Popular Fungicides Failing, May Cause Hard Choices for Apple Growers

[Seamaiden]

ScienceDaily (July 12, 2011) — Orchard growers have started finding that some of the most commonly used fungicides are no longer effective at controlling apple scab, according to a Purdue University study.

Janna Beckerman, an associate professor of botany and plant pathology, said that extensive, long-term use of four popular fungicides has led to resistances in apples in Indiana and Michigan, the focus of her study.

"The fungicides that are regularly used to control scab have started to fail," said Beckerman, whose findings were published in the early online version of the journal Plant Disease. "But the most disturbing thing we found is that many of the samples we tested were resistant to all four fungicides. It's kind of like multidrug resistance in antibiotics. This is full-blown resistance."

Apple scab, caused by the fungus Venturia inaequalis, is highly destructive to apples, causing brown lesions on leaves and fruit. A single lesion can reduce an apple's value by 85 percent. Over time, the scabby lesion will crack and allow insects, other fungi and bacteria inside, causing a loss of the crop.

"It can cause orchard failures," Beckerman said. "An orchard grower that has this could lose blocks of an orchard, or depending on the amount of diversity in the orchard, they could lose the entire crop."

It's thought that when organisms adapt to form resistance, that change will weaken the organism in some other way. Beckerman said the study, done with Purdue graduate student Kim Chapman and Michigan State University professor George Sundin, showed apple scab, on the contrary, is becoming resistant to fungicides with no apparent fitness penalty to itself.

"Having these multiple resistances to fungicides doesn't debilitate them in any way," Beckerman said.

Apple scab samples were treated with dodine, kresoxim-methyl, myclobutanil or thiophanate-methyl. About 12 percent of the apple scab samples tested was resistant to all four fungicides.

The only options apple growers have, Beckerman said, is to use older fungicides that are tightly regulated, require more frequent application and are more expensive.
"It's going to change how growers manage their orchards," Beckerman said. "The more susceptible apple cultivars, like McIntosh, will become more chemically intensive to manage. Growers have few options as it is, and this will limit their options even further."

Beckerman said she and her collaborators would work to develop faster tests to detect fungicide resistance in apple scab to help growers change management plans in a timely manner. The U.S. Department of Agriculture, Purdue University and the Michigan Agricultural Experiment Station funded the research.

 

[Chronic Monster]

Good read Sea!

 

[BudGood]

So were these orchards using a rotation of fungicides? Did the fungus get resistant from not using IPM principles in managing it correctly?? The implications of this is interesting to say the least! This should make those who misuse pesticides think as well! :fighting0085:

Very good read, thanks Seamaiden! :smiley_joint:

 

[Seamaiden]

More related from SD. :)



New Switch in Resistance to Plant Diseases Discovered

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The protein MAGAP1, molecular antagonist of the susceptibility factor RACB, in the cytoskeleton of barley (green-blue). Shown in red is the nucleus near the place where a mildew fungus tries to penetrate. (Credit: Caroline Hoefle / TUM)

ScienceDaily (July 12, 2011) — Powdery mildew is a tricky pathogen: The fungus can manipulate barley in a way that it is not only granted entry into the plant, but also gets the plant's cells to supply it with nutrients. A team of researchers at Technische Universitaet Muenchen in Germany has just identified, on a molecular level, how the fungus manages this feat -- and how barley can fight back.

The results have now been published in the Plant Cell.

Plants, too, have an immune system that protects them against diseases. The early detection of pathogens and the subsequent immune response, in particular at the cell wall, work as a protective shield. However, the pathogens that cause plant diseases have their weapons, too. Some are able to suppress the natural cell wall reaction in plants. "One particularly ingenious attacker, powdery mildew, can even reprogram cells in such a way that they adapt their architecture and metabolism to accommodate the fungus. The plant thus actively fosters the in-growth of the harmful mildew and even supplies it with nutrients," explains Prof. Ralph Hückelhoven from the TUM Chair of Phytopathology. How the mildew manages this manipulation and which plant components are involved in the process is still largely shrouded in mystery.

Hückelhoven's team of researchers has now succeeded in unraveling a part of the mystery. With the support of colleagues from Gatersleben, Gießen and Erlangen, the Weihenstephan scientists identified two proteins in barley that powdery mildew takes advantage of during its "hostile takeover" of living plant cells. Together, the two protein substances steer development processes in the plant cell. In barley, for instance, they are responsible for the growth of root hairs. The one protein, called RACB, is a molecular switch, which reacts to signals from outside to initiate a structural and metabolic response in the plant cells. In particular, it is involved in enlarging the plant cell surface during the growth process. The other protein, called MAGAP1, serves as its counterpart and can prevent or locally limit these activities in the cell.

The researchers observed just how the RACB protein supported the fungus during plant in-growth. A basic function of the protein, increasing the surface of the plant cell membranes, provides a gateway for attack: RACB fosters the increase in cell surface while the mildew is invading, thereby leaving the plant cell intact while still supporting the fungus. Hückelhoven's team was able to demonstrate that the plant becomes less susceptible to powdery mildew when the protein is missing. Hückelhoven explains: "That is how the fungus benefits from this barley protein. RACB makes it easier for powdery mildew to push its haustoria, or feeding organs, into the attacked cell, to then take control of the barley cell." The scientists suspect that the fungus manages to take control of the plant's signal chain from outside -- remotely, so to speak -- to open the door to the plant's nutrients.

The TUM researchers showed that barley is not entirely defenseless against this trick: MAGAP1 can effectively prevent such attacks from outside. This counterpart protein is normally found at the cytoskeleton of the plant cell, a dynamic network of protein fibers that is responsible, among other things, for reinforcing the cell wall to prevent fungal invasions. During an attack MAGAP1 migrates to the cell surface membrane where it then switches off the susceptibility factor RACB. This hinders the increase in cell surface, which the fungus needs to penetrate into the cell. The resilient barley cell may use this mechanism to slam the door in the face of powdery mildew.

The Chair of Pythopathology primarily does basic research. The scientists though, who are also members of the Hans Eisenmann Center of Agricultural Science at the TUM, had farmers in mind even at this early stage. "With a better understanding of the cause of diseases we hope, in the midterm, to find innovative approaches to maintaining the health of crops and grains by enhancing their immunity," says Prof. Hückelhoven.

 

[MIway]

I can't rep you at the moment... ;-)


But this is what you warn our community about re the PM... it's just a matter of time.

Scary to think, but the micro-world is much better at surviving than we are smart.

 

[joeca1i]

Can't they just breed a stronger apple,not a gmo apple,just a strong fungus proof apple seed.

 

[cannabeans]

this had been going on for many years...

and not just with apples!!!
monsanto the wonderful creator of " round up ready" and the creator of round up. hmmmm lets take a better look into this. this company has been genetically modifying FOOD CROPS IN AMERICA for A LONG TIME. chances are if you drink any soda pop, or eat ANYTHING that has HIGH FRUCTOSE CORN SYRUP, you most certainly have been injesting round up ready corn! with the creation of the "FOOD CROPS" that are resistant to round up, also creates through "over spraying", round up ready weeds!hmmmm so over time this chemical that has been sprayed over the corn, and many other food crops as well, are making the "weeds" that they were "designed" to KILL resistant to the spray.... what to do then??? well, guess what? you quessed it. MONSANTO now has an even STRONGER CHEMICAL THAT THAY WILL SELL YOU.

this is a vicious cycle! the stronger the chemical the stronger the resistance! this will continue to happen untill the american people wake up and realize that the "processed" food,and most of the fresh veggies they buy is straight POISON.

AND THE GOVERNMENT SUBSIDISES THESE "GMO" FARMERS.
THIS LENDS ME TO ASK THE QUESTION?

WHO IS WORKING FOR WHO?

GROW ORGANIC!!! AND STOP THE BOBMARDMENT OF CHEMICALS INTO THE HUMAN FOOD SUPPLY!

 

[cannabeans]

The worlds largest human experiment: GMOs, Roundup and the Monsanto monstrosity

 

[mastacheeser]

to bad marijuana growing is illegal, ill bet they could find some good advice from thcfarmers

 

[Seamaiden]

I can't rep you at the moment... ;-)


But this is what you warn our community about re the PM... it's just a matter of time.

Scary to think, but the micro-world is much better at surviving than we are smart.

I want to warn the community about all diseases and pests and what we, as a community, may be doing to foment ignorance in our communities and resistance in microbes.

and not just with apples!!!
monsanto the wonderful creator of " round up ready" and the creator of round up. hmmmm lets take a better look into this. this company has been genetically modifying FOOD CROPS IN AMERICA for A LONG TIME. chances are if you drink any soda pop, or eat ANYTHING that has HIGH FRUCTOSE CORN SYRUP, you most certainly have been injesting round up ready corn! with the creation of the "FOOD CROPS" that are resistant to round up, also creates through "over spraying", round up ready weeds!

But wait, there's more! If you eat beef or pork from the market, chances are those animals were fed with GMO corn and soy. And what does that matter? Until you learn what glyphosate seems to be causing and the fact that reduced fertility and disease in plants is being caused by ONE organism, and that organism is of a type that has never before been described by science.

hmmmm so over time this chemical that has been sprayed over the corn, and many other food crops as well, are making the "weeds" that they were "designed" to KILL resistant to the spray.... what to do then??? well, guess what? you quessed it. MONSANTO now has an even STRONGER CHEMICAL THAT THAY WILL SELL YOU.

Oh, exactly. You're hip to what's going on. And now we have California's Hemp Farming bill that just passed, which will lead to the chimeric marriage of big ag with big pharma.

this is a vicious cycle! the stronger the chemical the stronger the resistance! this will continue to happen untill the american people wake up and realize that the "processed" food,and most of the fresh veggies they buy is straight POISON.

AND THE GOVERNMENT SUBSIDISES THESE "GMO" FARMERS.
THIS LENDS ME TO ASK THE QUESTION?

WHO IS WORKING FOR WHO?

GROW ORGANIC!!! AND STOP THE BOBMARDMENT OF CHEMICALS INTO THE HUMAN FOOD SUPPLY!

PREACH IT!!! I'm on this train. I'm digging out poison oak by hand so that I don't use Round-up or anything related to it. I'm preaching it to people in my county and area. I'm preaching it wherever I go.

TESTIFY! Nature already put mechanisms in place that work wonderfully, and will work wonderfully for us, if only we start thinking ahead and not in terms of shortcuts. This is like diet pills.