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Archive for the ‘Fungi’ Category

AUGUST 19, 2022

Microbes protect a leaf beetle—but for a price

by Daniel Fleiter, Max Planck Institute for Biology Tübingen

Microbes protect a leaf beetle - but for a price
Leaf Beetle. Credit: Max Planck Institute for Biology Tübingen

Insects are known to rely on microbial protection during immobile developmental stages, such as eggs. But despite the susceptibility of pupae to antagonistic challenges, the role of microbes in ensuring defense during an insect’s metamorphosis remained an open question. Scientists from Germany and Panama have now discovered a novel defensive partnership between a fungus and a leaf beetle. The microbe provides a protective layer around the beetle’s pupae and thus prevents predation. In exchange, the beetle disperses the fungus to its host plant, expanding its range. Now published in Current Biology, the researchers present the results of their study.

Antagonistic interactions are widespread in nature, spurring the evolution of protective traits. In insects, as with other animals, symbioses with beneficial microbes can serve as a source of defensive adaptations.

In their study, biologists from the Max Planck Institute for Biology in Tübingen, the University of Tübingen, both Germany, and the Smithsonian Tropical Research Institute, Panama, discovered a mutualistic partnership between the ascomycete Fusarium oxysporum and Chelymorpha alternans, a leaf beetle: The fungus protects the pupae of the leaf beetle against predators. And in exchange, the beetle disperses the fungus to its host plants and thus contributes to its transmission.

“The fungus retained a metabolic profile that reflects its dual lifestyle,” explains Hassan Salem, Research Group Leader at the Max Planck Institute for Biology and senior author of the study. “Our findings show a mutualism ensuring pupal protection for an herbivorous beetle on the one hand, in exchange for symbiont dissemination and propagation on the other hand,” Salem adds.

A microbial dimension to pupal defense

Previous research across numerous study systems described such partnerships with microbes and insects by examining eggs and other juvenile phases. But for the critical pupal stage, the role of microbial protection remained unexplored. And despite birds and some rodents posing threats to pupae, it is rather the smallest predators and parasitoids such as ground beetles, ants and wasps that pursue them in the wild.

“Structural and chemical adaptations are known to protect pupae against predators and other threats. But microbes appear to also play an important role when we consider how a beetle defends itself during metamorphosis,” comments Aileen Berasategui, an Early Career Researcher at the Cluster of Excellence “Controlling Microbes to Fight Infections” (CMFI), University of Tübingen and the first author of the study.

A protective microbial coat

The research team was driven by the observation that a dense microbial growth appears to form at the onset of pupation. Sequence- and culture-based approaches revealed this growth to be Fusarium oxysporum. To understand and demonstrate their hypothesis of a mutual partnership, the researchers performed field studies in Panama while they explored the survival rates of pupae with and without the protective fungus.

Based on follow up investigation using sweet potato plants, the research team further determined that the leaf beetle carries and distributes the fungus to uninfected plants. As the beetles carry the fungus on legs during the adult stage, this resulted in widespread infection of the plants.

The leaf beetle Chelymorpha alternans belongs to the speciose Cassidinae subfamily of leaf beetles. Many members of this group appear to carry the morphological features of the symbiosis with Fusarium oxysporum, the most conspicuous being the microbial coat that covers pupae. When the symbiosis evolved and how it is maintained are central questions that members of this international team hope to uncover.


Explore further

Whether horseradish flea beetles deter predators depends on their food plant and their life stage


More information: Aileen Berasategui et al, The leaf beetle Chelymorpha alternans propagates a plant pathogen in exchange for pupal protection, Current Biology (2022). DOI: 10.1016/j.cub.2022.07.065

Journal information: Current Biology 

Provided by Max Planck Institute for Biology Tübingen

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Corteva Agriscience8-05-22 AGRONOMY_PHOTOS_Corn_9923-lowres.jpg

Apply fungicide before Tar Spot finds a place in your corn field.

Corteva Agriscience | Aug 15, 2022

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Tar spot is top of mind for many Corn Belt farmers. Caused by the fungal pathogen Phyllachora maydis, tar spot reduces yield potential by affecting the photosynthetic capacity of leaves and causing rapid premature biological aging or leaf senescence.

Initial symptoms include small brown lesions that darken with age. Early signs of tar spot can be mistaken for insect feces. Tar spots (stroma) are embedded in leaf tissues and are often visible on the underside of the leaf. The texture of the leaf often becomes bumpy and uneven when the fruiting bodies are present. This foliar disease may be difficult to find if infections develop in patches in the middle of a field.

Related: Quick Take: Big Bud at FPS, new checkoff boards, field days

“Tar spot scouting begins with looking into the canopy and using the sun to look for shadows on the underside of the leaves,” said Kevin Fry, a Pioneer Field Agronomist in Pennsylvania.

Ideally, a fungicide application should be made before tar spot is firmly established. Once identified, tar spot can be difficult to stop. Applying fungicide between VT and R4 can help keep tar spot at bay.

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For fields with a history of tar spot, a second fungicide application later in the season can offer additional protection. Duration of leaf surface wetness appears to be a key factor in the development and spread of the disease. Scouting fields after rain events can help growers spot tar spot sooner.

“Tar spot will persist with the wet, humid weather,” Fry said. “Growers should continue walking their fields and looking for tar spot.”

Source: Corteva Agrisciencewho is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset. 

TAGS: FUNGICIDE CORN, SCOUTING, MANAGEMENT, DISEASE, CROP DISEASE

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Grahame Jackson

PestNet

 Sydney NSW, Australia

 For your information

 5 days ago

 Weird and wonderful world of fungi shaped by evolutionary bursts, study finds

Science Daily Source: University of Bristol

Summary:Scientists have discovered that the vast anatomical variety of fungi stems from evolutionary increases in multicellular complexity.Scientists at the University of Bristol have discovered that the vast anatomical variety of fungi stems from evolutionary increases in multicellular complexity.

Most people recognise that fungi come in an assortment of shapes and sizes. However, these differences, often referred to as the disparity of a group, had never been analysed collectively.

Researcher Thomas Smith, who conducted the study while at Bristol’s School of Earth Sciences, explained: “Prior to our analyses, we didn’t know how this variety was distributed across the different types of fungi. Which groups are the most varied when considering all parts of the fungal body plan? Which are the least? How has this variety accumulated and diminished through time? What has shaped these patterns in disparity? These are the questions we sought to answer.”

What they found was that fungal disparity has evolved episodically through time, and that the evolution of multicellularity in different fungi appears to open the door for greater morphological variety. They saw increases in disparity associated with both the emergence of the first multicellular fungi, and then the evolution of complex fruiting bodies such as mushrooms and saddles in dikaryotic species. These fungi are defined by the inclusion of a dikaryon, a cell with two separate nuclei, in their life cycles.

The main implication is that these results align with those of analyses of animal disparity. Both kingdoms present clumpy distributions of anatomical variety which have evolved intermittently through time.

Read on: https://www.sciencedaily.com/releases/2022/08/220815112817.htm

 Fungal_evolution

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Dear All,

The Fungal Genetics Stock Center is recruiting a new curator.  The position is available immediately.  The search will continue until a suitable candidate is identified.  Please share this information with any one you think would be a good candidate for the position. It also may be posted on appropriate job boards.

The complete job description can be found at:

https://urldefense.com/v3/__https://careers.k-state.edu/cw/en-us/job/513568/fungal-genetics-stock-center-curator__;!!PvXuogZ4sRB2p-tU!Hl6kAgEGyuYjOoGB3Epp8inI7k84Ug1q0Cwt6vwlEFHoACmdBOOP-PDKVozYquNgTGHO6uWOHyC-$ 

Applications should be submitted through the links given in the job description, and not by sending an e-mail to FGSC staff.

Thanks!

John L.

John F. Leslie, Director

Fungal Genetics Stock Center

University Distinguished Professor

Department of Plant Pathology

Kansas State University

Manhattan, Kansas, USA

########################################################################

Access the FUSARIUMLABWORKSHOP Home Page and Archives:

https://urldefense.com/v3/__http://listserv.ksu.edu/cgi-bin/wa?A0=FUSARIUMLABWORKSHOP__;!!PvXuogZ4sRB2p-tU!Hl6kAgEGyuYjOoGB3Epp8inI7k84Ug1q0Cwt6vwlEFHoACmdBOOP-PDKVozYquNgTGHO6pjeT73R$

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Global spread of powdery mildew through migration and trade

Date:August 3, 2022 Source: University of Zurich Summary: The worldwide distribution of one of the most important cereal pathogens is the result of human activity. Researchers have traced the history and spread of wheat powdery mildew along wheat trade routes and found that mixing of genetic ancestries of related powdery mildew species played a central role in the evolution and adaptation of the pathogen.Share:

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The worldwide distribution of one of the most important cereal pathogens is the result of human activity. Researchers at the University of Zurich have traced the history and spread of wheat powdery mildew along wheat trade routes and found that mixing of genetic ancestries of related powdery mildew species played a central role in the evolution and adaptation of the pathogen.

Wheat is one of the world’s most important staple foods — its significance for global food security was recently thrown into focus by the loss of grain exports from Ukraine due to the war. A more common threat to crops are fungal diseases, which can result in economic losses and famine. One of the most destructive pathogens is powdery mildew, a fungus which drastically reduces crop yields.

Agricultural arms race

To prevent infestation, huge sums are currently invested in the breeding of mildew-resistant grain varieties. In order to infect the crop plant, the pathogen must be an optimal match for its host — with resistant varieties, the fungus cannot attack. But powdery mildew constantly and rapidly adapts to new hosts. To be able to keep the disease under control in the long term, it is vital that scientists gain a better understanding of the pathogen. This is where historical data is crucial: powdery mildew is as old as wheat itself, but until now, it was not known how it had been able to spread worldwide on different grains.

A modern globetrotter

A research team led by Thomas Wicker and Beat Keller of the University Research Priority Program (URPP) Evolution in Action at the University of Zurich has now managed to uncover the secret of the wheat mildew’s success. To do so, they compared the genetic composition of 172 powdery mildew strains from 13 countries on five continents. “With our analyses we were able to prove that the mildew first appeared around 10,000 years ago in the Middle East, which is also the birthplace of agriculture and modern wheat,” explains Alexandros Georgios Sotiropoulos, PhD candidate at the Department of Plant and Microbial Biology. “In the Stone and Bronze Ages, agriculture spread to Europe and Asia. The pathogen was also spread to these new regions through human migration and trade. Around 300 years ago, European settlers introduced powdery mildew along with wheat to North and South America.”

Adaptation through rapid evolution

The data confirmed what had previously been suspected: as wheat was introduced to more and more corners of the Earth, powdery mildew was brought with it and underwent hybridization along the way, i.e. it genetically mixed with local powdery mildew species and formed hybrids that are better adapted to local agricultural environments. “This appears to be the cause of the rapid evolution of powdery mildew’s pathogenicity,” explains Kentaro Shimizu, co-director of the URPP. “A particularly clear example of this is seen in the many American wheat varieties brought to Japan over the past 120 years for cross-breeding with traditional East Asian wheat. The powdery mildew from the USA, which was also imported, hybridized with the resident Japanese mildew strains, and the resulting hybrids successfully attacked newly bred wheat varieties.”

To study the spread of powdery mildew, researchers used theoretical analyses originally created to study the evolutionary history of humankind. “Our study shows once again that collaboration between academic disciplines and the use of unconventional methods to research complex topics offers great potential and has implications for modern crop breeding,” says Kentaro Shimizu.


Story Source:

Materials provided by University of ZurichNote: Content may be edited for style and length.


Journal Reference:

  1. Alexandros G. Sotiropoulos, Epifanía Arango-Isaza, Tomohiro Ban, Chiara Barbieri, Salim Bourras, Christina Cowger, Paweł C. Czembor, Roi Ben-David, Amos Dinoor, Simon R. Ellwood, Johannes Graf, Koichi Hatta, Marcelo Helguera, Javier Sánchez-Martín, Bruce A. McDonald, Alexey I. Morgounov, Marion C. Müller, Vladimir Shamanin, Kentaro K. Shimizu, Taiki Yoshihira, Helen Zbinden, Beat Keller, Thomas Wicker. Global genomic analyses of wheat powdery mildew reveal association of pathogen spread with historical human migration and tradeNature Communications, 2022; 13 (1) DOI: 10.1038/s41467-022-31975-0

Cite This Page:

University of Zurich. “Global spread of powdery mildew through migration and trade.” ScienceDaily. ScienceDaily, 3 August 2022. <www.sciencedaily.com/releases/2022/08/220803112605.htm>.

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NEWS RELEASE 10-AUG-2022

How a harmful fungus renders its host plant defenseless

Study shows the surgical precision employed by the pathogen in this processPeer-Reviewed Publication

UNIVERSITY OF BONN

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Maize plant
IMAGE: MAIZE PLANT INFECTED WITH THE FUNGUS USTILAGO MAYDIS. view more CREDIT: © MAMOONA KHAN

Ustilago maydis attacks and reproduces in the aerial parts of the corn plant. Huge tumor-like tissue growth often form at the site of infection. These galls can reach the size of a child’s head. The growths are triggered by molecules released by the fungus, called effectors. They manipulate the plant’s metabolism and suppress its immune system. They also promote cell growth and division in corn. To do this, they interfere with a plant signaling pathway regulated by the plant hormone auxin.

“The fungus uses this auxin signaling pathway for its own purposes,” explains Prof. Dr. Armin Djamei, who heads the Plant Pathology Department at the INRES Institute of the University of Bonn. “This is because the huge growth of the tissue devours energy and resources that are then lacking for defense against Ustilago maydis. In addition, the fungus finds an ideal supply of nutrients in the growths and can multiply well there.” The formation of the characteristic galls is thus definitely in the interest of the pathogen.

“We therefore wanted to find out how the fungus promotes these proliferation processes,” says Djamei. “To do this, we searched for genetic material in the fungus that enables it to control the auxin signaling pathway of its host plant and thus its cell growth.” The complex search began seven years ago at the Gregor Mendel Institute in Vienna. Later, the crop researcher continued the work at the Leibniz Institute in Gatersleben and later at the University of Bonn.

Pathogen reprograms its host

With success: Together with his collaborators, he was able to identify five genes that the fungus uses to manipulate the host plant’s auxin signaling pathway. These five genes, called Tip1 to Tip5, form what is known as a cluster: If one imagines the entire genome of Ustilago maydis as a thick encyclopedia, these five lie, as it were, on successive pages.

Genes are construction manuals – the fungus needs them to produce respective proteins. “The proteins encoded by the five Tip genes can bind to a protein in the corn plant known to experts as Topless,” explains Dr. Janos Bindics. A former employee of the Gregor Mendel Institute, he and his colleague Dr. Mamoona Khan performed many of the study’s key experiments.

Topless is a central switch that suppresses very different signaling pathways in the plant. The fungal effectors produced by the five Tip genes override this repression – and do so very specifically for signaling pathways that benefit the fungus, such as the auxin-driven growth signaling pathway. In contrast, other signaling pathways controlled by Topless are not affected. “Figuratively speaking, the fungus acts with surgical precision,” stresses Djamei. “It accomplishes exactly what it needs to accomplish to best infect the corn plant.”

Insights for basic research

There are a number of pathogens that interfere with the auxin signaling pathway of the hosts they infect. Exactly how is often not fully understood. It may be that Topless plays an important role in this process in other crops as well. After all, the protein originated several hundreds of millions of years ago and its central role has hardly changed since then. It therefore exists not only in corn, but in a similar form in all other land plants. For example, the researchers were able to show that the Tip effectors of Ustilago maydis also interfere with the auxin signaling pathway of other plant species.

The findings could therefore help to better understand the infection processes in important plant diseases. The results are particularly interesting for basic research: “Through them, it will be possible for the first time to influence specific effects of the auxin signaling pathway in a very targeted manner and thus to elucidate the effect of these important plant hormones even more precisely,” hopes Armin Djamei, who is a member of the Transdisciplinary Research Area “Sustainable Futures” and the PhenoRob Cluster of Excellence at the University of Bonn.


JOURNAL

New Phytologist

DOI

10.1111/nph.18315 

ARTICLE TITLE

Many ways to TOPLESS – manipulation of plant auxin signalling by a cluster of fungal effectors

ARTICLE PUBLICATION DATE

10-Aug-2022

Disclaimer: AAAS and EurekAlert! are n

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NSW, Qld conditions create early stripe rust epidemic

Grain Central, August 5, 2022

There has been an increase in stripe rust infections across the north, which hasn’t surprised experts due to conducive conditions. Photo: GRDC

EXPERTS are not surprised by increasing stripe rust reports in the northern grain growing region in recent weeks, with ongoing rain and the survival of a significant green bridge over summer generating conducive conditions for the disease to thrive.

New South Wales Department of Primary Industries (NSWDPI) senior plant pathologist, Steven Simpfendorfer provided an update on cereal diseases at the Grains Research and Development Corporation’s (GRDC) Grains Research Updates last week.

Dr Simpfendorfer said across both NSW and Queensland, growers have been noticing high stripe rust occurrences in emerging crops, even reporting cases of low levels in resistant-moderately resistant (RMR) varieties like Lancer.

“We’re seeing an early epidemic this season – growers wouldn’t usually be reporting infections this early on but the significant green bridge they experienced over summer has supported earlier inoculum development,” Dr Simpfendorfer said.

“This has meant there’s significantly more seedling infections this year, including in RMR varieties, but growers who selected more resistant varieties to help manage the disease shouldn’t be too alarmed.

“Growers should be proactive and consider applying an early fungicide to manage seedling infections in later sown wheat crops as all varieties are susceptible at this stage, but once resistant varieties establish more and their adult plant resistance genetics kick in, they’ll start to look after themselves.”

Dr Simpfendorfer said growers should be out in their paddocks assessing crops closely and making informed fungicide decisions to help manage the disease while crops are most vulnerable at early growth stages.

Globally, it is estimated that over five million tonnes of wheat are lost each year to stripe rust alone.

Stripe rust trials

This season, Grain Orana Alliance (GOA) are conducting trials to determine if they can serve as an early warning system for growers to help them indicate dominant stripe rust pathotypes in different cropping areas.

It is estimated that over 5Mt of wheat are lost each year globally to stripe rust Photo: Grain Orana Alliance

GOA chief executive officer, Maurie Street said rusts are highly mobile wind-borne pathogens and move readily across the landscape.

He said, because stripe rust has several pathotypes which can impact varieties differently, growers could be caught off guard by disease infection; for example, a wheat variety resistant to pathotype 198 could be highly susceptible to pathotype 239.

Mr Street said the GOA trials will assess a range of pure seed lines with known reactions to different pathotypes of stripe rust.

“The trials will be monitored regularly and if stripe rust occurs, we’ll be able to make an informed opinion on what pathotype is likely present, but we will also send samples away to the University of Sydney to confirm the pathotype,” Mr Street said.

“This information will help growers understand which other varieties may be at immediate risk of infection in an area, giving them a head start to implement a management strategy.”

Mr Street said these trials were developed in response to feedback from growers who were concerned about the turnaround between sending crop samples away to finding out what pathotypes were impacting their crops.

“We thought about how we could address the problem and generate an early warning system to help growers respond to the threat of stripe rust in conducive conditions.”

The trial sites are located in Coolah, Tottenham, Wongarbon, Gilgandra, and Coonamble, all in central NSW.

GRDC grower relations manager – north, Vicki Green said stripe rust is a huge concern for growers this season, so extending updated research and resources to help them mitigate risk has been a high priority for the organisation.

“We invest heavily in disease management at GRDC and this season, we’ve tried to make updated information as accessible as possible to growers,” Ms Green said.

“It’s great to see our industry partners respond to grower feedback and generate avenues to help them manage disease risk during the growing season and make more informed management decisions when it comes to varietal selection.”

Source: GRDC

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Web-based tool helps blueberry growers control disease

Anthracnose fruit rot plagues blueberries, especially in Florida. In fact, it’s among the fruit’s most damaging diseases. To manage the disease, farmers normally spray the crop with fungicides, but on a calendar basis, in other words, every two or three weeks.

So, a few years ago, University of Florida scientists developed the Blueberry Advisory System, a tool to help blueberry growers fight fruit rot through a system of alerts. Now, researchers have proof the system works to help minimize fruit rot and improve crop yields.

When flowers and fruit are developing, many farmers use a calendar-based method to spray their plants to protect against the rot. With the Blueberry Advisory System, they spray when the tool sends them alerts. Notifications are received via text or email.

Growers can also use the risk assessments to choose whether to use a less-expensive fungicide when they encounter moderate disease risk or a more effective but also more expensive product during high-risk periods.

“Several Florida commercial blueberry growers have reported using the Blueberry Advisory System to help with the timing of fungicides to control anthracnose fruit rot, either by using the web-based tool alone or in combination with farmers’ own spray programs,” said Doug Phillips, UF/IFAS statewide blueberry Extension coordinator.

Clyde Fraisse, a UF/IFAS professor of agricultural and biological engineering, designed the Agroclimate system that hosts this and other disease tools. Natalia Peres, a plant pathology professor at the UF/IFAS Gulf Coast Research and Education Center, adapted and evaluated the disease models used in the system.

Peres outlines the success of the method in a new UF/IFAS Extension document.

The system can be especially useful in helping newer blueberry growers identify the disease and its dynamics,” Peres said. “It may also reduce the number of fungicide applications, especially when adopted by growers who are risk averse.”

She and her research colleagues assessed the system at nine blueberry farms spread out over Dade City (Pasco County), Fort Lonesome (Hillsborough County), and Labelle (Hendry County).

The results were good. The system notified growers to spray fungicide when fruit rot was more likely to develop, and in most cases, they didn’t need to apply the sprays as often.

Any method that helps fight disease is vital to the efforts of Florida farmers who grow blueberries. The season (from bloom through harvest) runs between December and May and includes about 5,500 acres, with an annual value of $62 million.

Blueberries are most susceptible to fruit rot in warm, wet weather, with temperatures between 59 and 81 degrees. Combine those conditions with 12-hour periods of leaf wetness, and you get ideal conditions for fruit rot to develop.

Data for the fruit rot models used by the system come from the Florida Automated Weather Network, which has weather stations throughout the state.

Rainfall or overhead irrigation can compound the problem by spreading the pathogen to healthy fruit and plants, creating additional opportunities for infection. The pathogen can also be spread by fruits touching each other and from harvesting machinery and sorting equipment.

For more information:
UF/IFAS
www.ifas.ufl.edu      

Publication date: Wed 17 Aug 2022

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TEST CONFIRMS PALM ‘BUTT ROT’ BEFORE IT’S TOO LATE

AUGUST 10TH, 2022POSTED BY LOURDES MEDEROS-U. FLORIDA

“The conk (above) is the only distinguishing symptom of the disease and indicates a palm tree is not recoverable,” says Braham Dhillon. (Credit: Lourdes Mederos/U. Florida)

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A DNA-based diagnostic method confirms a wood-decaying fungus in palms months before the symptoms of Ganoderma butt rot appear.

More than 65 species of palm trees in the United States are vulnerable to a wood-decaying fungus that can damage or destroy palms.

A fungus, Ganoderma zonatum, causes the lethal disease known as Ganoderma butt rot of palms. Its mysterious nature has stunted research for decades, making early detection of the silent killer impossible until now.

As reported in the journal Plant Disease, previously compiled sequence data from genetically validated North American Ganoderma species were used to develop the tool. The result is a diagnostic protocol that can detect the genetic make-up of the lethal Ganoderma zonatum pathogen.

“We were able to find the unique genetic markers exclusive to Ganoderma zonatum,” says Braham Dhillon, a molecular plant pathologist at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Fort Lauderdale Research and Education Center.

“This has great implications for developing management methods for the disease from this point forward. It saves time and money and opens the doors for additional research on understanding how this pathogen survives and spreads in the landscape.”

A tree specialist can collect samples as wood shavings from the trunk and submit them to a lab for diagnosis with the new procedure. Results are available in a week.

The detection method can be readily adopted into protocols of plant diagnostic facilities since the technology and equipment are routinely available without the need for additional instrumentation or chemicals.

“Early detection of the fungus, or any disease, is a crucial step towards building and implementing better disease management strategies and mitigating potential risks from palm deaths and destruction of property due to palm tree decay,” says Dhillon.

Palm trees of all varieties grace the lands of homeowners, public parks, business complexes, and roadways. The fungus, common in homeowner and public spaces, is a slow-growing pathogen, occupies the trunk, and degrades the vascular water-conducting tissue. This produces initial symptoms of wilting and dying palm fronds in the lower part of the canopy. These symptoms are also associated with other diseases like Fusarium wilt and lethal bronzing, which makes it difficult to properly diagnose.

In the later stages of the disease, a fruiting body called a conk, or basiodiomata, appears at the lower surface of the trunk and confirms the presence of Ganoderma butt rot.

“The conk is the only distinguishing symptom of the disease and indicates a palm tree is not recoverable,” says Dhillon. “The conk produces millions of spores that can travel by wind contributing to disease spread.”

As the fungus moves up the trunk, it compromises the structural integrity of the palm, says Dhillon. “In later stages of the disease, the decayed palm trunk is susceptible to breaking and becomes a hazard to properties, pedestrians, and vehicular traffic. Depending on the girth of the trunk, the decay process can take up several months to a year.”

Until now, the appearance of the conk, or an invasive dissection of the infected trunk and culturing of the fungus, are the only ways to confirm the diagnosis of the lethal disease, explains Dhillon.

For the study, scientists sequenced a variety of samples, including 24 cultures from 15 Ganoderma species collected from a previous study and archived at the Center for Forest Mycology Research Culture Collection and Herbarium, US Department of Agriculture Forest Service.

They also collected healthy and naturally infected sawdust palm samples from eight palm species. Infected palms in the study were categorized for one of two symptoms: wilted palm fronds or presence of a conk. Other samples included conks, infected tissues, soil, and DNA from palm-infected lethal yellowing and lethal bronzing specimens. Researchers validated the method on DNA isolated from 60 samples.

Source: University of Florida

Original Study DOI: 10.1094/PDIS-12-21-2837-RE

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Breeder develops disease-resistant snack cucumbers varieties

“Developing varieties with resistances takes time but it’s an important role we play as plant breeders”

Rijk Zwaan is taking innovation to new heights in snack cucumbers by focusing on high wire varieties with the combination of Powdery Mildew (PM) and Cucumber Green Mottled Mosaic Virus (CGMMV) resistance. This is the latest development in the company’s ever-growing range of flavorsome snack cucumbers in various sizes and colors, all with the best possible resistances to help growers harvest a healthy crop.

Snack varieties with resistances to CGMMV and Powdery Mildew (PM)
Since introducing Quarto RZ – one of the first varieties of snack cucumber – in 2005, Rijk Zwaan has worked with growers and listened to consumers to breed new varieties that are not only agronomically sound and productive, but also delicious and visually appealing. “Developing varieties with resistances takes time but it’s an important role we play as plant breeders,” says Marcel van Koppen, a Dutch-based crop specialist at Rijk Zwaan. “Growers face pressure from a number of diseases such as mildew as well as viruses that can have serious consequences for crop viability. In 2019, we enhanced the snack cucumber range with the introduction of Quayal RZ as a PM-resistant version of Qwerty RZ. We’ve now taken our range to the next level once again by asking our breeders to develop snack cucumber varieties with a combination of PM and CGMMV resistances. This will be a significant improvement for growers and other value chain partners.”

Innovating the snack cucumber category for consumers
It is important to keep the segment fresh and exciting, since more than 35% of consumers in some markets eat snack cucumbers. One of Rijk Zwaan’s new varieties is Quirk RZ, a unique bi-coloured ‘baby apple’ snack cucumber with a sweet taste and good shelf life. Additionally the company has made further improvements in the smaller cucumber segment, resulting in the development of one-bites as well as a white-skinned variety which looks very striking in snack cucumber medleys. 

The future is sky
Rijk Zwaan continuously conducts research into new cucumber varieties, important resistances and technical characteristics. From generation to generation, the company maintains an ongoing dialogue with growers to anticipate new challenges in changing cultivation conditions, such as high wire. That’s why most of the company’s current varieties are suitable for both umbrella and high wire systems. “The future is the sky,” they say.

For more information:
Rijk Zwaan
info@rijkzwaan.com
www.rijkzwaan.com      

Publication date: Wed 10 Aug 2022

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Banana freckle disease spreads to 12 new locations across Northern Territory

The Northern Territory government has confirmed multiple outbreaks of the fungal disease known as banana freckle. After initially being found on a single property near Rum Jungle in May, the government today identified 12 new sites of infection at Fly Creek, Batchelor, Marrakai and the Tiwi Islands.

The disease was detected last month on the government’s own Coastal Plains Research Farm and has also been confirmed on one commercial farm. The total number of infected properties has grown to 29.

NT chief plant health officer Anne Walters said government and industry were ready to announce an eradication plan for the disease, but that had now been put on hold following widespread detections.

“I don’t think anything has gone wrong … it is obviously widespread but what seems to be the case is that it’s still quite localised in those areas we’ve found it,” she said. “The pattern is not clear on how this disease is spreading, so obviously tracing will be a critical component in the next stage of the program.”

Source: abc.net.au

Publication date: Tue 9 Aug 2022

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