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Posts Tagged ‘Coconut’

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Accepted for publication
http://dx.doi.org/10.1094/PDIS-09-14-0891-PDN

http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-09-14-0891-PDN?ai=vgt&ui=1s1o&af=T&
Coconuts (Cocos nucifera) are an important tropical economic crop in Hainan and are used to enhance aesthetics of coastal areas. In April 2012, a new leaf blight disease of coconut was discovered in Wenchang, Hainan Province. The symptoms appeared on young and mature leaves of coconut. Initially, dark brown irregular spots surrounded by a yellow halo appeared on the leaf margins. As the disease progressed, the spots enlarged to thin and grayish-white lesions with brown margins. Black, minute, protuberant acervuli could be observed on both sides of the lesions. The lesions coalesced on each leaflet and spread to the entire leaf, leading to shriveling and defoliation. A survey of coconut gardens in Hainan indicated, led to a high incidence of recovery for the fungus Pestalotiopsis menezesiana, which can lead to premature defoliation, which would in turn, reduce vigor of support branches leading to early fruit drop. A total of 6 identical fungal isolates were obtained from coconut leaf lesions. The colony of the fungus on potato dextrose agar (PDA) medium was white, and cottony with smooth margin with a honey yellow colony reverse. The fungus produced acervuli on PDA medium, which were ink black, drop-shaped, and became dry after 40 days. Conidia were fusiform, slightly curved or straight, 5-celled, constricted at the septa, and 19-25.9×5.7-7.8 ųm (av. 23.4×6.7 ųm). The three median cells of conidia were pigmented, thick-walled, 14.8-19.5 ųm (av. 16.6 ųm) in length. The two upper cells were amber and the lowest cell was light-brown. The apical cell was hyaline with two or three cellar appendages arising at the apex. Appendages were hyaline, filiform, unbranched, nearly straight, and 13-23 ųm (av. 18.8 ųm) long. The basal cell had a single, hyaline, simple appendage, 4.1-6.9 ųm (av. 5.1 ųm) in length. The morphological characteristics of the fungus matched those of Pestalotiopsis menezesiana (1,2). For molecular identification, the ITS (internal transcribed spacer) region was amplified with primers ITS1 and ITS4, and the PCR product was sequenced (Genbank accession No.KJ605161). A BLASTn analysis demonstrated a 99% similarity with P. menezesiana (Genbank accession No. AY687302.1). 30 homologus strains in the Genbank were downloaded and a molecular phylogenetic tree was constructed. The result revealed that the closest relationship to the pathogen was with P. menezesiana. A pathogenicity test was established following Koch’s postulates. Ten 1.5-year-old coconut seedlings with four leaves per seedling were examined. Two leaves of every seedling were wounded-inoculated with a 2.7×105 spores﹒mL-1 suspension of conidia. Six leaves of three seedlings were wound-inoculated with sterile water as control. The seedlings were kept in greenhouse at 25°C for 10 days. Inoculated leaves showed typical symptoms matched those described above. The control leaves inoculated with sterile water did not show any symptoms. To our knowledge, P. palmarum was reported causing diseases of coconut palm in Tamil Nadu (3), but this was the first report of P. menezesiana on coconut in Hainan, China.

 

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See video on coconut rhinoceros beetles:

http://www.hawaiinewsnow.com/story/25386036/troubling-new-developments-in-the-war-against-an-invasive-pest

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Troubling new developments unfold in war against invasive pest

Posted: Apr 30, 2014 2:06 AM CDT
Updated: Apr 30, 2014 4:05 AM CDT
By Chelsea Davis

HONOLULU (HawaiiNewsNow) –
Coconut Rhinoceros Beetles (CRB) have been captured in new areas around O’ahu.

The latest detection was Tuesday afternoon at Ke’ehi Lagoon Park.

So are we losing the war against them?

The battle against the CRB began right before Christmas.

Now it has spread from Joint Base Pearl Harbor-Hickam to other areas outside the base.

They’re a threat to an iconic image of Hawaii because the tiny pests have a voracious appetite for palm trees.

“The adult beetle will bore into the crowns of coconut trees and if enough damage is done to the coconut tree, it can actually kill the tree,” said Darcy Oishi, Hawaii State Plant Quarantine Manager.

Efforts to eradicate the pests are increasing.

In fact, traps have popped up all around the island.

Between April 12th and April 25th, surveyors found 26 adults beetles. All but two were at Joint Base Pearl Harbor-Hickam. One was found at Iroquois Point, the other at Ke’ehi Lagoon Park.

“That number of detections since we started the program is actually an indicator that we’re doing a pretty good job on containing the problem,” Oishi said.

The origin of the Rhino beetle still remains a mystery.

Oishi says trying to control population and eventually eradicate the pests is priority.

“This is gonna be a long project, it’s gonna be a three year project once we eliminate all the breeding sights that we know of to monitor and make sure there are no beetles,” he said.

State quarantine officials say it’s too early to say if the beetles are here to stay.

If you see the beetle or traps that have fallen, you are asked to call the pest hotline at (808) 643-PEST.

 

 

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Mature coconut palm displaying mid-stage foliar discoloration symptoms indicative of coconut lethal yellowing disease.

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For complete article see: http://www.ndrs.org.uk/article.php?id=029012

New Disease Reports (2014) 29, 12. [http://dx.doi.org/10.5197/j.2044-0588.2014.029.012] Get pdf (819 KB)
First report of lethal yellowing disease associated with subgroup 16SrIV-A phytoplasmas in Antigua, West Indies
W.A. Myrie1*, N.A. Harrison2, L. Douglas1, E. Helmick2, J. Gore-Francis3, C. Oropeza4 and W.A. McLaughlin5

1 Coconut Industry Board, 18 Waterloo Road, Kingston 10, Jamaica W.I.
2 Plant Pathology, University of Florida, 3205 College Avenue, Ft Lauderdale Research and Education Center, Davie, FL 33314, USA
3 Ministry of Agriculture, Lands, Marine Resource & Agro Industry, The Plant Protection Unit, Queen Elizabeth Highway, P.O. Box 1282, St. John’s Antigua
4 Centro de Investigación Científica de Yucatán, A.C., Merida, Mexico
5 University of the West Indies, Mona Campus, Kingston 7, Jamaica, W.I

*cocomax@cwjamaica.com

Received: 02 Dec 2013; Published: 14 Apr 2014

Keywords: Coconut, queen palm, Bismarck palm, royal palm, foxtail palm
Coconut (Cocos nucifera) is an important perennial crop. Lethal yellowing (LY), a phytoplasma-associated disease, has been devastating coconut production in parts of the Caribbean. Local officials in Antigua observed widespread mortality of palms due to an unknown disease. Coconut palm, Christmas palm (Adonidia merrillii) Chinese fan palm (Livistona chinensis), edible date palm (Phoenix dactylifera), and Fiji fan palm (Pritchardia pacifica) were most affected. This new development followed previous reports of palm mortality due to LY in St Kitts (Myrie et al., 2012), an island in the West Indies with no prior history of the disease.

The present study was undertaken to ascertain whether widespread losses of palms currently under way in Antigua is a result of recent spread of LY disease to the island. Dead and declining coconut palms with foliar symptoms suggestive of LY disease (Fig. 1) were identified at several locations throughout Antigua. Twenty-nine palms exhibiting decline (Table 1) were sampled, DNA extracted (Myrie et al., 2012) and assessed for infection by group 16SrIV phytoplasmas. Five trunk tissues from coconuts and a queen palm (Syagrus romanzoffiana) tested positive (20.7% of the sampled palms) for infection by group 16SrIV phytoplasmas by primary PCR using primer pair P1 (Deng & Hiruki, 1991) and P7 (Smart et al., 1996) and in nested PCR using group 16SrIV-specific primer pair LY16Sf2/LY16-23Sr2 (Harrison et al., 2008). Palms were reassessed by group 16SrIV-specific real-time PCR using primers 503LY16S-ANYF/503LY16S-ANYR and TaqMan® probe 503LY16S-ANYM (Myrie et al., 2011) and with positive results in 20 palms (69%) including at least one representative of six palm species. Also, Bismarck palm (Bismarckia, royal palm (Roystonea regia) and foxtail palm (Wodyetia bifurcata), that had no prior history of susceptibility to LY, were infected. Nested PCR rDNA products (1.64 kb) in RFLP analysis produced fragment patterns that were indistinguishable (Fig. 2), but could be differentiated from Texas Phoenix palm decline phytoplasma, representative of 16SrIV-D.

Pairwise comparison between rDNA sequences (1.64 kb) derived from all six phytoplasma positive palms by nested PCRs yielded sequences that shared 99.9-100% identity with each other and 99-100% identity with comparable length rDNA sequences of phytoplasmas associated with coconut palms in St. Kitts (GenBank Accession No. JX0700937) and Jamaica (HQ613873). Representative sequences from coconut (AN6, AN28) and from S. romanzoffiana (AN21) were archived in GenBank (Accession Nos. JX560529, JX560530 and JX560531, respectively). Analysis of F2n/R2 portion of all six sequences using the Phyclassifier program (Zhao et al., 2009), confirmed the group and subgroup affiliations of Antiguan palm-associated phytoplasmas as members of group 16SrIV, subgroup A. A phylogenetic tree constructed from 16S rDNA sequences confirmed that all six phytoplasma strains examined clustered with other subgroup16SrIV-A strains belonging to the coconut lethal yellows phytoplasma subclade (Fig. 3). This report will be used to inform the Antiguan authorities as to the spread of lethal yellowing disease, which will help in the establishment of phytosanitary measures.

 

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