#Candidatus Liberibacter

[unicornheadnebula]

Citrus Greening in Florida - What's Going On With The Oranges?

Q: What is citrus greening? How it has effected the citrus trees in Florida. Citrus Greening, also known as Huanglongbing (HLB), is a devastating disease affecting citrus trees. It’s caused by a bacterium named Candidatus Liberibacter. This bacterium is spread primarily by a tiny insect called the Asian citrus psyllid. Once a tree is infected, there’s currently no cure for the…

[indizombie]

According to Cristina Davis, a professor of mechanical and aerospace engineering at the University of California, who has been working for years to build instruments that can detect volatile organic compounds, that is a possibility. She explains that if, for example, there are 50 volatile compounds emitted by each different Xylella-infected plant species, it could be that a portion of those compounds are shared between all. "I think that there's a really reasonable expectation that you could train an animal like a dog or a sensor to be able to detect that over time," Davis says. In fact, in 2014, Davis and her team managed to use an advanced instrument, a differential mobility spectrometer, to spot citrus plants infected by the bacteria Candidatus Liberibacter.

Agostino Petroni, ‘The plan to save Italy's dying olive trees with dogs’, BBC

[entomoblog]

Deux espèces d'insectes de la famille des Psyllidae proches des pucerons et inféodées aux agrumes transmettent une maladie qui affecte les plantations d'orangers

See on Scoop.it - Les Colocs du jardin

La maladie du HLB, transmise par des insectes, ravage les plantations d'orangers. En Floride, le secteur de l'agrumiculture s'est effondré. Au Brésil, 56 millions d'arbres ont été arrachés en vingt ans. En Espagne et au Portugal, les premiers "hyménoptères suceurs-piqueurs" [sic] sont apparus. Malgré de vastes programmes de recherche, aucun remède totalement efficace contre ce fléau n'a été trouvé. Seule la lutte biologique semble donner des résultats.

  La culture des oranges en danger

Loïc Chauveau, 23.11.2024

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NDÉ

Complément

  "La maladie du dragon jaune (黃龍病 Huánglóngbìng en chinois, HLB) ou verdissement des agrumes et plus rarement maladie des pousses jaunes est une maladie bactérienne mortelle des agrumes. Elle est répandue en Asie, en Afrique, et désormais aussi en Amérique Tropicale et subtropicale. L'agent pathogène bactérien est transmis par des insectes vecteurs.

  Cette maladie a été décrite pour la première fois en 1929 et signalée pour la première fois en Chine en 1943. La variante africaine a été signalée pour la première fois en 1947 en Afrique du Sud, où elle est encore très répandue. Les premiers symptômes de la maladie ont été observés en 2004 dans des vergers d’agrumes au Brésil. La maladie s'est depuis fortement répandue au Brésil, dans plusieurs autres états d'Amérique du Sud et d'Amérique Centrale, dans les Caraïbes, et aux États-Unis, notamment en Floride et en Californie.

  Les agents pathogènes sont des bactéries mobiles du genre Candidatus Liberibacter spp. Ces bactéries sont transmises par deux espèces d'insectes de la famille des Psyllidae proches des pucerons et inféodés aux agrumes : le psylle asiatique des agrumes, Diaphorina citri et, en Afrique, par le psylle africain des agrumes, Trioza erytreae."

  Maladie du dragon jaune — Wikipédia, version du 29 octobre 2024 à 15:47 https://fr.wikipedia.org/wiki/Maladie_du_dragon_jaune

  Bernadette Cassel's insight:

  'psylle' in Les Colocs du jardin https://www.scoop.it/topic/les-colocs-du-jardin?tag=psylle

  'maladie du dragon jaune' in EntomoNews https://www.scoop.it/topic/entomonews/?&tag=maladie+du+dragon+jaune

  'Diaphorina citri' in EntomoNews https://www.scoop.it/topic/entomonews/?&tag=Diaphorina+citri

[agroemdia]

Greening requer monitoramento contínuo

"A primeira etapa de controle ao inseto vetor, segundo informações do Fundo de Defesa da Citricultura (Fundecitrus), inicia antes do plantio das mudas"

Fernando Bonafé Sei* O início do verão é uma data muito importante para os produtores de citros. É nessa época do ano que os produtores devem fazer a segunda etapa do controle do psilídeo para pomares de 0 a 3 anos de idade. O inseto é vetor da bactéria Candidatus Liberibacter spp., que causa o greening (huanglongbing/HLB), uma das doenças mais prejudiciais para a citricultura e que pode…

[elcultivodelapatata]

En el próximo número de la revista "Tierras" saldrá un artículo en el que hablo de las "Amenazas fitosanitarias actuales para el cultivo de la patata", en el que analizo la situación, en lo que afecta a España, de las plagas y enfermedades de la patata que, desde mi punto de vista, suponen una amenaza a nivel mundial. Las que he considerado son:

Virus Y de la patata (PVY)

Gusano de alambre (Agriotes spp)

Polilla guatemalteca (Tecia solanivora, Scrobipalpopsis solanivora)

Pulguilla de la patata (Epitrix spp)

Punta morada, zebra chips (Candidatus Liberibacter solanacearum)

[newswireml]

Nutrient uptake in citrus rootstock affected by huanglongbing#Nutrient #uptake #citrus #rootstock #affected #huanglongbing

Credit: CC0 Public Domain Huanglongbing (HLB) is presumably caused by the phloem-limited bacteria, Candidatus Liberibacter asiaticus (CLas), and is one of the most devastating diseases of citrus. A distinctive chlorotic mottle on fully expanded leaves is one of the identifying symptoms of HLB. Currently, there is no cure for HLB, and there is no commercial HLB-resistant germplasm. However, it…

[lifetein]

Antimicrobial Peptides Show Promise for Combatting Citrus Greening

https://www.lifetein.com/blog/antimicrobial-peptides-show-promise-for-combatting-citrus-greening/ Citrus greening, or Huanglongbing (HLB), is a disease that devastates citrus production all over the world. The culprit behind HLB is the bacterium Candidatus Liberibacter spp. (e.g., CLas), an unculturable pathogen that has proven very difficult to treat. Once a tree is infected, it becomes unproductive and dies within years, costing the global citrus market billions. While current attempts to combat HLB rely on controlling the insect vector, scientists have turned some attention towards the potential of peptides. Their work displayed how antimicrobial peptides show promise for combatting citrus greening, mainly by methods against CLas itself. Antimicrobial peptides effective against CLas bacteria With not many current effective options to fight HLB, scientists believe the next area of area of interest was targeting the CLas secretory pathway using antimicrobial peptides provided by LifeTein. Specifically, the antimicrobial peptides would be blocking the TolC efflux pump protein. The study found three peptides capable of doing this by binding tightly with the TolC receptors, and even the β barrel entrance of the protein as well. Treatment with peptides in this manner showed effective inhibition and even mortality in models closely resembling CLas. The studies displayed using antimicrobial peptides show major promise for future treatment of HLB. With the chemical resistant bacteria CLas being nearly impossible to slow down, peptides just may have been holding the solution all along. There is hope that new therapies can be developed utilizing the strategies shown, and the global citrus production can rest easy after decades worth of HLB ravaging the farms. Wang, Haoqi, Nirmitee Mulgaonkar, Samavath Mallawarachchi, Manikandan Ramasamy, Carmen S. Padilla, Sonia Irigoyen, Gitta Coaker, Kranthi K. Mandadi, and Sandun Fernando. 2022. “Evaluation of Candidatus Liberibacter Asiaticus Efflux Pump Inhibition by Antimicrobial Peptides” Molecules 27, no. 24: 8729. https://doi.org/10.3390/molecules27248729

[symbiotic-science]

Citrus greening disease, or Huanglongbing (HLB), is deadly, incurable, and the most significant threat to the citrus industry. Most HLB research focuses on the tree canopy, but scientists in California studied the impact of HLB on root systems. They recently published the first study to report on the response of two different varieties of citrus to the causal bacterium, 'Candidatus Liberibacter asiaticus' using metabolomics and microbiome technologies.

"Metabolomics is a cutting-edge field of study that provides snapshot information about the metabolism of living things," explains author Emily M. T. Padhi, "while microbiome studies provide valuable information about the microbial communities living in a particular ecological niche—some microbes are beneficial to the host, while others can be harmful."

Padhi and colleagues wanted to see how the root system of two varieties of citrus responded to HLB. They collected roots from healthy and infected Lisbon lemon and Washington Navel orange trees grown in greenhouses at the same time and under the same conditions.

They found that both varieties experienced a reduction in root sugars and amino acids when exposed to HLB. However, they also found differences. While the concentration of malic acid and quinic acid (two metabolites involved in plant defense) increased in the navel roots, they decreased in the lemon roots. They also found that the beneficial bacteria Burkholderia increased substantially in navel plants but not in lemons, which contradicts previous studies...

[sciencespies]

Trained dogs are the most efficient way to hunt citrus industry's biggest threat

https://sciencespies.com/biology/trained-dogs-are-the-most-efficient-way-to-hunt-citrus-industrys-biggest-threat/

Trained dogs are the most efficient way to hunt citrus industry's biggest threat

This dog has been trained to detect citrus greening long before a citrus tree shows signs of infection Credit: Timothy R. Gottwald, ARS-USDA.

Dogs specially trained by Agriculture Research Service (ARS) scientists have proven to be the most efficient way to detect huanglongbing—also known as citrus greening—according to a paper just published in the Proceedings of the National Academy of Sciences.

Currently, the only solid hope of curtailing the spread of citrus greening is to eliminate trees with the disease as quickly as possible to prevent further spread. Early detection of the citrus greening pathogen is crucial because trees can be infected and act as a source to spread the disease months or years before showing symptoms that are detectable by the naked eye.

ARS plant epidemiologist Timothy R. Gottwald with the U.S. Horticultural Research Laboratory in Fort Pierce, Florida, discovered that dogs can be trained to sniff out the presence of Candidatus Liberibacter asiaticus, the bacteria that causes citrus greening, with greater than 99 percent accuracy.

“We found that, once trained, these dogs were able to identify infected trees within two weeks of the trees being inoculated,” Gottwald said. “The dogs also were able to distinguish the citrus greening pathogen from a variety of other citrus bacterial, viral, fungal, and spiroplasma pathogens, including closely related Liberibacter species.

During testing, the citrus greening detector dogs had total of 4 to 15 false negatives and false positives on 950 to 1,000 trees per dog. Occasionally, the dogs alerted on clean trees that were in the same spot where an inoculated tree had been placed in previous tests due to residual scent.

In contrast, the only currently USDA-approved method for confirming the presence of the citrus greening pathogen—a DNA-based assay called a polymerase chain reaction (PCR) test—detected less than 3 percent of infections at 2 months, 16 of 30 inoculated trees at 16 months, and 20 out of 30 in 17 months.

Trained dog detects citrus greening in an orchard long before sings of infections are present. Credit: Timothy R. Gottwald, ARS-USDA

PCR tests also require considerable time, financial and human resources for sampling, processing and laboratory work. They are very expensive to use as a general surveillance tool.

The training is similar to that of explosives sniffing dogs, in which the dogs are taught to recognize a particular odor and to sit down next to the source once found. The dogs are rewarded with play time with a toy. However training is more extensive and specific because the dogs are trained to detect a bacteria infecting a plant, and the two cannot be separated.

So far, Gottwald’s program has trained 19 dogs obtained from European breeders of detection canines because of their keen abilities and drive.

“When we ran epidemiological models, we found canine detection combined with infected tree removal would allow the citrus industry to remain economically sustainable over a 10-year period, compared to using molecular assays or visual inspection combined with tree removal, which failed to suppress the spread of infection,” Gottwald explained.

Citrus green sniffing dogs have been deployed for 9 months in California and northern Florida.

In the past decade, huanglongbing has caused more than 70 percent decline in the production of oranges for juice and the fresh fruit market in Florida and threatens other states, making it the largest economic threat to the $3.35 billion U.S. citrus industry. It was first found in the United States in 2005, citrus greening has spread to Florida, Texas, California, Georgia, and Louisiana.

Explore further

Greening devastates the citrus industry—new research offers a solution

More information: Timothy Gottwald el al., “Canine olfactory detection of a vectored phytobacterial pathogen, Liberibacter asiaticus, and integration with disease control,” PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.1914296117

Provided by United States Department of Agriculture

Citation: Trained dogs are the most efficient way to hunt citrus industry’s biggest threat (2020, February 3) retrieved 3 February 2020 from https://phys.org/news/2020-02-dogs-efficient-citrus-industry-biggest.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

#Biology

[fruitworldmedia]

What you need to know about the Citrus Disease

What you need to know about the Citrus Disease

Marie A. C. Langham South Dakota State University

In recent years, Florida’s $9 billion commercial citrus industry has been damaged by an outbreak of citrus canker (Fig. 1), caused by Xanthomonas axonopodis pv. citri. The industry has lost millions of dollars due to reduced citrus yields, undesirability of infected fruit, loss of markets for nursery stock, and removal of infected citrus trees.…

[cropforlife]

Secretion secrets revealed: Pathogen effector characterization for a devastating plant disease

Secretion secrets revealed: Pathogen effector characterization for a devastating plant disease

Sometimes the most niche plant pathogens pack the greatest punch. Such is the case for the Florida citrus industry, which has seen a 70% decline in its orange production since the introduction of Huanglongbing (citrus greening) in 2005. This disease is caused by the bacteria Candidatus Liberibacter asiaticus, which spreads via a flying insect — unlike most bacterial plant pathogens. When the…

[entomoblog]

Allons-nous vivre dans un monde sans agrumes ?

See on Scoop.it - EntomoNews

Une maladie, le Huanglongbing (HLB) est en train de dévaster les vergers de très nombreux pays, provoquant de très lourdes pertes de production d’agrumes.

  Publié: 6 août 2024, 10:07 EDT

Raphael Morillon, Cirad; Barbara Hufnagel, Cirad; Patrick Ollitrault, Cirad et Virginie Ravigné, Cirad

  [...]

Une bactérie transmise par des insectes

"La bactérie est transmise par deux insectes piqueurs-suceurs de la famille des psylles. Ces petits insectes ailés de 2 à 5 millimètres se nourrissent, comme les pucerons, en insérant leur rostre dans les plantes pour sucer la sève. Lorsqu’ils se nourrissent sur de très jeunes rameaux d’agrumes porteurs de la maladie du HLB, ils peuvent être contaminés par la bactérie, qui va se multiplier en eux, et qu’ils vont retransmettre à d’autres arbres, tout comme les moustiques transmettant les virus de la dengue ou du chikungunya. Ces deux espèces de psylles sont assez spécifiques des agrumes et d’espèces apparentées comme l’oranger jasmin (Murraya paniculata) souvent employé comme plante d’ornement.

L’efficacité de la transmission de la bactérie par les psylles est redoutable. Une seule piqûre peut suffire à transmettre la maladie.

  Le psylle asiatique (Diaphorina citri) d’origine tropicale et subtropicale a pour l’heure été observé en Asie, en Amérique du Sud, dans les Caraïbes, en Floride et en Californie. Le psylle africain (Trioza erytreae) est lui plus adapté aux conditions fraîches de certains plateaux africains.

  Pour l’heure, parmi les grandes zones agrumicoles mondiales, seuls le bassin méditerranéen et l’Australie ne sont pas infectés par la maladie. Toutefois, le psylle africain, même s’il n’est pas porteur de la maladie, est déjà bien implanté en Espagne et au Portugal depuis respectivement 2014 et 2015. Le psylle asiatique, qui est considéré comme le vecteur le plus efficace pour transmettre la bactérie, a été identifié en Israël en 2021. Plus récemment encore, durant l’été 2023, ce même insecte a été identifié pour la première fois dans l’espace européen à Chypre.

  On suspecte que ces mouvements à longue distance pourraient être liés aux échanges commerciaux de plants d’agrumes ou au transport par les voyageurs de plantes ornementales. Les températures plus chaudes associées au changement climatique pourraient aussi être favorables à l’adaptation de D. citri dans l’ensemble du bassin méditerranéen."

  [...]

  Image : Photographie du psylle asiatique. Fourni par l'auteur

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NDÉ

Précédemment

  → Le vecteur du HLB découvert pour la première fois en Europe - Hortimedia, 05.09.2023 https://hortimedia.ma/le-vecteur-du-hlb-decouvert-pour-la-premiere-fois-en-europe/

  → Agrumes : le psylle vecteur de la maladie du dragon jaune détecté en UE | Réussir fruits & légumes, 20.09.2023 https://www.reussir.fr/fruits-legumes/agrumes-le-psylle-vecteur-de-la-maladie-du-dragon-jaune-detecte-en-ue

  Insights into the origin of the invasive populations of Trioza erytreae in Europe using microsatellite markers and mtDNA barcoding approaches | Scientific Reports, 20.09.2021 https://www.nature.com/articles/s41598-021-97824-0

  Recent additions to EPPO A1 and A2 Lists https://www.eppo.int/ACTIVITIES/plant_quarantine/A1_A2_recent_add

  Pests recently added to the EPPO A1/A2 Lists or of urgent phytosanitary concern - Last updated in 2023-09

  Bacteria and phytoplasmas Date Main host plants Parts of the EPPO region at risk 'Candidatus Liberibacter africanus', L. asiaticus, L. americanus and their vectors (Citrus huanglongbing or greening) - Diaphorina citri - Trioza erytreae

A1 in 1984

A1 in 1975 A1 in 1975

Citrus Southern part of the EPPO region (citrus-growing areas)  

  European and Mediterranean Plant Protection Organization (EPPO) Organisation Européenne et Méditerranéenne pour la Protection des Plantes (OEPP)

[elcultivodelapatata]

Ayer se inspeccionó el campo de postcontrol nacional de Villagutiérrez - Burgos- Castilla y León - España y hoy se ha inspeccionado el otro campo de postcontrol nacional de patata de siembra que se hace en Gauna - Álava - País Vasco - España.

En este caso se han inspeccionado 51 lotes de patata de siembra en precontrol y 206 lotes en postcontrol.

Estos postcontroles que hacemos no tienen nada que ver con la certificación de la patata de siembra, porque se hacen a posteriori y lo que se pretrende con ellos, es comprobar que, entre otros, los análisis de ELISA que se hacen antes de la certificación de la patata de siembra, funcionan.

Antes de certificar un lote se analiza la tierra para ver que está libre de nematodo del quiste (Globodera rostochiensis y Globodera pallida), se analizan los virus por ELISA, se analiza cada lote para detección de Ralstonia solanacearum, Clavibacter sepedonicus y Candidatus Liberibacter solanacearum. En el momento de la plantación del postcontrol se registran para cada lote, los tubérculos podridos. Posteriormente se registran las plantas nacidas (% de nascencia), y en esta inspección de ayer y hoy se registra para cada lote: raquíticas, PVY, PLRV, otros virus, rizoctonia, pie negro y mezclas de otras variedades.

Al igual que ayer, la inspección se ha realizado en muy buenas condiciones, porque también ha estado cubierto de nubes el cielo.