Late blight and mycorrhizae

[Marko]

This season I'm using mycorrhizae for the first time. On the packet is a statement that mycorrhizae promote resistance against Pythium, Phytophthora, Verticillium, Agrobacterium tumefaciens, Meloidogyne spp. and Pratylenchus spp.
I simply can't believe that mycorrhizae can work against Phytophthora. It's so devastating disease that's hard to me to believe that it can be prevented so easily.
But on the other hand I still have healthy tomatoes with no sign of LB, which is very unusual for mid september in Slovenia. Perhaps this year I'll brake the record and have tomatoes till the first frost.
I wonder if any of you have personal experience with mycorrhizae and Late blight?

[carolyn137]

Originally Posted by Marko

This season I'm using mycorrhizae for the first time. On the packet is a statement that mycorrhizae promote resistance against Pythium, Phytophthora, Verticillium, Agrobacterium tumefaciens, Meloidogyne spp. and Pratylenchus spp.
I simply can't believe that mycorrhizae can work against Phytophthora. It's so devastating disease that's hard to me to believe that it can be prevented so easily.
But on the other hand I still have healthy tomatoes with no sign of LB, which is very unusual for mid september in Slovenia. Perhaps this year I'll brake the record and have tomatoes till the first frost.
I wonder if any of you have personal experience with mycorrhizae and Late blight?

Marko, I also have problems with several of the other pathogens listed there which are supposed to "promote resistance" b'c almost all of them are soilborne diseases but Late Blight, P. infestans, is not. it's acquired via air and embedded in rain droplets.

And the fact that you have no LB to date doesn't surprise me either since not every year are the spores around and many who had LB here two years ago in that huge outbreak here in the NE have not seen it again.

Mycos are supposed to increase water uptake and I forget which mineral, maybe Ca++, I didn't check, but I can't see them promoting resistance to ANY disease b/c to be honest there is NO disease that any tomato variety is resistant to as I see it. Maybe tolerance with some of the hybrids where genes for certain diseases are bred in, And maybe some OP's with tolerance as well, but that's about it.

And I sure was suprised to see Root Knot Nematodes on that list as well, and although they didn't mention the Northern or Southern ones, my bet is that they wanted folks to believe is was the Southern ones which can and are a major problem here and in other countries as well according to where tomatoes are grown, in a goegraphic sense as well as soil composition.

Nope, no experience here with mycos at all ever since reading about the supposed effect on just tomato growth in the late 90's where controls were done and little to no difference seen with and without mycos.

[amideutch]

Marko, What company did you purchase the myco from and what species did it consist of. Ami

[RayR]

There are many species of Phytophthora, many of which are root rot pathogens that are specific to various plant species. Phytophthora infestans is the Late Blight that attacks tomato and other nightshade family plants, but it is for the most part a airborne pathogen that attacks the above ground parts of the plant. I suppose there are mycorrhizae that can protect the roots of some plant species against some Phytophthora root rots, but I don't see how they could be effective at combating Late Blight on tomatoes.

[amideutch]

Here are a few links that might be of interest. Ami

http://joas.agrif.bg.ac.rs/sites/joa...090402251o.pdf

http://journal-phytology.com/article/viewFile/4473/2207

[Marko]

Thanks for answers, I was obviously wrong when I assumed that Phytophthora is only Late blight. In the second link of Ami it's clearly stated that mycorrhizae protects the plant against Phytophthora parasitica.

Ami, here you can find info about this product: http://www.micosat.it/The-product:-Micosat-F/

I'm satisfied with it, especially on eggplants. They allways had some sort of wilt, no wilt this year.

[carolyn137]

Marko, yes, there are many species of Phytopthera that can cause problems for tomatoes other than P. infestans and I think that the various species that are involved with damping off are perhaps some of the most important along with the two other genera and species also involved in damping off.

But Late Blight is really quite different from the others in terms of transmission and of course symptoms and outcome for the plants infected.

[amideutch]

Marko, as you have read in the documents myco's can enhance the plants defense mechanisms and vitality which help it better deal with pathogen attacks. Another article I read the other day showed a study that tomato plants grown with organic ferts versus chemical (especially nitrogen ) had higher resistance to phytophthora infestans by as much as 40%.
Your best bet for next year besides the myco's and organic ferts would be Azoxystrobin which I have had very good results with. Ami

[RayR]

Ami, I've read about Azoxystrobin before, but every product I've seen was pretty pricey and/or in large quantity for large scale use. What Azoxystrobin product are you using?

[amideutch]

Ray, I know how pricey it is as I have checked it out stateside and it seems to be geared for commercial growers and not home growers. I use the Neudorff product and even e-mailed the North American distributor and no joy. Here is a link to what I use. Ami

http://www.neudorff.de/produkte/kata...-pilzfrei.html

[Marko]

Ami thanks for the info about Neudorff's Azoxystrobin. Neudorff's products are available here so it should be no problem getting it.

[amideutch]

With Azoxystrobin limit your applications to no more than 5-6 during the entire season. For the product shown from Neudorff I pay 10 euro. Ami