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Brown Leaves / Fungus?


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#1 psalingue

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Posted 16 June 2004 - 07:29 AM

We have been having a lot of rain and LOTS of humidity here in my part of Oklahoma lately. I noticed that some of the leaves on my 1 year old Chambourcin and few on my 1 year old Traminette are developing brown spots and then the whole leave turns redish brown. Does anyone have any idea what is happening. I thought it might be black rot or some other fungus. Any help or suggestions on how to treat are greatly appreciated.

phil





#2 VCV

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Posted 16 June 2004 - 08:23 AM

The redding of the leaves looks virus related to me.

#3 psalingue

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Posted 16 June 2004 - 09:22 AM

VCV,

When you say virus are you thinking in the line of Pierces'? The brown spots strart small and then eventually take over the whole leaf causing it to turn that redish brown.

Thanks.

phil

#4 VCV

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Posted 16 June 2004 - 01:55 PM

I am not familiar with pierces disease, I have never had to deal with it because the insect that causes it cannot live up here KNOCK*3.

I do not know if pierces disease is in fact considered a virus. And i do not know the symptoms of the disease. I wish I could help you there.

However, it is my understanding that viruses are very common among varieties that have not been through FMPS treatment. Some viruses actually improve fruit and yield, some kill vines. It is also my understanding that some viruses can cause leaf coloration similar to what you are showing. They can also cause leaves to show other colors such as chrome and black and white.

The vines of mine that looked like yours, died the following year. I do not know why exactly. It could have been crown gall, overcropping, insufficient carbohydrates, trunk damage, or a virus. Normally when I see flamboyant colored leaves I assume it is a virus. Although the vines of mine that died were extremely overcropped the previous year. Maybe there is a connection there.

There might be something going on below ground as well.

If that is in fact a virus, there is no cure once the vine is planted. I would cut all the fruit off that vine and hope for the best.

(all of this is intended...... unless there is evidence of downy mildew that I cannot see through this cheap monitor)

Good luck - J

#5 Draftsman28

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Posted 16 June 2004 - 02:16 PM

I read somewhere that mineral deficiencies can cause leaves to turn colors. Magnesium, boran, nitrogen any of that sound familar?

#6 Brad B.

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Posted 16 June 2004 - 05:53 PM

Looks a little like leafroll virus though I'm no expert.
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#7 Hippie

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Posted 16 June 2004 - 07:41 PM

Probably from too much water.
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#8 psalingue

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Posted 17 June 2004 - 07:27 AM

I suppose leafroll is a possiblity. Anything I have been able to find on leafroll talks about the leaves changing color prematurely, but closer to late summer. Still, it's a posibility.

The last few days things have dried out a bit and I haven't noticed many new 'damaged' leaves.

I hadn't heard of leafroll but here is a link to some good shots of symptomatic signs.

Texas Winegrape Network

I guess I will just keep a close eye on things for the next few weeks and see if there are any more problems or distinguishing features that can help me identify the source. If the problems go away when things really dry out (which always happens here), the to much water theory might be on target.

Thanks again for all the input.

phil

#9 VCV

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Posted 17 June 2004 - 07:47 AM

There really is no such thing as "too much rain". (Climates incapable of producing grapes notwithstanding.) Unless your vines are sitting in an area with poor drainage and the roots are rotting.
There are however, various mildews and diseases that can be stimulated by rainfall, dew, and humidity. I do not see evidence of these in you photo.

#10 Hippie

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Posted 17 June 2004 - 06:30 PM

VCV, maybe in Northern Michigan you have never had too much rain. In OK and AR, one thunderstorm can produce up to a foot of rain in an hour or 2. Even a moderate thunderstorm producing 3 inches of rain in 30 minutes can cause harm because of plants standing in water for a day or so. Also, this can happen everyday for a few days this time of year in the south. That would be too much rain.
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#11 VCV

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Posted 17 June 2004 - 07:21 PM

Thanks Glenvall, it sounds like it rains alot harder down in your area then it does up here. An inch an hour is alot of rain for us. But it never lasts more than a few hours.

I was assuming that phil's vines are not sitting in standing water, as he did not mention anything about flooding. In addition, with regards to too much rain, I assume one would take a climate in to consideration when planting vines, whereas they would not be planted in an area prone to accumulating standing water for more than briefly; and therefor would escape the throes of "too much rain". But, it sounds like what you call 'too much rain' is what we northern boys might call, "vines planted in the wrong place."

Thanks

#12 psalingue

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Posted 18 June 2004 - 07:08 AM

Standing in water is not the problem. The vines are on a nice hill with good run off of the water. I am from Michigan myself originally, near Grand Rapids, so I know about the weather up there. I thought the lakes put off some high humidity, which they do, but down here it is just insane. I suppose that's what contributes to the frequency and severity of tornados and storms here every spring. I am starting to think more and more that this is related to the problems that the humidity can bring so I am going to increase the frequency a bit of spraying fungicide. We'll see how it goes.

I only hope that my choice of vines for this area wasn't such a bad one that I have to go with something else.

Again, I appreciate the input.

phil

#13 VCV

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Posted 18 June 2004 - 10:34 AM

"..... so I am going to increase the frequency a bit of spraying fungicide."

That is what I did not want to hear. This typicality is exactly why I am so adamant about correctly identifying pests and diseases, and other problems. I hate see people over-spraying because they have not correctly identifyed the problem which, often times will not be controlled with a broad spectrum fungicide. Unless you have discovered mildew, a fungicide will not solve your problem. You should look into a possible virus or, as Draftsman mentioned, a mineral deficiancy.

You may also want to confer with the thread that JDM started with links to photographs to downy mildew.

Regardless, the definition of Integrated Pest Management begins with proper identification.




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