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Almond Bloom
The four main fungal diseases in almonds, which can do the most damage to the crop, are brown rot, anthracnose, shot hole, and jacket rot. All four are different and have different sensitivities to fungicides.

Cecilia Parsons | Mar 01, 2017

Warm and wet weather as the Central Valley’s almond orchards burst into bloom makes widespread fungal diseases almost a sure bet.

“If growers get behind on their control and can’t get the fungicide sprays on, they might get hammered this year,” warns Dani Lightle, University of California Cooperative Extension (UCCE) farm advisor in the Northern California counties of Glenn, Butte, and Tehama.

Lightle says, “If pathogens get a foothold and it rains through bloom and after, there may be a lot of crop damage. You can’t catch up with these diseases.”

David Doll, UCCE farm advisor at Merced County, says fungicide applications are a preventative measure, not a control. Wet conditions during this year’s bloom created a perfect environment for fungal growth.

The pathogens are always present in an orchard, Doll explains, but they need a host and the right environmental conditions. Continued warm and wet conditions during bloom can open the doors for fungal infections.

“With no fungicide applications and current conditions, significant yield losses can be expected,” Doll said. “Depending on the variety, it could be 20-30 percent.”

On Feb. 1, the California Department of Pesticide Regulation approved the aerial application of fungicides in six North State counties due to the number of almond orchards inaccessible with ground spray rigs.

The exemption allows for fungicide applications in orchards with standing water. No pumping of water is allowed after the applications and the sprays must cease if a rain event is imminent.

The four main fungal diseases in almonds, which can do the most damage to the crop, are brown rot, anthracnose, shot hole, and jacket rot. All four are different and have different sensitivities to fungicides, according to Doll.

ANTHRACNOSE

Anthracnose symptoms include blossom blight and fruit infections often with spur and limb dieback. Infected flowers appear similar to brown rot strikes. Infected nuts show round, orange-colored sunken lesions on the hull with symptoms appearing about three weeks after petal fall. Nuts can be infected later in the season if conditions are favorable.

Diseased nuts become mummified but remain attached to the spur. Shoots or branches with infected nuts often die. UC Integrated Pest Management (IPM) guidelines report that all cultivars are susceptible.

Management calls for fungicide treatments beginning at 5-10 percent bloom and repeated every 10-14 days if wet weather persists. Specific materials and application rates can be found on the IPM web site.

BROWN ROT

Almond blossoms are most susceptible to brown rot when fully open. Stigma, anthers, and petals are all susceptible to brown rot infection. Gum may secrete from the base of infected flowers.

This fungus survives on twig cankers and on remaining diseased flower parts and spurs. Spores are airborne or water splashed, and infections spread rapidly in wet weather with temperatures in the mid-70s.

Timing for control should be determined by the bloom of the most seriously affected cultivar. If infections were widespread the previous year, multiple fungicide applications may be necessary.

SHOT HOLE

Symptoms of shot hole include spots on leaves, hulls, twigs, and flowers. Leaf lesions begin as tiny reddish specks. Spots on young leaves will fall out leaving a shot hole appearance. Older leaves retain the lesions.

Heavy infections can cause nutlets to drop, become distorted, or gum up. Infected trees will weaken, defoliate, and lose production.

There is a high risk of shot hole development in the spring if shot hole lesions with fruiting structures are found on leaves in the fall. Fruiting structures appear in the center of leaf lesions as small black spots, viewable with a hand lens.

Fungicide applications depend on weather conditions and the level of infection found in the fall.

JACKET ROT

Jacket rot, or green fruit rot, begins later in the bloom period when the fungus infects petals and anthers. The infection can spread to floral tubes or flower jackets causing them to wither and stick to developing nutlets. Entire nut clusters can rot if covered with the infected flower parts.

Jacket rot is not as prevalent as the three other fungal diseases and is more likely to appear in cooler weather conditions. Fungicide should be applied at full bloom to prevent jacket rot.

Lightle says targeting fungicide choices to the fungal disease of concern is vital. She encouraged use of the fungicide efficacy tables available at http://ipm.ucanr.edu/PMG/r3902111.html.

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Spread of damaging wheat rust continues: new races found in Europe, Africa, Central Asia

Mediterranean particularly affected by new rust races

Photo: ©FAO/ Fazil Dusunceli

Wheat experts examine a research plot near Izmir, Turkey, affected by wheat yellow rust.

3 February 2017, Rome −  Wheat rust, a family of fungal diseases that can cause crop losses of up to 100 percent in untreated susceptible wheats, is making further advances in Europe, Africa and Asia, according to two new studies produced by scientists in collaboration with FAO.

The reports, highlighted in the journal Nature following their publication by Aarhus University and the International Maize and Wheat Improvement Center (CIMMYT), show the emergence of new races of both yellow rust and stem rust in various regions of the world in 2016.

At the same time, well-known existing rust races have spread to new countries, the studies confirm, underlining the need for early detection and action to limit major damage to wheat production, particularly in the Mediterranean basin.

Wheat is a source of food and livelihoods for over 1 billion people in developing countries. Northern and Eastern Africa, the Near East, and West, Central and South Asia – which are all vulnerable to rust diseases − alone account for some 37 percent of global wheat production.

“These new, aggressive rust races have emerged at the same time that we’re working with international partners to help countries combat the existing ones, so we have to be swift and thorough in the way we approach this,” said FAO Plant Pathologist Fazil Dusunceli. “It’s more important than ever that specialists from international institutions and wheat producing countries work together to stop these diseases in their tracks −  that involves continuous surveillance, sharing data and building emergency response plans to protect their farmers and those in neighboring countries.”

Wheat rusts spread rapidly over long distances by wind. If not detected and treated on time, they can turn a healthy looking crop, only weeks away from harvest, into a tangle of yellow leaves, black stems and shriveled grains.

Fungicides can help to limit damage, but early detection and rapid action are crucial. So are integrated management strategies in the long run.

wheat_stem-rust_1Stem rust

Mediterranean most affected by new rusts

On the Italian island of Sicily, a new race of the stem rust pathogen −called TTTTF− hit several thousands of hectares of durum wheat in 2016, causing the largest stem rust outbreak that Europe has seen in decades. Experience with similar races suggests that bread wheat varieties may also be susceptible to the new race.

TTTTF is the most recently identified race of stem rust. Without proper control, researchers caution, it could soon spread over long distances along the Mediterranean basin and the Adriatic coast.

Various countries across Africa, Central Asia and Europe, meanwhile, have been battling new strains of yellow rust never before been seen in their fields.

Italy, Morocco and four Scandinavian countries have seen the emergence of an entirely new, yet-to-be-named race of yellow rust. Notably, the new race was most prevalent in Morocco and Sicily, where yellow rust until recently was considered insignificant. Preliminary analysis suggests the new race is related to a family of strains that are aggressive and better adapted to higher temperatures than most others.

Wheat farmers in Ethiopia and Uzbekistan, at the same time, have been fighting outbreaks of yellow rust AF2012, another race which reared its head in both countries in 2016 and struck a major blow to Ethiopian wheat production in particular. AF2012 was previously only found in Afghanistan, before appearing in the Horn of Africa country last year, where it affected tens of thousands of hectares of wheat.

“Preliminary assessments are worrisome, but it is still unclear what the full impact of these new races will be on different wheat varieties in the affected regions,” said Dusunceli. “That’s what research institutions across these regions will need to further investigate in the coming months.”

To offer support, FAO, in collaboration with its partners, is stepping up its efforts in training rust experts from affected countries to boost their ability to detect and manage these emerging wheat rust races.

As new races emerge, old ones continue to spread

The already established Warrior(-) race of yellow rust − which came onto scientists’ radars in Northern Europe and Turkey a few years ago −  continued its aerial march in 2016 and is now widely present in Europe and West Asia.

The Digalu (TIFTTF) race of stem rust continues to devastate wheats in Ethiopia, while the most well-known race of stem rust – the highly potent Ug99 – is now present in 13 countries. Having spread in a northward trend from East Africa to the Middle East, Ug99 has the potential to affect many wheat varieties grown worldwide as it keeps producing new variants. Most recently, it has been detected in Egypt, one of the Middle East’s most important wheat producers.

International collaboration crucial

The findings of the Aarhus study build on training sessions conducted in 2016 in collaboration between the International Center for Agricultural Research in the Dry Areas (ICARDA), Aarhus university, CIMMYT and FAO.

The training, which will be repeated this year, allows rust experts to strengthen their surveillance and management skills, coupled with surveys and collection of rust samples for tests and analysis by Aarhus University. The recently established Regional Cereal Rust Research in Izmir, Turkey, will host the training.

These efforts have been part of FAO`s four-year global wheat rust program, which facilitates regional collaborations and offers support to individual countries eager to boost their surveillance capacity.

It also helps countries act swiftly to control outbreaks before they turn into epidemics and cause major damage to food security. But further research, particularly into breeding resistant varieties, and national response plans need to be backed by adequate resources.

FAO, CIMMYT, ICARDA and Aarhus University are working together as members of the Borlaug Global Rust Initiative (BGRI).

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IBIS daily digest

Morning Agclips

WHEAT DISEASE …

Found in Europe, Africa, Central Asia; Mediterranean particularly impacted

Wheat experts examine a research plot near Izmir, Turkey, affected by wheat yellow rust. (Courtesy Photo)

 

ROME — Wheat rust, a family of fungal diseases that can cause crop losses of up to 100 percent in untreated susceptible wheats, is making further advances in Europe, Africa and Asia, according to two new studies produced by scientists in collaboration with FAO.

The reports, highlighted in the journal Nature following their publication by Aarhus University and the International Maize and Wheat Improvement Center (CIMMYT), show the emergence of new races of both yellow rust and stem rust in various regions of the world in 2016.

At the same time, well-known existing rust races have spread to new countries, the studies confirm, underlining the need for early detection and action to limit major damage to wheat production, particularly in the Mediterranean basin.

Wheat is a source of food and livelihoods for over 1 billion people in developing countries. Northern and Eastern Africa, the Near East, and West, Central and South Asia – which are all vulnerable to rust diseases − alone account for some 37 percent of global wheat production.

“These new, aggressive rust races have emerged at the same time that we’re working with international partners to help countries combat the existing ones, so we have to be swift and thorough in the way we approach this,” said FAO Plant Pathologist Fazil Dusunceli. “It’s more important than ever that specialists from international institutions and wheat producing countries work together to stop these diseases in their tracks −  that involves continuous surveillance, sharing data and building emergency response plans to protect their farmers and those in neighboring countries.”

Wheat rusts spread rapidly over long distances by wind. If not detected and treated on time, they can turn a healthy looking crop, only weeks away from harvest, into a tangle of yellow leaves, black stems and shriveled grains.

Fungicides can help to limit damage, but early detection and rapid action are crucial. So are integrated management strategies in the long run.

Mediterranean most affected by new rusts

On the Italian island of Sicily, a new race of the stem rust pathogen −called TTTTF− hit several thousands of hectares of durum wheat in 2016, causing the largest stem rust outbreak that Europe has seen in decades. Experience with similar races suggests that bread wheat varieties may also be susceptible to the new race.

TTTTF is the most recently identified race of stem rust. Without proper control, researchers caution, it could soon spread over long distances along the Mediterranean basin and the Adriatic coast.

Various countries across Africa, Central Asia and Europe, meanwhile, have been battling new strains of yellow rust never before been seen in their fields.

Italy, Morocco and four Scandinavian countries have seen the emergence of an entirely new, yet-to-be-named race of yellow rust. Notably, the new race was most prevalent in Morocco and Sicily, where yellow rust until recently was considered insignificant. Preliminary analysis suggests the new race is related to a family of strains that are aggressive and better adapted to higher temperatures than most others.

Wheat farmers in Ethiopia and Uzbekistan, at the same time, have been fighting outbreaks of yellow rust AF2012, another race which reared its head in both countries in 2016 and struck a major blow to Ethiopian wheat production in particular. AF2012 was previously only found in Afghanistan, before appearing in the Horn of Africa country last year, where it affected tens of thousands of hectares of wheat.

“Preliminary assessments are worrisome, but it is still unclear what the full impact of these new races will be on different wheat varieties in the affected regions,” said Dusunceli. “That’s what research institutions across these regions will need to further investigate in the coming months.”

To offer support, FAO, in collaboration with its partners, is stepping up its efforts in training rust experts from affected countries to boost their ability to detect and manage these emerging wheat rust races.

As new races emerge, old ones continue to spread

The already established Warrior(-) race of yellow rust − which came onto scientists’ radars in Northern Europe and Turkey a few years ago −  continued its aerial march in 2016 and is now widely present in Europe and West Asia.

The Digalu (TIFTTF) race of stem rust continues to devastate wheats in Ethiopia, while the most well-known race of stem rust – the highly potent Ug99 – is now present in 13 countries. Having spread in a northward trend from East Africa to the Middle East, Ug99 has the potential to affect many wheat varieties grown worldwide as it keeps producing new variants. Most recently, it has been detected in Egypt, one of the Middle East’s most important wheat producers.

International collaboration crucial

The findings of the Aarhus study build on training sessions conducted in 2016 in collaboration between the International Center for Agricultural Research in the Dry Areas (ICARDA), Aarhus university, CIMMYT and FAO.

The training, which will be repeated this year, allows rust experts to strengthen their surveillance and management skills, coupled with surveys and collection of rust samples for tests and analysis by Aarhus University. The recently established Regional Cereal Rust Research in Izmir, Turkey, will host the training.

These efforts have been part of FAO`s four-year global wheat rust program, which facilitates regional collaborations and offers support to individual countries eager to boost their surveillance capacity.

It also helps countries act swiftly to control outbreaks before they turn into epidemics and cause major damage to food security. But further research, particularly into breeding resistant varieties, and national response plans need to be backed by adequate resources.

FAO, CIMMYT, ICARDA and Aarhus University are working together as members of the Borlaug Global Rust Initiative (BGRI).

–FAO

– See more at: https://www.morningagclips.com/spread-of-damaging-wheat-rust-continues/#sthash.xFba0wMD.dpuf

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Weird year for Sicilian citrus fruit

“Citrus fruit production this year is quite low, especially for oranges. Producers not only had to deal with the CTV-Citrus Tristeza Virus, but also with a whole lot of other factors – mild temperatures during the past winters, lower blossoming, wider yield alternance. In addition, it rained a lot in September,” reports Corrado Vigo, agronomist and President of the Ordine dei Dottori Agronomi e dei Dottori Forestali in Catania.

For what concerns the rain/drought, Vigo explains that “I have noticed these events are cyclical, they occur every 10-11 years. What is weird is that this cycle coincides with the Sun cycle. We are expecting some more rain in December as well.”

In addition to the weather conditions, there is a series of fungi, pathogens and Phytophthora that, with the temperatures registered so far, spread. “For example, the persistent rain in September triggered Phytophthora citrophthora, which led to a loss of fruit. In addition, in October, there was a late attack of Ceratitis capitata“.

There are a lot of drops of yet unripe oranges as well as a lot of mouldy fruit on the trees. The areas of Scordia, Lentini, Palagonia and Mineo were affected by dessicating wind, which damaged both the fruit and the leaves. “We already expected a drop in volumes, but now they will be even lower.”

Varietal innovation
“There are very few innovative varieties. Producers are looking to replace the trees (especially because of the Citrus Tristeza Virus), but costs are high. The last PSR call for bids, for example, ended in 2012 and the new one hasn’t opened yet. If we consider that, last year, oranges sold at 4 cents, we can see how it might be difficult to end the year positively, let alone make investments.”

We must also keep in mind that orchard response times are slow. “We are talking about seven/eight years for a full production cycle. Another problem is the availability of plants. In Sicily, we generate around 1.5/2 million plants. To reconvert the areas affected, 24-25 million plants are needed and it would take 12-13 years.”

Competition
“Just like every year, our citrus fruit is available on the market as well as oranges from Spain and grapefruit from Israel, for example.”
“I keep thinking about the French, who only buy produce made in France before anything else. Only then do they look for something foreign. In Italy, it seems as if we welcome foreign produce.”

Contacts:
Corrado Vigo
Email: corrado@vigo.it
Web: www.vigo.it

 

Publication date: 12/8/2016

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glp_logo_2016-06

New GMO could protect wheat and barley against deadly blight

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fhb-2-033

Fusarium head blight (FHB), caused by Fusarium graminearum, is a devastating disease of wheat and barley that leads to reduced yield and mycotoxin contamination of grain, making it unfit for human consumption. FHB is a global problem, with outbreaks in the United States, Canada, Europe, Asia and South America. In the United States alone, total direct and secondary economic losses from 1993 to 2001 owing to FHB were estimated at $7.67 billion1. Fhb1 is the most consistently reported quantitative trait locus (QTL) for FHB resistance breeding. Here we report the map-based cloning of Fhb1 from a Chinese wheat cultivar Sumai 3. By mutation analysis, gene silencing and transgenic overexpression, we show that a pore-forming toxin-like (PFT) gene at Fhb1 confers FHB resistance. PFT is predicted to encode a chimeric lectin with two agglutinin domains and an ETX/MTX2 toxin domain. Our discovery identifies a new type of durable plant resistance gene conferring quantitative disease resistance to plants against Fusarium species.

The GLP aggregated and excerpted this blog/article to reflect the diversity of news, opinion, and analysis. Read full, original post: Wheat Fhb1 encodes a chimeric lectin with agglutinin domains and a pore-forming toxin-like domain conferring resistance to Fusarium head blight

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global-plant-council-logo

University of Guelph plant scientists have shown for the first time how an ancient crop teams up with a beneficial microbe to protect against a devastating fungal infection, a discovery that may benefit millions of subsistence farmers and livestock in developing countries.

Their discovery may also point the way toward a natural treatment to thwart the pathogen in other important crops grown worldwide including corn and wheat, said plant agriculture professor Manish Raizada.

He’s senior author of a paper published in Nature Microbiology. He worked with lead author and former PhD student Walaa Mousa, current graduate student Charles Shearer, Ridgetown Campus scientist Victor Limay-Rios and researchers in California.

The paper describes a novel defence mechanism allowing crop plants to work with bacteria called endophytes living in their roots to ward off Fusarium graminearum. This fungus makes a toxin that can sicken livestock and people.

The M6 microbe lives in the roots of finger millet, a cereal crop grown by subsistence farmers in Africa and South Asia. Millions of people rely on the crop, first domesticated in East Africa in about 5,000 BC.

The crop has long been known to be resistant to fungal disease. Through microscope observations, Mousa learned how the mechanism works. Sensing the pathogen near the plant roots, the microbe enters the soil and multiplies to millions of cells that form a protective barrier on the root surface.

Even more striking, he said, the plant’s root hairs grow to many times their normal length. Like layers in lasagna, the root hairs and the bacterial cells form a dense mat that traps the fungus.

Mousas found that natural products of these endophytic bacteria then kill the fungus. Raizada said, “This appears to be a new defence mechanism for plants.” He likens the mechanism to the human immune system, with immobile plant cells “recruiting” mobile microbes to seek out and destroy pathogens.

The researchers believe this mechanism evolved in a kind of evolutionary arms race in the African ancestors of finger millet and Fusarium. The fungus can make an antibiotic against M6 for which the bacterium has developed resistance in turn, Raizada said.

“We think subsistence farmers in East Africa over generations may have selected for this special microbe through breeding.”

He said the findings may help agricultural companies develop seed treatments using M6 to protect more susceptible and widely grown crops such as corn and wheat against the fungus.

Farmers spend tens of millions of dollars fighting crop diseases such as Fusarium.

U of G has licensed the lab’s results to an agricultural startup company for potential use in those crops. The microbe is now being tested in Canadian corn and wheat. The team found that M6 also protects against other fungi.

He said the study shows the importance of indigenous farming knowledge and practices. “These crops should be explored and valued.”

Read the paper: Root-hair endophyte stacking in finger millet creates a physicochemical barrier to trap the fungal pathogen Fusarium graminearum.

Article source: University of Guelph

Image credit: University of Guelph

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ucr-today

Researchers develop strategy that could lead to environmentally friendly fungicide to fight pathogens that cause billions of dollars in crop loss

gray mold on fruit, vegetables and flowersThe images third from the bottom and at the bottom show fruit, vegetables and flowers treated with pathogen gene-targeting RNA molecules. The other images represent various control methods.

 

RIVERSIDE, Calif. (www.ucr.edu) — Have you ever bought strawberries or other fruits and vegetables, forgot to put them in the refrigerator and later noticed they had gray mold on some of them?

That’s Botrytis cinerea, a fungal pathogen that can infect more than 1,000 plant species, including almost every fruit and vegetable and many flowers. Wine grapes are also a notable host – in grapes the condition is known as bunch rot. It causes billions of dollars in crop loss annually.

A team of researchers, led by Hailing Jin, a University of California, Riverside professor of plant pathology and microbiology, have developed a new strategy that could provide an easy-to-use and environmentally friendly fungicide to fight B. cinerea and other fungal pathogens that harm crops.

The findings were just published in the journal Nature Plants.

These findings build on a paper by Jin’s group published in 2013 in the journal Science. In that paper, they outlined how they discovered the mechanism by which B. cinerea infects plants.

Many pathogens secrete protein effectors molecules to manipulate and – eventually – compromise host immunity. The researchers, led by Jin, found three years ago for the first time that B. cinerea can deliver small RNA effector molecules to the host cells to induce cross-kingdom RNA interference (RNAi) to suppress host immunity.

Building on that work, in the just-published study in Nature Plants, they discovered that such cross-kingdom RNAi is bidirectional, meaning small RNAs can flow from the pathogen to the host and from the host to the pathogen.

Furthermore, they found that B. cinerea is capable of taking up RNA molecules from the environment, which makes it possible to use such external RNAs in fungicidal sprays to manage diseases.

The researchers tested that idea and found that applying those pathogen gene-targeting RNA molecules to the surface of fruits and vegetables and flowers – they used tomato, strawberry, grape, lettuce, onion, and rose – can control gray mold diseases.

The findings outlined in the Science and Nature Plants papers have significant implications for farmers looking to control fungal pathogens. Currently, fungicides and chemical spraying are still the most common disease control strategy. But, these treatments pose serious threats to human health and environments. RNA, which is present in all living organisms, doesn’t present problems for human health and it naturally degrades in soil.

While the research focused on the fungal pathogens B. cinerea and Verticillium dahliae, another fungal pathogen that causes wild disease on dozens of trees, shrubs, vegetables, and fields crops, the researchers believe this RNAi-based technique could be used to control multiple pathogens at the same time.

While the research focused on the fungal pathogen B. cinerea, the researchers believe the technique could be used to control other fungal pathogens, such as Verticllium dahliae, which causes wild disease on dozens of trees, shrubs, vegetables, and fields crops.

It also has the potential to decrease the use of GMOs by providing an effective, environmentally friendly way to control plant diseases.

The Nature Plants paper is called “Bidirectional cross-kingdom RNAi and fungal uptake of external RNAs confer plant protection.” In addition to Jin, the authors are Ming Wang and Arne Weiberg, both of UC Riverside; Arne Weiberg, who recently got a faculty position at the University of Munich; Feng-Mao Lin and Hsien-Da Huang, both of National Chiao Tung University in China; and Bart P. H. J. Thomma of Wageningen University in the Netherlands.

This research was supported by grants Jin received from the National Science Foundation and National Institutes of Health.

The invention has a patent pending status.

 

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