Archive for the ‘Plant Pathogens’ Category

Kenyan scientist warns for impact ToBRFV on African growers

Tomato farmers in Africa have been urged to be on the lookout for the ToBRFV virus that has been causing havoc in most tomato-growing countries. Speaking during African Seed Trade Association (AFSTA) Congress in September this year, Dr. Isaac Macharia, General Manager, Phytosanitary Services at the Kenya Plant Health Inspectorate Service (KEPHIS), said countries in Africa are encouraged to report the occurrence of the disease to ensure other countries prepare.

“This virus is more severe on young tomato plants and can result in 30-70% yield loss. The unique thing about this virus is that it doesn’t infect the embryo of the seed but instead contaminates the seed coat,” he added. “Its rapid spread demonstrates that ToBRFV has become a worldwide threat to tomato production. The continent needs to prepare for the negative impact of the disease in tomato production,” he said.

“There is a need to ensure we prevent the introduction of this virus in most of our countries. We can achieve that if we embrace pre-shipment testing of all imported tomato, capsicum, and eggplant seeds, regardless of their origin, using an appropriate method such as real-time Polymerase Chain Reaction,” he said. He added that there was a need to sensitize importers of tomato/capsicum seed and commercial growers to ensure early reporting of cases.

Breeders also need to work towards the development of varieties with durable resistance genes since phylogenetic analysis shows the genomic sequence of ToBRFV differs from both ToMV and TMV.  “There is also need to invest in laboratory diagnosis for diseases, including tomato diseases. This will help countries carry out continuous tests for a proportion of seed and seedlings for ToBRFV,” he added.

Since Kenya imports most tomato, capsicum, and eggplant seeds from different countries, including those where ToBFRV has been reported, Macharia says it is now mandatory for all imported tomato seeds to be tested using real-time PCR. So far, about 192 imported seeds lots have been tested since February 2021, and no positive samples have been registered so far.

A field survey was also done in 2019 and 256 leaf samples were analyzed (245 tomatoes, 10 capsicums, 1 black nightshade) and all samples tested negative. Despite the negative results, emergency measure on ToBRFV was issued to all-out trading partners and import conditions for tomato and capsicum were amended to include pre-shipment testing and upon importation. 

“We will continue to conduct continuous surveillance to ensure this virus doesn’t get to our country. We are also going to develop contingency plans to prevent spread in case of introduction,” reveals Macharia.

Read the complete article at www.standardmedia.co.ke

Publication date: Wed 17 Nov 2021

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Bees deliver organic fungicide to crops while pollinating flowers

Sustainable farming technology company Bee Vectoring Technology (BVT) has created a natural fungicide powder that eliminates mold on growing fruits. The preventative measure is delivered by bees doing what they do best – pollinating flowers. They take it directly to the flower, rather than spreading it all over the plants and soil as a traditional spraying system does. This bee-based system has been dubbed ‘natural precision agriculture’.

The fungicide is dispensed through the openings of the hives. As bees leave the hive, they move through the powder, picking up a thick coating on their legs and wings. When they land on a flower to collect pollen, the powder naturally falls off.  

With bee populations all over the world declining in number, lessening environmental pollution is a necessity for their survival. As the bees deliver the fungicide, they are reducing the need for chemicals. Growers can rent or buy hives of bees for a season or full-time, and beekeepers monitor hive health and the needed volumes of fungicide for each crop. The fungicide is available as a single ingredient or a stackable mix of powders, depending on what crop is being protected.

“Spraying products onto crops is inherently inefficient. Only a small amount of what is sprayed on an acre of farm lands on the crop flower,” explains Ashish Malik, CEO of BVT. “On the other hand, bees only visit flowers, and so all of what they are carrying can be used to inoculate the crop with a beneficial microbe to help it fight diseases and pests.”

A number of innovations are focusing on ways to help improve the resilience of hives, with Springwise spotting several new designs. These include a hive that mimics the shape of a tree, and another made from mycelium that helps repel deadly mites. 

For more information:
Bee Vectoring Technologies International 
T: (647) 660-5119

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ToBRFV in Saudia Arabia & Iran

In Iran, symptoms resembling those of tomato brown rugose fruit virus were first observed in August 2021 in tomato plants (Solanum lycopersicum) grown in a greenhouse in Isfahan province. The plants had been grown from imported seed. The identity of the virus was confirmed by RT-PCR. All plants were removed and destroyed

In Saudi Arabia, symptoms resembling those of tomato brown rugose fruit virus (Tobamovirus, ToBRFV – EPPO A2 List) were first observed in January 2021 in tomato plants (Solanum lycopersicum) grown in several greenhouses in Riyadh region. The identity of the virus was confirmed by RT-PCR and partial nucleotide sequence. ToBRFV was identified in 25 out of 45 samples taken (Sabra et al., 2021).

Source: EPPO

Publication date: Mon 29 Nov 2021

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Global cooperation fights a potentially devastating banana pandemic

A potentially devastating banana disease (Fusarium TR4) is now spreading across the tropics, threatening the livelihoods of smallholders and large commercial farmers alike, especially growers of Cavendish, the main variety of dessert banana. There have been efforts to understand and control this devastating disease, but a real solution will require international cooperation across many disciplines. In 2020, RTB supported a virtual symposium and a masterclass to share information on how TR4 spreads, how to diagnose it and insights into future control methods.ImageTR4 kills the banana plant by attacking its vascular system. M. Dita (Alliance)

A virulent strain of a soil-dwelling fungus known as Fusarium Tropical Race 4 (TR4) is threatening the world supply of bananas, and the livelihood of millions of farmers. TR4 kills the banana plant by attacking its vascular system. Disease management is complex, as the fungus persists for decades in infected fields and there are no fully effective strategies for managing TR4. 

The pathogen spreads easily through spores, in contaminated soil and planting material. The spores even cling to farmers’ shoes and farming equipment. First identified in Taiwan in 1967, TR4 spread to other Asian countries by the early 2000s. Since 2014, the disease has expanded quickly across the greater Mekong Delta, especially in Laos and Vietnam. TR4 also emerged in 2013 in Mozambique, and was more recently identified on Mayotte, an island in the Indian Ocean. In August 2019, TR4 was reported in organic banana plants in La Guajira, Colombia, while in April 2021, TR4 was spotted in northern Peru, also on an organic banana farm. So far, the Colombians have managed to contain TR4 in the department of La Guajira, although the pathogen has spread from two farms to ten. The Cavendish variety, which dominates the market for dessert bananas, is widely grown as a monocrop, facilitating the spread of the disease. However, TR4 is also starting to gradually spread into smaller-scale, more diversified banana farming systems in various Asian countries.ImageSampling a diseased banana in northern Mozambique. Surveys like this help to map the spread of TR4. G. Blomme (Alliance)

The Alliance of Bioversity and CIAT and the International Institute of Tropical Agriculture (IITA), with the support of RTB, held a two-day virtual mini-symposium which presented a state-of-the-art overview of research on this disease. In addition, a virtual Masterclass for anyone interested in the pathogen, diagnostic tools, control strategies and the impact was organized by The Alliance and IITA in the framework of ProMusa and RTB. 

During the Masterclass, banana researchers from across the globe presented current knowledge on Fusarium spread, epidemiology and control. At the virtual symposium, novel research insights were communicated. For example, how to detect viable Fusarium inoculum from environmental samples, or insights in the survival and treatment of Fusarium in water. In addition, weevils and nematodes were reported to contribute to disease spread and infection intensity. The symposium also presented new tools to detect and map TR4.

The symposium discussed biocontrol approaches, including use of the beneficial fungus Trichoderma to control TR4. The substrate left over after harvesting cultivated mushrooms could be applied to the soil to stop the spread of the disease. Groundcover root flavonoids and phenolic acids may also help stop the fungus in the soil. Researchers in China have identified beneficial bacteria closely related to the well-known Bt. Two of these Bacillus bacteria are now being screened to find the best strains for biological control of TR4. Colombian scientists are testing ammonia-based soil disinfectants to eliminate the pathogen from locations where infected mats had been removed.ImageInternal symptoms of Fusarium wilt, TR4 affecting Cavendish bananas in Colombia. M. Dita (Alliance)

The key option to mitigate the impact of Fusarium is through the use of resistant or highly tolerant germplasm. Some promising genetic material is currently available and is being used, and many other banana types are being screened for resistance. Therefore, conventional breeding, in addition to GM and CRISPR, will most likely widen the pool of resistant germplasm in the years to come. 

“The rapid spread of TR4 threatens food security across the tropics on three continents. The banana also creates lots of jobs, including many for women and youth, from farming to packing houses to retail sales. It’s heartening that the world’s experts have been able to start working together to develop the technologies that will solve this crisis,” says James Legg, leader of FP3, which helped to sponsor the symposium.ImageFemale banana exporter in Uganda. (CIP)ImageLeaves turn yellow on a diseased plantain plant. A Fusarium Race 1 affected Bluggoe plant in northern Moza

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NOVEMBER 23, 2021

For a fungus, the right ‘accessories’ can make or break a relationship with a plant

by American Phytopathological Society

Plants interact with a diversity of organisms over the course of their lifetime, but even very similar microbes can cause opposite reactions. Two strains of the fungus Fusarium oxysporum (Fo) share a core genome, but one is a beneficial endophyte while the other is a detrimental pathogen causing wilt and death. A new study, published in the Molecular Plant-Microbe Interactions journal, tried to tease apart why these two strains cause such opposite reactions, and more generally how plants respond differently to useful and harmful microbes, by exploring the interaction of these two strains with the model plant Arabidopsis.https://171f00c1a52866b7097ffbff08524c56.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html

As explained by senior author Li-Jun Ma, “strain-specific interactions with a common host are likely dictated by the accessory chromosomes from each F. oxysporum genome.” Accessory chromosomes are extra pieces of genetic material that are considered to be more plastic in that they move and change based on the lifestyle that the fungus has, unlike the core genome. Like the gadget laboratory in a spy movie, the accessory chromosomes of Fo strains contain tools used to infiltrate the plant and shut down defenses. Using closely related strains that differ in accessory chromosomes “allows a comparative study that minimizes genetic differences between strains to address the underlying mechanism that results in distinct phenotypes (growth promotion or disease or even death),” says leading author Li Guo.

In this study, metatranscriptomic data reveals that most plant genes (about 80%) are expressed similarly in response to both fungal strains across timepoints over four days. By just twelve hours, the most obvious differences in plant response are occurring. Co-first author Houlin Yu explains that “it is important to realize that plants can rapidly react to signals of microbial presence by changing their gene expression.” For example, plant defense-related genes are induced by both the endophytic and pathogenic strains, but the endophyte is better able to suppress these genes. The other host genes that varied include plant growth-related genes that were reduced in expression when the pathogen was present, whereas nitrogen uptake and metabolism genes were increased in expression (upregulated) when the endophyte was present.

The accessory chromosomes are also where a lot of the gene expression changes were seen in the fungal strains. The endophytic strain upregulated genes involved in cell signaling and nutrient transport, while the pathogenic strain unsurprisingly upregulated those enriched for virulence or detoxification roles. Identifying the fungal genes with changes in expression on the accessory chromosomes that correspond to the ultimate outcome of plant health tell researchers what to investigate further to increase disease resistance and promote plant growth. Ma emphasizes that, “This research has a profound effect on plant and perhaps even animal immunology, suggesting that cells have a remarkable flexibility and plasticity in response to microbes of same species but genetically different.”

Explore furtherFungal transplants from close relatives help endangered plants fight off disease

More information: Li Guo et al, Metatranscriptomic Comparison of Endophytic and Pathogenic Fusarium–Arabidopsis Interactions Reveals Plant Transcriptional Plasticity, Molecular Plant-Microbe Interactions (2021). DOI: 10.1094/MPMI-03-21-0063-RJournal information:Molecular Plant-Microbe InteractionsProvided by American Phytopathological Society

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Cocoa farmers urged to intensify efforts against Frosty Pod Rot during rainy season

https://www.facebook.com/v2.6/plugins/like.php?action=like&app_id=172525162793917&channel=https%3A%2F%2Fstaticxx.facebook.com%2Fx%2Fconnect%2Fxd_arbiter%2F%3Fversion%3D46%23cb%3Df1423a19531d96%26domain%3Djamaica-gleaner.com%26is_canvas%3Dfalse%26origin%3Dhttps%253A%252F%252Fjamaica-gleaner.com%252Ff255ce1e1433228%26relation%3Dparent.parent&container_width=90&font=arial&height=25&href=https%3A%2F%2Fjamaica-gleaner.com%2Farticle%2Fnews%2F20211121%2Fcocoa-farmers-urged-intensify-efforts-against-frosty-pod-rot-during-rainy&layout=button_count&locale=en_US&sdk=joey&send=false&share=false&show_faces=false&width=90https://platform.twitter.com/widgets/tweet_button.a53eecb4584348a2ad32ec2ae21f6eae.en.html#dnt=false&id=twitter-widget-0&lang=en&original_referer=https%3A%2F%2Fjamaica-gleaner.com%2Farticle%2Fnews%2F20211121%2Fcocoa-farmers-urged-intensify-efforts-against-frosty-pod-rot-during-rainy&size=m&text=Cocoa%20farmers%20urged%20to%20intensify%20efforts%20against%20Frosty%20Pod%20Rot%20during%20rainy%20season&time=1638155927311&type=share&url=https%3A%2F%2Fjamaica-gleaner.com%2Farticle%2Fnews%2F20211121%2Fcocoa-farmers-urged-intensify-efforts-against-frosty-pod-rot-during-rainy%23.YaRGldIEUCU.twitterShare2https://s7.addthis.com/static/linkedin.html#href=https%3A%2F%2Fjamaica-gleaner.com%2Farticle%2Fnews%2F20211121%2Fcocoa-farmers-urged-intensify-efforts-against-frosty-pod-rot-during-rainy&dr=&conf=username%3Dgleaneronline%26services_exclude%3D%26services_exclude_natural%3D%26services_compact%3Dfacebook%252Ctwitter%252Cprint%252Cemail%252Cpinterest_share%252Cgmail%252Clinkedin%252Cmailto%252Ctumblr%252Cmessenger%252Cmore%26product%3Dscopl-300%26pubid%3Dgleaneronline&share=imp_url%3D0%26url%3Dhttps%253A%252F%252Fjamaica-gleaner.com%252Farticle%252Fnews%252F20211121%252Fcocoa-farmers-urged-intensify-efforts-against-frosty-pod-rot-during-rainy%26title%3DCocoa%252520farmers%252520urged%252520to%252520intensify%252520efforts%252520against%252520Frosty%252520Pod%252520Rot%252520during%252520rainy%252520season%26description%3DFarmers%2520within%2520the%2520cocoa%2520industry%2520are%2520being%2520reminded%2520by%2520the%2520Ministry%2520of%2520Agriculture%2520to%2520intensify%2520their%2520efforts%2520to%2520reduce%2520the%2520resurgence%2520of%2520the%2520Frosty%2520Pod%2520Rot%2520Disease.%2520The%2520Ministry%2520says%2520the%2520advice%2520comes%2520in%2520the%2520wake%2520of%2520a%2520forecasted%2520rainy%2520season%2520that…%26smd%3Drsi%253D%2526gen%253D0%2526rsc%253D%2526dr%253D%2526sta%253DAT-gleaneronline%25252F-%25252F-%25252F61a44695e0fa01ab%25252F1%26media%3Dundefined%26hideEmailSharingConfirmation%3Dfalse%26passthrough%3Dlinkedin%253D&li=Published:Sunday | November 21, 2021 | 11:49 AM

A frosty pod rot-affected cocoa pod hangs from a tree.

Farmers within the cocoa industry are being reminded by the Ministry of Agriculture to intensify their efforts to reduce the resurgence of the Frosty Pod Rot Disease.

The Ministry says the advice comes in the wake of a forecasted rainy season that will increase the conditions for the growth and spread of the fungus.

As such, farmers are advised to consistently continue the implementation of follow-up strategies within their fields as outlined by the Ministry’s Plant Quarantine/ Produce Inspection Branch.

This includes regular pruning of trees at least twice a year with an emphasis on maintaining a manageable height of 10-12ft and allowing at least 50-70% sunlight into the field.

Sanitation measures such as weed and pest control along with the removal of infected cherrelles and pods from trees are also heavily advised.

Additionally, cocoa farmers should cover infected pods with agricultural lime and spray their fields with copper-based fungicide using a motorised mist blower.

These measures are instrumental in lessening the disease and its spread within and between fields.

The Frosty Pod Rot Disease is highly contagious and affects the fruit of the cocoa plant.

It was discovered in Jamaica in 2016 and has since caused serious damage to the cocoa industry, reducing crop yield by up to 80 per cent per year.

Since its discovery in Jamaica, the Government allocated over $300 million to tackle the disease focusing on cultural control, chemical control, research and development, surveillance, and monitoring and evaluation.

Jamaica’s cocoa is one of eight recognized by the International Cocoa Organization with 100 per cent exclusive ‘Fine Flavour’ status among cocoa-producing countries in the world.

Follow The Gleaner on Twitter and Instagram @JamaicaGleaner and on Facebook @GleanerJamaica. Send us a message on WhatsApp at 1-876-499-0169 or email us at onlinefeedback@gleanerjm.com or editors@gleanerjm.com.

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IAPPS Region X Northeast Asia Regional Center (NEARC)

Present committee members

Dr. Izuru Yamamoto, Senior Advisor

Dr. Noriharu Umetsu, Senior Advisor

Dr. Tsutomu Arie, a representative of the Phytopathological Society of Japan, the chair of Region X

Dr. Tarô Adati, a representative of Japanese Society of Applied Entomology and Zoology

Dr. Hiromitsu Moriyama, a representative of Pesticide Science Society of Japan, the secretary general of Region X

Dr. Rie Miyaura, a representative of The Weed Science Society of Japan

The Phytopathological Society of Japan and Pesticide Science Society of Japan became official partners of IYPH2020 by FAO of UN and Ministry of Agriculture, Forestry and Fisheries (MAFF) of Japan and endeavored to educate the society on plant protection. https://www.maff.go.jp/j/syouan/syokubo/keneki/iyph/iyph_os.html

Annual activities related to IAPPS especially to IPM of plant diseases, insects and weeds, and plant regulation (from April 2020 to March 2021)

The Phytopathological Society of Japan (PSJ)

2020 Kanto District Meeting, Online; Sep 21–22, 2020

2020 Kansai District Meeting, Online; Sep 21–22, 2020

2020 Tohoku District Meeting, Online; Oct 12–14, 2020

2020 Hokkaido District Meeting, Online; Oct 15, 2020

2020 Kyushu District Meeting, Online; Nov 24–26, 2020

2021 Annual Meeting, Online; Mar 17–19, 2021

Japanese Society of Applied Entomology and Zoology (JSAEZ)

65th Annual Meeting, online, March 23-26, 2021

28th Annual Research Meeting of the Japan-ICIPE Association, online, March 25, 2021

Pesticide Science Society of Japan

37rd Study Group Meeting of Special Committee on Bioactivity of Pesticides, online, Sep 18, 2020

40th Symposium of Special Committee on Agricultural Formulation and Application, Yokohama, Kanagawa; Oct 15–16, 2020 (Cancelled due to the spread of COVID-19)

43th Annual Meeting of Special Committee on Pesticide Residue Analysis, online, Nov. 5–6, 2020

46th Annual meeting, Fuchu, Tokyo and Online, March 8–10, 2021

The Weed Science Society of Japan (WSSJ)

2020 Annual Meeting, The Weed Science Society of Kinki, Online; Dec 5, 2020

35th Symposium of Weed Science Society of Japan, Online; Dec 12, 2020

2020 Annual Meeting, Kanto Weed Science Society, Online; Dec 22, 2020

22th Annual Meeting, The Weed Science Society of Tohoku, Japan, Online; Feb 25, 2021

2020 Study Group Meeting of Weed Utilization and Management in Small Scale Farming, Online; Feb 26, 2021

Hono-Kai (means, Meeting who are appreciating agriculture)

35th Hono-Kai Symposium was cancelled due to the epidemic of COVID-19

Japan Biostimulants Association

rd Symposium, Online; Nov 2–30, 2020

Nodai Research Institute

2020-1 Biological Control Group Seminar, Setagaya; Tokyo; Jun 16, 2020 (Cancelled due to the epidemic of COVID-19)

2020-2 Biological Control Group Seminar, online, Nov 13, 2020

2021-1 Biological Control Group Seminar, online, Jun 15, 2021

2021-2 Biological Control Group Seminar, online, Nov 9, 2021

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Dear Colleagues and Friends,

I want to announce that the handbook I developed together with to other editors and 70 chapter authors on: “Integrated Nematode Management: state-of-the-art and visions for the future”

is now officially available, gratis, in open-access format on the CABI website.

The book can be download for direct viewing on your computer or smart phone or both or saved as a pdf for future use.

Please forward this link to anyone you know who might be interested in what we feel is an important hand book on applied plant pathology and nematology.

The link to the e-Book is available on the CABI website at:


The editors put together the 500 pages of science in 65 chapters with over 250+ figures in the 12 month window we set. Good collaborators.

I look forward to any comments you have and hope the vast majority are positive! Of course nothing is perfect.

All the best over the holiday season whether Thanksgiving, Christmas, New Years or other special occasion.

Sincerely yours

Richard Sikora



Richard A. Sikora, Prof. em.

Institute for Crop Science & Resource Conservation Consultant Plant Health Management University of Bonn, Germany

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BBTD Alliance continues to tackle banana bunchy top disease in Africa

Up to 16 African countries have now experienced the banana bunchy top disease (BBTD), caused by the banana bunchy top virus. The virus is also endangering the diversity of banana varieties grown by these farmers. The CGIAR Research Program on Roots, Tubers and Bananas (RTB) is combating the virus through the Alliance for Banana Bunchy Top Disease Control in Africa.

The BBTD Alliance convened international, multi-stakeholder teams fostering cutting-edge research for development (R4D) to establish practical solutions so farmers can once again produce bananas for food and income. The Alliance has collaborated with national programs, building their capacity to detect, surveil, and control BBTD.

The BBTD Alliance develops new knowledge and management technologies, facilitates training and information exchange, and supports national partners and farmer organizations. Seed entrepreneurs, extension agents, farmers, and plant health inspectors are learning to diagnose the disease in the field, identify rogue infected plants, and produce clean planting material. In 2020, RTB developed an online training course on disease recognition and eradication.

Source: iita.org

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New paddy variety on 250 acres hit by rice blast disease in Wayanad

E.M. ManojKALPETTA, NOVEMBER 12, 2021 21:45 ISTUPDATED: NOVEMBER 12, 2021 21:45 IST

Scientists of the Regional Agricultural Research Station, Ambalavayal, visiting a paddy farm affected by the rice blast disease, under the Cheekkallur Padashekhara Samiti in Wayanad district.   | Photo Credit: Special Arrangement

Expert says ‘Manuvarna’ strain was intended for cultivation in kole fields and wetland ecosystems

Rice blast, a fungal disease affecting paddy, is haunting farmers who had raised “Manuvarna”, a new rice variety released by the Kerala Agricultural University recently, on more than 250 acres in Wayanad district.

K. Kesava Marar, president of the Cheekkallur Padashekhara Samiti, cultivated the new rice variety on 70 acres of rented land after learning from some farmers in Palakkad district that it had given higher yields than the traditional rice varieties.

Mr. Marar, along with 60 other farmers of the samiti, procured the 4,600 kg of seeds from the Kerala Agricultural University at a cost of ₹42 kg.

However, they noticed a few weeks ago that the crop cultivated on more than 250 acres of land was damaged owing to the blast disease.

The blast disease is caused by the fungus Pyricularia oryzae which is non-systemic in action. The spores of the fungus could have been released from hosts like Purple nutsedge and Echinochloa crusgalli (Muthanga and Kavada respectively in local parlance) which are abundantly present in the paddy fields, bunds, and on sides of irrigation channel of the affected area. This would have resulted in an increased concentration of spores in the air. Relative humidity of more than 93% and rainfall below 5 mm per day are the major predisposing factors especially during the mid tillering stage of the crop for the incidence of the blast, RARS sources said.

The ‘Manuvarna’ variety of paddy was released for the low lands of Kerala, especially for the kole lands, wetland ecosystem, K. Ajith Kumar, Associate Director, RARS, told The Hindu.

Adoption of prophylactic measures of management would have substantially reduced the severity of blast disease incidence, Dr . Ajithkumar said. However, such measures were not taken properly in the affected area which led to severe damage due to the incidence of neck blast, he said.

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Tar spot gains attention of USDA-ARS

Tom J. Bechmancorn leaf with signs of tar spotEARLY STAGES: Agronomists say growers need to learn to identify tar spot at this stage. This specimen was growing in Bayer’s fungicide demonstration plots at the Farm Progress Show.Hi-Tech Farming: The newest corn disease in the U.S. is targeted by researchers.

Tom J Bechman | Nov 18, 2021

Tar spot was first detected in the U.S. in 2015, but it now has the undivided attention of a USDA Agricultural Research Service research team based in West Lafayette, Ind. Growers fight this corn disease with fungicides. However, Steve Goodwin, an ARS plant pathologist, says plants that have resistance to tar spot are preferable.

While participating universities conduct research on timing of fungicides and other control measures, Goodwin and his team are concentrating on four fronts:

1. Screening current material. The team is screening existing commercial varieties and germplasm lines for resistance or susceptibility to tar spot. The goal is to help growers adjust management practices as soon as possible depending upon which hybrids they grow.

2. Developing molecular markers. These tools will identify Qrtsc8, the gene that confers tar spot resistance. Investigators are also exploring why some plants that lack this gene are still resistant, since an unknown gene or genes could be involved.

3. Determining biocontrol potential. A microbiome of organisms was found on tar spot-resistant plants, but not on susceptible plants. Researchers want to know how these organisms, plant growth stage and the environment are interconnected in the progression of tar spot.

4. Understanding how tar spot works. Scientists also want to learn how the tar spot fungus uses several proteins to short-circuit defenses of susceptible plants. Identification of these proteins could lead to better detection of different strains of the fungus and its severity in the field.

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