Archive for the ‘Plant Pathogens’ Category


Watch out for bacterial leaf blight disease, farmers told

The Hindu Bureau TIRUCHI, DECEMBER 11, 2021 18:34 ISTUPDATED: DECEMBER 13, 2021 09:47 IST

Paddy crop with symptoms of bacterial leaf blight disease in a field near Pullampadi in Tiruchi district.  

It has been found in standing paddy crop in some parts of Tiruchi district

With sporadic incidence of bacterial leaf blight disease in the standing samba and thaladi paddy crop in a few parts of the district, the Agriculture Department has advised farmers to take up appropriate measures to check its spread if symptoms appear in their fields.

Samba and thaladi paddy crop has been raised on about 49,000 hectares in the district. Due to the intermittent rains during the north-east monsoon and favourable climatic conditions, symptoms of bacterial leaf blight are appearing in the crop in some places. The bacterium enters through the cut wounds in the leaf tips and edges, becomes systemic and causes orange and yellow coloured wavy margins in the leaf tips and edges.

The disease symptoms first appear as small water-soaked translucent lesions on the edges of the leaf blade which later turn yellowish orange or brown, mostly confined to the edges of the leaf with wavy margins. As the disease progresses, the yellowish orange or brown lesions cover the entire leaf blade which may turn straw coloured .This will affect the photosynthesis of the plant, thereby reducing the yield.

For easy diagnosis, the leaf blade of the plant can be cut and dipped in water. If affected, white bacterial ooze could be noticed making the water turbid. Further, the bacterial infestation could lead to secondary infestation of the fungal pathogens which causes fungal diseases in the later stage of the crop.

Clipping of the tip of the seedling at the time of transplanting, heavy rain or dew, flooding, deep irrigation water, severe wind and application of excessive nitrogen, especially late top dressing are some of the favourable conditions for the spread of the disease.

If the disease is in the initial stage, 20% cow dung extract can be sprayed twice at 15 days interval. To control developed symptoms, 120 grams of streptomycin sulphate and tetracycline hydrochloride combination along with 500 grams of copper oxychloride mixed in 200 litres of water should be sprayed per acre. The spraying should be repeated 15 days later.

Farmers could contact the officials at the nearest Agricultural Extension Centres for more details and appropriate advice, Agriculture officials said.

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Seed microorganisms override soil microorganisms when colonizing plants

by American Phytopathological Society

crop seed
Credit: CC0 Public Domain

New research shows that when it comes to colonizing plants, microorganisms from seeds have more staying power than microorganisms from the soil.

“Ever since I started working on plant microbiomes, I’ve been wondering about their origins,” explained Étienne Yergeau, a plant pathologist based at the INRS in Quebec, Canada. “Are they coming from the seeds and transmitted somehow by the mother plant or are they picked up from the environment?”

Yergeau and colleagues set out to explore these questions through soybeans. They grew soybean seeds under controlled conditions and selectively removed the microorganisms from the seeds or from the soil then let the plant develop.

“We found that when the seed microorganisms were not removed, they had precedence over the soil microorganisms to colonize all the plant parts, including the roots and the soil associated to the roots. It is only when we removed the seed microorganisms that the soil microorganisms could colonize the plant, and only the roots and the soil associated to the roots,” said Yergeau.

Previous studies had looked at the origin of the plant microbiome mostly by comparing the microorganisms found in and on the plant to the ones in seeds and soil, but without experimentally removing one or the other.

“Our ultimate goal is to find a way to modify the microbiomes of crops to increase yields, quality, and resistance to stresses and thereby reduce chemical inputs,” explained Yergeau. “Our research shows that the seed should be the primary target for such efforts. If we modify the seed microbiome, there is a good chance we will be able to generate plants with tailor-made beneficial microbiomes and head toward a more sustainable agriculture.”

Explore furtherSeeds transfer their microbes to the next generation

More information: Itumeleng Moroenyane et al, Soybean Microbiome Recovery after Disruption is Modulated by the Seed and Not the Soil Microbiome, Phytobiomes Journal (2021). DOI: 10.1094/PBIOMES-01-21-0008-RProvided by American Phytopathological Society

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Arriving in mainland Malaysia, banana Blood disease now poised to spread throughout Southeast Asia

by American Phytopathological Society

Arriving in mainland Malaysia, banana Blood disease now poised to spread throughout Southeast Asia
With Blood disease all of the Kepok banana fruit rot at the same time and are inedible. Credit: Jane Ray

The world’s most consumed fruit and an important staple for many developing companies, bananas are increasingly threated by Blood disease, so named because cut banana stems look like they are bleeding. Blood disease causes fruit rot, leaf wilt, and plant death. There is no known cure for the disease.

Banana Blood disease was first reported in Kayuadi Island in South Sulawesi, Indonesia in 1905 and so severely devastated the banana plantations that they were abandoned. The disease was contained to this small area for 60 years due to restrictions on movement of banana plant materials, but eventually it escaped.

In 1987, Blood disease was found in West Java and it spread rapidly across the Indonesian archipelago—it is now recorded in 25 of the 34 provinces. The disease was so brutal that many farmers were forced to abandon production. More recently the disease has made it to peninsular Malaysia, making it highly likely the disease will continue to spread to other Asian countries.

“Without intervention, the losses are likely to be devastating due to epidemics in areas where growers have no experience managing this disease,” explained Jane Ray, a Ph.D. student at the University of Queensland who is studying the biology and epidemiology of Blood disease. “I am determined to understand this disease and use this information to develop improved diseases management options, helping to reduce crop loss and mitigate the risk of spread to new areas, improving food security in the tropics.”

Ray and colleagues carefully reviewed multi-lingual literature in Dutch, Indonesian, and English to gather historical knowledge of the disease. They also conducted extensive surveys across the islands of Indonesia to validate the historical distribution data and determine the current geographic dispersal and pattern of spread of Blood disease.

Their study confirmed Blood disease in 18 different varieties of banana, including Cavendish, the world’s most popular variety of banana, and other members of the Musa genus. The study also found that varieties previously reported as unaffected by the disease are now included among reported infections.

“Greater clarity regarding modes of disease transmission is urgently required to develop effective disease management approaches as the rapid expansion of blood disease is an emerging threat to banana production in Southeast Asia,” said Ray. “Our study shows that all disease problems start small and can be contained if acted on early but if left unchecked and allowed to spread, they can become major constraints to production over large geographic areas.”

Explore furtherVideo: Why banana candy doesn’t taste like banana

More information: Jane D. Ray et al, Geographic Expansion of Banana Blood Disease in Southeast Asia, Plant Disease (2021). DOI: 10.1094/PDIS-01-21-0149-REProvided by American Phytopathological Society355 shares

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New focus on emerging viral diseases

November 09, 2021

A new Horizon 2020 project is underway to address viral diseases responsible for major crop losses in tomatoes and cucurbits in Europe and beyond. Called ‘VIRTIGATION – Emerging viral diseases in tomatoes and cucurbits: Implementation of mitigation strategies for durable disease management’, the project includes INRAE, one of ENDURE’s French partners, Germany’s Julius Kühn Institute (JKI) and Wageningen University (WU) and Stichting Wageningen Research (WR) from the Netherlands.

VIRTIGATION is running for four years (2021 to 2025) and is being coordinated by the Laboratory for Tropical Crop Improvement at the Department of Biosystems of KU Leuven (Belgium). In particular, it is seeking to develop short, medium and long-term solutions to whitefly-transmitted begomoviruses and mechanically transmitted tobamoviruses in tomato and cucurbit crops.

The project reports: “Every year, viral diseases wreak havoc on tomato and cucurbit crops worldwide, destroying in Europe alone billions of EUR in harvest. The EU-funded VIRTIGATION project is on a mission to combat this viral crop destruction and safeguard tomatoes and cucurbits.

“Viral diseases are not only affecting European fields and greenhouses: across the globe, from Morocco, Israel to India, tomatoes and cucurbits are vital staple crops that are under threat. Colossal losses in harvests have been reported, ranging from 15% to entire crop destruction. As the world needs to increase its food production by at least half by 2050 to feed a growing population, mitigating the devastating impact of plant diseases is essential to ensure sufficient food supply, both in quantity and quality.”

VIRTIGATION has set itself six specific objectives:

  • Knowledge sharing and engagement of stakeholders in research activities
  • Develop robust diagnostic tests, quarantine measures and identify ecological factors driving disease outbreaks
  • Understand plant-virus-vector interactions
  • Develop IPM solutions
  • Identify and pyramid natural resistance to viral diseases and vectors
  • Train the tomato and cucurbit value chains

INRAE will be involved in the research on viral genome sequencing and monitoring virus outbreaks, plant-virus-vector interactions and the spread of emerging viral diseases under climate change, and will also be the National Knowledge Broker for France in the project’s multi-actor approach.

JKI is the National Knowledge Broker for Germany and will mainly be involved in the “research on plant-virus-vector interactions and integrated virus and vector management, where it is exploring viral symptom determinants of ToBRFV (Tomato brown rugose fruit virus) to support the search for virus isolates that could be used in cross-protection strategies”.

WU will be contributing to the research on plant-virus-vector interactions and the spread of emerging viral diseases under climate change, with a focus on tomato-geminivirus-whitefly interactions, and finding tomato genes for resistance to ToBRFV.

WR’s departments of Plant Breeding and Biointeractions & Plant Health are contributing to all the project’s research work packages, “with a particular focus on virus epidemiology and ecology, as well as virus and vector control through breeding and Integrated Pest Management (IPM)”. WR is also the National Knowledge Broker for the Netherlands.

For more information:

Last update: 23/12/2021 – ENDURE © 2009 – 

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EuroBlight: Recommendations to combat disease

November 16, 2021

EuroBlight, a potato late blight network for Europe, celebrates 25 years of existence this year and has set out a series of recommendations to continue the work to combat the disease, which comes with a huge cost worldwide in terms of its control and crop losses.

The recommendations were produced following EuroBlight’s 18th workshop, ‘Fostering the sustainable management of early and late blight in potato’, which was held online earlier this year and attracted 120 participants. Reflecting EuroBlight’s support for other late blight networks around the world, the workshop included participants from Europe, South America, USA, Africa and India.

The recommendations are as follows (you can read the full text of the recommendations here):

Recommendation 1: Continue and renew efforts to monitor populations of blight pathogens, their evolution and their epidemiology

EuroBlight strongly believes a pan-European surveillance of populations of blight pathogens is essential for fast reaction to new emergences and optimization of control strategies. EuroBlight will maintain its efforts to serve as a pilot network for the production and use of population information in IPM, and would welcome national and EU support to fully implement it.

Recommendation 2: Assess, develop and integrate control methods into efficient, tailor-made local strategies through collaborative and participatory research

As a long-time actor in IPM, EuroBlight supported the search for as diverse an array of control options as possible, including biocontrol technologies, host resistance, crop/farm management alongside a set of high-performance fungicides. A strong focus must now be put on combining these components into efficient, robust, local and sustainable control strategies; this can only be achieved through multi-actor actions involving key stakeholders along the value chain.

Recommendation 3: Developing a transnational, distributed European infrastructure

Since its inception, EuroBlight acted as a pan-European network, developing initiatives for a coordinated response to the challenges of sustainable control of early and late blights. EuroBlight therefore strongly supports any initiative to establish a permanent infrastructure able to sustain and expand the collection, integration, use and dissemination of data relevant to IPM design and validation, as well as the capacity building in these fields.

Recommendation 4: Fostering global outreach, cooperation and harmonisation

Dealing with major diseases distributed worldwide, EuroBlight recognizes both the challenges and opportunities for a global approach of sustainable crop health management. It is also well aware of the need for increased visibility and accessibility of the data and knowledge gathered during its 25 years of existence. EuroBlight recommends that the long-term efforts to share and develop a global view of the blights issue, but also of the new questions it raises (local versus global management issues, rapid development of information technologies, impact of global warming on pathogen distribution and spread etc…) be fully exploited for the identification of research, development and priority setting, and for the set-up of transcontinental activities improving the lasting control of such major plant diseases.

For more information:

  • Visit the EuroBlight website here
  • Read the recommendations in full here

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New robot traps pests for 80 kms

The latest iteration of a pest and disease trapping robot has landed in the Adelaide Hills, ready to capture, identify and warn industry of any threats to horticulture farms and vineyards.

Deployed off the back of a trailer, the $170,000 Sentinel 7 features a high volume air sampler to collect airborne fungal spores, plus multiple suction traps that draw in insects within its immediate vicinity and migratory bugs from distances of up to 80kms with the help of wind currents.

Being delivered through Hort Innovation with 17 partner organisations as part of the $21M iMapPESTS initiative, the Sentinel 7 will proceed to Naracoorte South Australia after an 8-week stint in the Adelaide Hills.

Hort Innovation Head of Research and Development Byron de Kock said the development of the Sentinel 7 marks the culmination of more than two years of work by scientists in collaboration with growers.

“Exotic or unwanted plant pests put the nation’s $32B broadacre, horticulture and forestry industries at great risk,” he said. “Through this project, we have been able to create a purpose-built unit that has been refined through previous iterations and is mobile, easy to use and most importantly, really effective at detecting and trapping pests. The innovative device also boasts an automatic online dashboard that presents data to growers to review in real time.”

South Australian Research and Development Institute senior scientist, Dr Rohan Kimber, said that the launch of Sentinel 7 marks the evolution of a proof-of-concept idea about modernizing our approach to monitoring plant pests and diseases across Australia’s diverse growing regions.

“Sentinel 7 is a user-friendly, flexible and optimised mobile surveillance device that offers industry an opportunity to adapt to dynamic growing conditions and stay on the front foot of managing pests and diseases”.

Adelaide Hills vegetable grower Richard Cobbledick said the iMapPESTS sentinel work offers an exciting glimpse into what could be a future where managing pest threats is so much easier.

“I’m really keen to see how the information generated by these high-tech devices can be extended to a system where I get a ping on my phone with a warning or alert to look out for a particular pest or disease,” Mr Cobbledick said.

“I’m looking forward to seeing how the technology develops and delivers to industry.”

iMapPESTS is led by Hort Innovation, through funding from the Australian Government Department of Agriculture, Water and the Environment as part of its Rural R&D for Profit program, with contributions from fellow Rural Research and Development Corporations, State Governments, research and data agencies, and industry representative groups.

For more information:
Kelly Vorst-Parkes
Tel.: +61 0427 142 537
Email: kelly.vorst-parkes@horticulture.com.au

iMapPESTS website: imappests.com.au

Publication date: Wed 22 Dec 2021

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Robot delivers ‘world-first’ season free of powdery mildew sprays

16 December 2021 | by FarmingUK Team | Farm ProductsMachinery and EquipmentNewsProduceThorvald performs light treatment to control mildew on strawberries, reducing the need for fungicidesThorvald performs light treatment to control mildew on strawberries, reducing the need for fungicides    

An autonomous robot which reduces powdery mildew through light treatment achieved complete control of the pathogen during this growing season.

‘Thorvald’ delivered UV-C treatment to protect strawberry plants on over 10 hectares of land at Clock House Farm and Hugh Lowe Farm, both in Kent.

The robot performs light treatment to control mildew on strawberries and vines, drastically reducing the need for fungicides.

During March to October, the farms did not spray their crops with any powdery-mildew-targeting chemical control agent, with Thorvald’s team calling this a ‘world-first’.

The autonomous robot was developed by Saga Robotics and has been on trial in the UK since 2019.

But 2021 has proven to be a watershed year due to an especially prevalent pathogen. Despite this, plant samples were examined having no traces of the fungal disease.

Oli Pascall, managing director at Clock House Farm, described the work undertaken by Thorvald as an ‘industry leading result’.The autonomous robot was developed by Saga Robotics and has been on trial in the UK since 2019The autonomous robot was developed by Saga Robotics and has been on trial in the UK since 2019

“The first three robots that Saga Robotics used to treat crops delivered positive results in 2020, although there was evidence that we needed a stronger intensity of UV-C.

“This has been addressed with a positive outcome, and the improved results seen in 2021 are of an outstanding level of protection.”

Pål Johan, CEO of Saga Robotics, said this year’s results had only increased what was already a strong interest in their service.

“Throughout the season, our robots have efficiently treated over 7,300 linear kilometres of strawberries with completely effective treatment, 100% robot service reliability and no failures.”

Dan Sargent, head of plant sciences at Saga added: “Not a single chemical has been needed to protect these plants from powdery mildew all season.

“And that’s great news for the growers, their customers, and the consumers.”

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HLB can infect an entire tree weeks before symptoms become apparent

Brazilian scientists have been able to measure the speed of a bacterium that causes the incurable citrus greening disease (Huanglongbing). HLB is the most devastating citrus disease in the world. Afflicted trees grow yellow leaves and low-quality fruit and eventually stop producing altogether.

Silvio A. Lopes, a plant pathologist based at Fundecitrus, research institution maintained by citrus growers of the State of Sao Paulo in Brazil: “We found that CLas can move at average speed of 2.9 to 3.8 cm per day. At these speeds a tree that is 3 meters in height will be fully colonized by CLas in around 80 to 100 days, and this is faster than the symptoms appear, which generally takes at least 4 months.”

Lopes and colleagues also studied the impact of temperature on the speed of colonization. They already knew that CLas does not multiply well in hot or cold environments, but now they have more specific data.

“We estimated that 25.7°C (78°F) was the best condition for CLas to move from one side to the other side of the tree,” said Lopes. This is the first time impact of temperature on plant colonization of CLas has been experimentally demonstrated. “The grower can use this information to select areas less risky for planting citrus trees.”

Source: eurekalert.org

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LSU awarded $5 million to look into invasive species harmful to sweet potatoes

A team of LSU AgCenter researchers, collaborating with scientists from four other universities, have been awarded a USDA National Institute of Food and Agriculture grant of more than $5 million, aiding them in developing sweet potato varieties resistant to the invasive guava root-knot nematode.

The AgCenter team is spearheaded by nematologist Tristan Watson. It has also received a sub-grant for $990,000 to support research on sweet potato breeding and characterization of resistance mechanisms and associated genes as well as extension of research findings to regional and national stakeholders.

Watson: “Root-knot nematodes are particularly damaging to the sweet potato. The overall goal of this project is to provide Louisiana sweet potato growers effective tools for the management of established and emerging root-knot nematode species.”

Source: lsuagcenter.com

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Novel Plantibodies show promise to protect citrus from Greening Disease

Citrus greening [huanglongbing (HLB)] has emerged as the most significant disease in citrus (Citrus sp.) agriculture. The disease is associated with the Candidatus Liberibacter species of bacteria. The most prevalent and virulent species in this group is Candidatus Liberibacter asiaticus. It is primarily vectored by the Asian citrus psyllid [ACP (Diaphorina citri)]. 

The bacteria and insect vector are present in many citrus orchards worldwide, including the United States, China, and Brazil. HLB often has a devastating impact on infected citrus; causing a rapid decline, with loss of fruit yield and quality and potentially leading to tree death. The bacteria has had a significant negative impact on the citrus industry, causing loss of fruit quality and yield, as well as loss of root mass, leading to tree decline. Finding a cure has been challenging due to the complexity of the CLas bacteria interactions with the citrus host and the Asian citrus psyllid. Another factor that has made it hard to recover from the disease is the tendency of the citrus industry to focus on a small number of cultivars with commercially desirable traits, but little genetic diversity.

Researchers who are working to find a citrus cultivar that is HLB resistant have a choice of either adding genetic variation through breeding with distant relatives or modifying the trees transgenically. In an article published this month in the Journal of the American Society for Horticultural Science, scientists present promising results from transgenic populations that produce antibodies that can bind with CLas proteins and reduce the bacteria’s ability to replicate. 

This study advances the research needed to test the durability and strength of any resistance conferred by expression in rootstocks to a grafted tree and will hopefully lead to the development of a novel protection strategy for HLB.

According to Ed Stover, a Research Horticulturalist with the USDA Agricultural Research Service, “The Florida citrus industry desperately needs more HLB tolerant trees. If sufficient tolerance can be conferred by a single transgenic rootstock then it will greatly expedite implementation. Any transgenic solution will require extensive validation and analyses for non-target effects and food safety.” 

For more information: doi.org

Publication date: Wed 15 Dec 2021

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PestNet: Grahame Jackson posted a new submission ‘Bacteria and plants fight alike ‘


Bacteria and plants fight alike

Bacteria and plants fight alike

by Weizmann Institute of Science

by Weizmann Institute of Science
A brown blotch on a plant leaf may be a sign that the plant’s defenses are hard at work: When a plant is infected by a virus, fungus or bacterium, its immune response keeps the disease from spreading by killing the infected cell, as well as a few surrounding ones. A new study at the Weizmann Institute of Science points to the evolutionary origins of this plant immune mechanism. The study may help explain how major plant defenses work and how they may one day be strengthened to increase resilience against plant diseases that each year cause billions of dollars of crop losses worldwide.

About two years ago, scientists in the United States and Australia discovered that when a plant’s immune system kills infected cells to contain disease, this action involves a protein with a segment called TIR that produces a certain signal molecule. In a new study led by Prof. Rotem Sorek of Weizmann’s Molecular Genetics Department and Dr. Gal Ofir, then a graduate student, Sorek’s team has revealed that bacteria also use TIR as an immune mechanism, and that TIR achieves immunity in plants and bacteria in similar ways.

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