As described in the link below asexual spores, such as the ones that are transmitted by wind, rain and dust to infect tomato and potato plants don't overwinter, but if both A1 and A2 genotypes of LB are present there can be sexual formation of oospores and they can over winter in freezing soils.

Just how many years they can stay viable is not currently known as the article points out.

Carolyn

Here is a link that might be useful: Oospores Can Overwinter

Can they be killed by soaking in bleach solution?

Carolyn

Let me see if I understand this process. Late Blight occurs if two "mating spores", A1 and A2, join to create the LB oospore -- which expresses the disease itself. And if only one of the mating spores is present, that's when freezing may kill the disease? Or just the spore that's present since the disease would not exist? Would you even know that a plant had one of the mating spores if one of them were absent? No plant symptoms?

If this is correct, I can understand that the full-blown disease would NOT be destroyed by freezing weather. Is solarization the only non-chemical way to destroy it? And anti-fungal sprays applied all season long from the get-go?

Are your plants surviving so far? (You mentioned in another thread that you were worried.)

=====
colokid, what would you soak in a bleach solution? The plant parts? It would probably kill the disease but anything more than one plant would be quite a job. And you'd still have the soil infection to contend with.

====
Well, it appears that Early Blight spores and the Alternaria pathogen are NOT killed by freezing either. [The information is visible in a search but not in the research summaries given, so I can't post a link.]

So I suppose if these two diseases end up in the soil, for my situation (no Late Blight so far) that probably means solarization. And then constant antifungal spraying of the plants next year. Sigh.

Second thought here.

If you were wondering about killing the blight spores on your plants, save yourself some trouble. Just put them in a clear plastic bag with some water to dampen them if they're dead and dry, and then set them somewhere out of sight in the sun. The heat will kill everything in the bag! Black plastic is okay, too, just doesn't work as fast.

Bleach:
No, I am thinking about soaking my entire garden patch with bleach solution..like a hundred gal. or so through my drip system. To kill the soil infection. After a good surface cleanup. Cheaper than buying a new lot.

"Let me see if I understand this process. Late Blight occurs if two "mating spores", A1 and A2, join to create the LB oospore -- which expresses the disease itself. And if only one of the mating spores is present, that's when freezing may kill the disease? Or just the spore that's present since the disease would not exist? Would you even know that a plant had one of the mating spores if one of them were absent? No plant symptoms?"

The spores multiply asexually and that is what you see currently in the northeast. YES, there are symptoms. And freezing will kill them.

But if the spores multiply sexually, (both M & F), then it is like a "super-outbreak," almost unstoppable, and freezing won't work.

That's my understanding from the last LB FAQ from 7/20/09...

Let me see if I understand this process. Late Blight occurs if two "mating spores", A1 and A2, join to create the LB oospore -- which expresses the disease itself. And if only one of the mating spores is present, that's when freezing may kill the disease? Or just the spore that's present since the disease would not exist? Would you even know that a plant had one of the mating spores if one of them were absent? No plant symptoms?

If this is correct, I can understand that the full-blown disease would NOT be destroyed by freezing weather. Is solarization the only non-chemical way to destroy it? And anti-fungal sprays applied all season long from the get-go?

Are your plants surviving so far? (You mentioned in another thread that you were worried.)

Fungi can exist in two forms, a vegetative form as seen on moldy fruit, at the top of fermentation containers and all over the place, and also as spores if it's a spore former.

Sexual mating of LB occurs not between spores, b'c that can't happen, rather, the sexual mating occurs between A1 and A2 vegetative forms of P. infestans that happen to be growing on the same plant or nearby.

My information says that the A1 and A2 spores do not over winter in soils that freeze but the sexual spores, oospores can and do.

if either A1 or A2 infects a tomato or potato plant you get the typical disease Late Blight. And no, you wouldn't have a clue as to what genotype you have, A1 alone, A2 alone or A1 and A2 together on your plants.

Spores are very hardy and I doubt that solarization or treating with bleach would inactivate them, but I have no data on that. I haven't googled the exact specs of LB spores but most of them, especially from bacteria, can only be killed by heating at high heat and high pressure as is done with foods to inactivate Clostridium botulinum spores.

Maybe I can find some specs on LB spores but I don't have time now.

Daconil sprayed all season I think is the best way to go b'c the active ingredient attaches to the specific sites on the leaf surface where spores specifically attach and blocks spore attachment. it also helps with the foliage diseases Early Blight and Septoria Leaf Spot.

I'm also having Freda alternate Daconil with Bonide copper b'c it's a good idea to alternate stuff and also b'c the Bonide copper works best against the baterial foliage pathogens whereas Daconil cannot/

As of 2 days ago my plants were LB free, only a bit of Septoria Leaf Spot and some Bacterial Speck, but there's no way that Freda can get out there to spray when we have rain almost every day and I can't expect her to come up here every day just to do that for something that will be washed off by the rain every day.

In a post here at GW this AM someone in the Albany area, just an hour south of me now has LB plants, so fingers crossed.

Carolyn

colokid -
Bleach administered in that way will NOT kill the fungi. The soil will neutralize the bleach, unless you administer thousands of gallons of it - and that's a superfund site in your future.

It takes specific climate conditions for the always-present blight to become epidemic ... abnormally cool and wet. Wet exposed soil, wet leaves, lots of water spashing around.

Quote from Carolyn:
"I'm also having Freda alternate Daconil with Bonide copper b'c it's a good idea to alternate stuff"

If I remember correctly, mulio said something similar about spraying only with chlorothalonil, that it could cause problems. Could someone please explain?

If I remember correctly, mulio said something similar about spraying only with chlorothalonil, that it could cause problems. Could someone please explain?

*****

It's not uncommon to alternate spray products to lessen the chance that mutations don't appear that make a product non-effective.

I'm not aware that tomatoes or potatoes have become tolerant of Daconil, for the home grower that is, b'c commercial farmers have Tatoo and Bravo ( daconil products they can use) but I'm also not that up to date on what larger commercial farms are doing about it.

I'm alternating with the copper simply b'c Daconil is the best for LAte Blight and fungal foliage pathogens and copper is best for bacterial foliage diseases and has low to moderate activity against fungal ones.

Carolyn

Alternating products will dramatically reduce the chances of strains of the organisms developing resistance. Can you say "Fungal MRSA" boys and girls?

Its very simple. If you are going to spray fungicides, it is completely irresponsible not to use at least two different products. If you are not going to do this, then don't spray anything at all.

Alternating products will dramatically reduce the chances of strains of the organisms developing resistance. Can you say "Fungal MRSA" boys and girls?

****

John, I spoke to that in my post just above yours, but MRSA? Whew, I dunno about that. LOL

(Its very simple. If you are going to spray fungicides, it is completely irresponsible not to use at least two different products. If you are not going to do this, then don't spray anything at all.)

I don't think I can agree with your comment about not spraying at all unless two alternating products are used. Yes, it's preferable to use two, as I also wrote above and as did mulio, but I don't think that using just one is all that bad if that's allthat someone has available to them.

Through this Late BLight crisis we have here in the NE I can tell you that many normal sources for Daconil, copper, mancozeb, maneb, etc., are out of stock. New shipments of some are supposed to be arriving, per the remarks of others who have posted that online and it was also true where I live, but my local Agway was able to get what I wanted, but I had to wait quite a bit.

Given a choice for those of us here in the NE who are in the target area for Late Blight right now, if only ONE product is available to someone I'd try and get Daconil.

Late Blight is lethal, so I suggest getting that Daconil and using it. Just over the weekend I saw folks an hour to my south who posted pictures of their LB plants and since many local folks here where I live don't even know about the current LB problem I have no idea what spores might be wafting over my propert right now. Sigh.

Carolyn,hoping that Freda gets here today to spray my plants for me b'c we're behind on th\je spray schedule.

Please check out the following link which is an update of 7/20 from Cornell.

Check out the LB Faq's and Correction of wrong information from the left hand side of the page.

Most important is the fact that only one mating type is found here in the NE and that the sexual oospores have not been found here in the NE and that the fungus can only exist, then, on living tissue.

Carolyn

Here is a link that might be useful: Cornell Update

Carolyn

Does the new information mean that this plague in its current form won't survive in the soil over the winter if the ground freezes?

t wasnt me who posted but I also am also aprox 1hr north of Albany ny In Lake Luzerne. I lost 25 Tomato plants and 6 Potatos All my plants.
I asked the guy at the Farmers market (Master Gardeners Program )the same question about it staying in the soil he couldent answer it . He said he would find out for me I will go back next saturday and will post results here.
I am on a 4 year rotation where I plant so I probbably will be ok but I did want to know the answer.
Regards Scott

According to the guy I talked to it will not stay in the soil. But im not taking any chances I have been expanding my garden every year and currently am on a 4 year rotation for crops.
This sucks loosing all mine some freinds from Corinth said they would take cuttings from theirs and pot them so I could put them in my Hoophouse Greenhouse. I figgured I might get some come septLOL. Now they are pulling all theirs also.
Carolyn beware it all around ya N S E& W. Hope ya remain LB free
Regards Scott