Plant Disease ◽  
2003 ◽  
Vol 87 (3) ◽  
pp. 315-315 ◽  
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.

scholarly journals Characterization of Oomycete Species Associated With Root and Crown Rot of English Walnut in Chile

Plant Disease ◽  
2019 ◽  
Vol 103 (4) ◽  
pp. 691-696 ◽  
Author(s):  
Jeannette Guajardo ◽  
Sebastián Saa ◽  
Natalia Riquelme ◽  
Gregory Browne ◽  
Cristian Youlton ◽  
...  
Keyword(s):  
Phytophthora Cinnamomi ◽  
Juglans Regia ◽  
Pythium Ultimum ◽  
Crown Rot ◽  
Root Rots ◽  
Root And Crown Rot ◽  
Pathogenicity Tests ◽  
English Walnut ◽  
Crown And Root Rot ◽  
Root Tissues

English (Persian) walnut (Juglans regia) trees affected by root and crown rot were surveyed in five regions of central Chile between 2015 and 2017. In each region, nine orchards, ranging from 1 to 21 years old, were randomly selected and inspected for incidence and severity of tree decline associated with crown and root rot. Soil and symptomatic crown and root tissues were collected and cultured in P5ARP semiselective medium to isolate potential oomycete pathogens, which were identified through morphology and molecularly using ITS sequences in the rDNA gene and beta tubulin gene. The most frequently isolated species was Phytophthora cinnamomi. Pathogenicity tests were conducted with representative oomycete isolates. P. cinnamomi, P. citrophthora, and Pythium ultimum were all pathogenic in J. regia. Nevertheless, only P. cinnamomi and P. citrophthora were pathogenic to English walnut. Py. ultimum caused limited levels of root damage to English walnut seedlings. Our research indicates that as the Chilean walnut industry has expanded, so have walnut crown and root rots induced by oomycetes.

scholarly journals (111) Evaluation of the Salt Tolerance of Walnut Rootstocks

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1040A-1040
Author(s):  
Janet Caprile ◽  
Steve Grattan
Keyword(s):  
Salt Tolerance ◽  
Block Design ◽  
Juglans Regia ◽  
Salt Transport ◽  
Graft Union ◽  
High Incidence ◽  
Randomized Complete Block Design ◽  
High Boron ◽  
English Walnut ◽  
B Uptake

In areas of California with a high incidence of walnut blackline disease, walnut orchards are increasingly being planted on English walnut (Juglans regia) rootstocks that are tolerant to the virus. There is limited documentation on the salt tolerance of this rootstock. This work was done to quantify the response of English walnut rootstocks to high boron (B), chloride (Cl), and sodium (Na) and to compare this to the more common rootstocks, Northern California Black (J.hindsii) and Paradox (J. hindsii × J. regia). The trial was configured as a randomized complete-block design with 20 plots. Plots consisted of three proximate, matched `Chandler' trees, each on a different rootstock. Leaf samples over a 2-year period showed that trees on the English rootstock had a significantly higher salt uptake than trees on Paradox, which had a significantly higher uptake than trees on Black. Bark cores showed little difference in B uptake between any of the rootstocks. Bark cores also showed that all rootstocks accumulated significantly more B than the scion portion of the tree, indicating that B transport may be limited by the graft union. Trees on English rootstock had significantly more B in the scion bark cores than trees on either Black or Paradox, indicating that rootstocks with a J. hindsii parent may be better at reducing salt transport across the graft union.

Pistil late flower differentiation in English walnut (Juglans regia L.): A developmental basis for heterodichogamy

1985 ◽  
Vol 26 (4) ◽  
pp. 333-338 ◽  
Author(s):  
Vito S. Polito ◽  
Nai-Yan Li
Keyword(s):  
Juglans Regia ◽  
English Walnut

scholarly journals Variation among Persian Walnuts in Response to Inoculation with Xanthomonas campestris pv. juglandis

1992 ◽  
Vol 117 (3) ◽  
pp. 527-531 ◽  
Author(s):  
Keith E. Woeste ◽  
Gale H. McGranahan ◽  
M.N. Schroth
Keyword(s):  
Xanthomonas Campestris ◽  
Juglans Regia ◽  
Crop Loss ◽  
English Walnut ◽  
Walnut Blight ◽  
Apparent Resistance

Walnut blight of English walnut (Juglans regia L.), incited by Xanthomonas campestris pv. juglandis (Pierce) Dowson, causes significant crop loss in California. To assess levels of resistance in walnut germplasm, leaves and nuts of mature walnut genotypes were inoculated with X. campestris pv. juglandis. Significant differences were found among cultivars in size and frequency of lesions on leaves and in frequency of abscission of diseased leaves. Cultivars also varied in frequency of abscission of nuts following infection and in marketability of infected nuts. Afthough there was considerable variation in disease levels over 2 years, leaves of PI 159568 consistently received significantly higher disease ratings than leaves of `Chandler' or `Adams'. Nuts of `Adams', `Payne', PI 18256, and `Sinensis 5' abscised less frequently following inoculation than nuts of other cultivars. In addition, the quality of infected nuts that did not abscise was consistently better for PI 18256 and `Sinensis 5'. The rank of cultivars for levels of disease in inoculated leaves was not significantly correlated with the rank of cultivars for frequency of infestation of dormant buds associated with infected foliage. The apparent resistance of walnut germplasm may be affected by the abscission or necrosis of infected tissues.

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