a talk with a farmer, LB cure

[carolyn137]

Responses for both Heather and Mark

Originally Posted by hasshoes

Cool info.

I'd really like to know what tests Serenade goes through to be able to list as "controls or suppresses" Late Blight.

I have an ongoing joke with a friend about this that I won't post here.

Heather, actual challenge experiments are done with a known number of spores to determine the efficacy of any such products. it isn't a matter of just noting what does and doesn't work in a field situation where there might be, could be, some LB spores around.

The same thing is true, that is, controlled challenge experiments, in order for a specific tomato variety to have any of the alphabetical notations after the variety name, such as VFNT in different combos, etc.

Mark, good information, but folks should realize that many of the products noted are not available to the home grower. Even Bravo, which is a higher concentration of chlorothalonil, is not available in most states without a pesticide license, which is true of almost all the other products mentioned.

We home growers have Chlorothalonil ( 29.6% in the concentrate), Mancozeb, in some states, but not all, and copper sprays.

I noted Tom Zitter's name there. I've talked to him several times in the past and he's a terrific tomato pathologist but our talks revolved around what I ended up calling the CRUD and he suggested at the time that it was an aberrant form of Early Blight ( A. solani), but I've heard nothing more about that and he said at the time that they couldn't prove it.

[hasshoes]

But do they do the tests under conditions ideal for late blight to flourish?

I would like to know if the spores were introduced when it was 80 and sunny with a gentle breeze . . . or during eight hours of cold, wet, dampness.

;0) ;0) ;0)

[carolyn137]

Originally Posted by hasshoes

But do they do the tests under conditions ideal for late blight to flourish?

I would like to know if the spores were introduced when it was 80 and sunny with a gentle breeze . . . or during eight hours of cold, wet, dampness.

;0) ;0) ;0)

I would assume so Heather in terms of favorable conditions when testing for the various products used for either prevention, or cure of LB, as Mark posted above.

To do challenge experiments when it's sunny and warm would be somewhat meaningless as I see it in terms of developing and assessing products to be used for LB.

I know there are different protocols for challenge experiments but I'm not privy to the specifics and I don't think anyone is other than those doing the challenges to get the data that Mark posted.

[mjc]

Originally Posted by carolyn137

To do challenge experiments when it's sunny and warm would be somewhat meaningless as I see it in terms of developing and assessing products to be used for LB.

Unless, the experiment is to see the effect of sunny/warm on LB...which is somewhat pointless, as the weather isn't a 'product'. But, as we know, it does have a profound impact on LB and other diseases.

[hasshoes]

I guess I'm just trying to understand how Serenade gets to list Late Blight suppression on it's label. :-)

[carolyn137]

Originally Posted by hasshoes

I guess I'm just trying to understand how Serenade gets to list Late Blight suppression on it's label. :-)

http://bioengr.ag.utk.edu/Extension/...ate_blight.htm

Heather, I have no idea how Serenade gets listed for Late Blight suppression.

The above link presents data to show that plants treated with Serenade for LB were no different than NO treatment at all.

And Mark's data said only 2-4% suppression which makes it almost worthless to use IMO.

There are lots of Google links, I chose just one, and maybe you can find out more by Googling or even contact the folks that make Serenade and point out what you've read in this and other threads about LB here and elsewhere and ask them where the data is that says it supresses it and most importantly to what DEGREE does it surpress.

They may not even know since, I can't be sure, b'c it's usually University studies that present the data. But it seems to me if they're listing it they should know something.

Looking at a lot of threads at several places I think what it comes down to is that some folks would like to stay organic in fighting LB, but everything posted so far says there is nothing organic that works very well.

I would prefer to stay organic myself, as I've said here several times, but if it means losing all my tomatoes then I will and am using Daconil, alternating with copper, knowing Daconil has less toxicity that does organic Rotenone and knowing that it can be sprayed to the day of harvest also tells me something as well.

[bboomer]

Originally Posted by carolyn137

Responses for both Heather and Mark



Heather, actual challenge experiments are done with a known number of spores to determine the efficacy of any such products. it isn't a matter of just noting what does and doesn't work in a field situation where there might be, could be, some LB spores around.

The same thing is true, that is, controlled challenge experiments, in order for a specific tomato variety to have any of the alphabetical notations after the variety name, such as VFNT in different combos, etc.

Mark, good information, but folks should realize that many of the products noted are not available to the home grower. Even Bravo, which is a higher concentration of chlorothalonil, is not available in most states without a pesticide license, which is true of almost all the other products mentioned.

We home growers have Chlorothalonil ( 29.6% in the concentrate), Mancozeb, in some states, but not all, and copper sprays.

I noted Tom Zitter's name there. I've talked to him several times in the past and he's a terrific tomato pathologist but our talks revolved around what I ended up calling the CRUD and he suggested at the time that it was an aberrant form of Early Blight ( A. solani), but I've heard nothing more about that and he said at the time that they couldn't prove it.

Hi Carolyn,
Is there any hope for an organic cure or prevention of LB? I do not use ANY herbicides or pesticides in my garden and I don't want to start. But then I did raise my plants from seed....
Just sign me,
Depressed in Wisconsin

[hasshoes]

Copper is organic and while not a cure once the plant gets hit, it *can* work as a preventative.

Even though it's organic I guess it can kill fish or something, unfortunately.

[dice]

The usual issue with copper compounds is that they build up
in the soil over time. Using it one season, you are probably ok,
but using it year after year on plants in the same beds is a bad
idea. You get an oversupply of copper, and it interferes with
the uptake of other nutrients (in addition to any negative
effects from it leaching into the local aquifers, etc).

[amideutch]

Unless the land you are growing your tomatoes on has been used for agriculture for a long time I wouldn't worry about soil contamination. Normally copper becomes fixed in the first 6 to 8 inches of soil so it leaching into the aquifers is rare. As the copper is used as a foliar for antifungal applications I wouldn't worry to much as long as you follow the application rates. Bonide Copper Fungicide has a copper equivalent of 1.8%. So with the application rate is 0.5-2.0 fluid ounces per gallon of water the copper content is quite low when applied to the plant and what ever is absorbed by the soil.
Fact: One of the first chemical sprays used to kill weeds was a 5 percent solution of copper sulfate. Ami