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late blight: advice?

 
Leila Rich
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I've been away from my garden for nearly a month. When I was away I id' someone's tomatoes as having late blight and we disposed of them. I've never seen it before, but online photos matched the symptoms: brown blotches on the stems and leaves, with leaves going crispy and dying.
When I arrived home today, I raced ou to check out the jungle and my tomato plants have the same thing
I'm taking a sample to get id' tomorrow, but am fully prepared to pull the lot asap. What's really freaking me out though is the potatoes. They're everywhere
and I really can't imagine getting them all out, especially as the garden looks like this!

I didn't take any photos of the suspected blight which was silly, but I'm pretty sure that's what it is.
I really can't imagine what to do. I have no idea how long the blight's been on the plants, but judging by the state of some of them, it's a while.
The potatoes still look fine, but I suppose they'll be next.
Has anyone got any advice about dealing with this disease?
 
Ken Peavey
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Cool, damp, and enclosed space seem to promote it. Increasing airflow around the plants will help. Cut off those lower leaves and branches. It will help dry out the plant and open it up, Keep a close watch when weather conditions are right. Surgery can delay the effects for maybe a week if you remove infected parts as soon as you see them.
 
Leila Rich
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A plant person I trust says it's definitely late blight, probably with another fungus or two for good measure.
She recommended pulling the tomatoes and carefully disposing of the plants: they're too far gone to save and since my potatoes still look healthy, I'm going to try and keep them that way.
My garden's way too small to rotate for disease, so I might be looking at alternative tomato strategies for a couple of years...
As soon as the gale dies down, I'll be taking out the tomatoes and doing some major chop'n'drop!
 
Leila Rich
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Late Blight update...
The spuds got it too I bagged-up the vines, but left the tubers in as they're still largely unaffected and there's absolutely no way I could winkle them all out anyway.
A while ago there was a thread about the risks of viruses in a perennial potato ployculture and I decided to let them 'do their thing'.
I didn't factor in crazy fungus though!
When I can grow them again (please let it be next season), my potatoes won't be free-range, that's for sure.
If anyone's got any suggestions for tasty, LB-resistant potatoes, please let me know.
 
Ken Peavey
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I've had run ins with Late Blight before. It's a tough one.

The lifeform that causes the infection is P. Infestans. While it is referred to as a fungus, it is not a fungus. Or a virus. Or a bacteria. It is an Oomycete. Kind of a rogue lifeform in a classification all to itself. It reproduces with spores and has some similar behavior to fungi, which is why it is usually referred to as a fungi. It is indigenous to all soils on the planet. There is no getting away from it. You can burn the infected plants, but it remains in the soil. You can solarize the soil, but it will be a few feet away in soil that was not treated. The spores are produced in the kind of quantity that Carl Sagan can best describe, and they travel in the wind.

Treatment, according to just about every County Extension office is to use a copper based fungicide, and in no small amount, with repeated treatment. The fact is, once the conditions are right, this thing reproduces at such a rate that the most you can do is harvest what you can and move on. Organic control would be to use compost tea. This has the effect of populating leaves and stems with more traditional fungi and bacteria, leaving less room for P. Infestans. It helps, but just a little. If the conditions are right, it's like trying to stop a freight train with a lasso. Physical control would be removing leaves. The effect here is to gain time for fruit to ripen, allowing harvest.

Even when the fruit or tubers are harvested, they can still be destroyed. Late Blight was the cause of the Irish Potato famine. Even though the tubers had been harvested, they rotted in storage. I've seen this firsthand. The potatoes look fine, have been washed, properly stored, and checked upon every other day. Nonetheless, they turn to mush in a couple of days. Monday has a perfect looking potato, Tuesday it has just the slightest grey/brownish area, Wednesday it is mush. The most accurate image I can offer as to the appearance and consistency of this mush is booger snot. Tomatoes turn grey/brown and shrivel, also in just a few days.

This thing primarily attacks solanacia crops: tomato, potato, and supposedly eggplant and peppers. I've not seen it on eggplant and peppers. They tend to ripen during the heat of summer, which is a less suitable environment for P Infestans. Also, the structure of the plant is more open and airy which is less conducive for growth of the pest.

I hate to bear bad news, but those potatoes in the ground don't have much chance. Once the plant is infected, the spread is so rapid that no part of the plant survives. By the time you see the infection on the plant, it has already spread through the plant. Chances are those spuds are already gone. You can try to dig some up. If you find some, wash them, dry them, consume them immediately. You can store them in a cool dry area, but in all honesty, they will turn to mush in a week.

This thing has killed millions of people. Not directly as it is harmless to humans. Instead, it destroys the crops, with potatoes at the top of the list. It is the calories destroyed that starves the people. In 2009 an infestation destroyed tomatoes and potatoes in 17 US states along the east coast and the northeast. You could not find a tomato or potato at a farmers market in NY that year. I lost 300 tomato plants, 600 potatoes. From detection of the first infected plant to the death of the last plant was less than 2 weeks. I managed to harvest about 200 pounds of potatoes, at least half of them rotted within a week. The blue potaotes, Purple Viking, held out the longest.
 
Ken Peavey
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Phytophthora Infestans
 
Leila Rich
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Thanks Ken; I'm not usually loose with my classications and should've taken the opportunity to type 'oomycete', which is a very cool word!
Yip, I think I'm stuffed. I bought some copper, but it's just sitting there. I won't be spraying poison round in the most likely vain hope of slowing it down
I guess it's no spuds/toms next season.
 
Julie Helms
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I have had it here in Pennsylvania on my tomatoes for the last two years. Two years ago it wiped out everything before I got any fruit. Last year I sprayed the plants with diluted milk several times (http://www.self-reliance-works.com/2011/07/growing-tomatoes-fighting-blight/) and was able to harvest about half dozen fruits from each plant before total wipe out. I had also grown them in 3 different locations on my property in 3 different types of soil (compost, dirt, potting soil out of a bag). The potting soil one was the last to succumb but it did eventually.

I was feeling really badly that I must be the only person on the earth who can't grow a simple thing like a tomato.

Thanks for the info.
 
Leila Rich
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Julie, I don't think growing tomatoes is a "simple thing" and they're by far my most demanding plants.
Ken's post confirms that aside from a bit of cultural stuff, it's out of our control. Leaving the garden for a month at the height of the season was not a smart move though.
I'll try growing toms out the front next season, but I've got lead in my soil, so won't be trying any root crops!
 
Jason Long
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Here is one of paul's videos with Brian from inspiration farm. In the end, they talk about equisetum (horsetail) tea in regards to blight. Enjoy!



(finally figured out how to embed videos)
 
nancy sutton
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Thanks, Jason (and Paul :). Brian mentioned biodynamics, and as the end faded, it looked like he was describing a stirring technique, and I think the time and directions are important in biodynamics. Wonder what he was saying.... Now I'm wondering if the time of year that horsetail is harvested makes any difference. I'm pretty rich in horsetail :) Now, if only, morning glory and english ivy were as useful!
 
Alison Thomas
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Oh bums, looks like my tatties (potatoes to those not Scottish!) have got the dreaded lurgy. Little black spots on the leaves, a few plants looking collapsed. Sigh. It's been a wet year and loads of my stuff has succumbed to slug attack so I was glad to have a good potato harvest coming along. Now it's warm and wet, just ideal for blight. Ken, your 'helpful' post (yes it IS helpful but leaves one feeling glum) has made me all sad
 
Leila Rich
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Oh no Alison! A Scot without tatties is like a..I dunno, NZer without spuds
I actually saved my potatoes. I cut the vines at ground level and tried to spread mulch over the cut plants. Some tubers had already turned into stinking mush, but the blight didn't spread further.
I double-bagged the tomato and potato plants, let them stew in the sun for a couple of weeks, then sent them to the dump.
I'll generally do backflips to avoid dumping stuff, but I just wasn't going to risk it.
 
Judith Browning
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I might have missed this information in your thread, but I wondered if you select/save your own seed, grow your own plants , make your own potting soil? I found when I started doing all of those things my plants were much healthier and more disease free than when I brought in plants from other sources.
 
Alison Thomas
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I just read in a gardening magazine that the haulms can be composted as the blight only lives on live material. Hmmm thoughts? I'm about to remove all the nasty dead looking haulms today in my spare wellies, all clothes going into the wash once I'm finished, hands detoxed etc.

I also remember reading that there were two types of blight - an early one and a late one. The late one being the more devastating of the two. Anyone know anything about that?

I have another patch of potatoes that as yet are unaffected plus my tomatoes are just about to start producing and we eat LOTS of tomatoes. Please oh please don't let them get it.
 
Leila Rich
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Alison Freeth-Thomas wrote:I just read in a gardening magazine that the haulms can be composted as the blight only lives on live material

I'm pretty sure that is the case, but it freaked me out so much, I wanted the cooked mess far, far away
My compost's 'cold', so I can't rely on any bacterial heat to cook the...Oomycetes...
Definitely two types, and from what I know, late blight's waaay nastier. See Ken and his Irish potato famine.
I think I was extremely lucky, and while I lost all my toms, my spuds seeem to be ok.
Considering the nightmare I would have had trying to get them out from everywhere, I feel very, very relieved.
As for you plants that are still good, my advice is to avoid moving blighted plants around when it's windy, clear the patch a bit if it's overgrown (I think this, along with a wet summer was the major culprit for me) and be really scrupulous about cross-contamination. \
And cross your fingers!
 
Richard Nurac
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I have been growing tomatoes for several years and I am still trying to figure out the causes and the remedies.

I grew successfully in an Atlanta suburb for several years but was restricted by light considerations to just one area. And when the wilts and blights struck I concluded the problem was failure to rotate to new soil and so I relocated my growing operations 50 miles north of Atlanta where there is plenty of rotatable space. The local guru said to envelop the tomato stem 2" below and 3" above ground with aluminum foil, to remove the lower leaves, and to mulch to avoid rain splatter from the soil. Which I did for a few years until one very wet summer most all the plants turned black and died, though some varieties seemed to do better than others. This year I dispensed with the aluminum foil and have planted a number of different varieties and they are still doing fine though it is apparent that some varieties cope better. And we have not yet had protracted damp.

I wonder if the reason for the upward spread of the blight is because it originates from the soil lower down and so the lower leaves are first in proximity? Or is it because the lower leaves are older (less resilience) and also had longer exposure to the blight causing conditions?
 
Alison Thomas
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Well we cut off the entire plant above ground on the potatoes and currently the tubers are still fine. We've left them in the soil for the time being so that if any are blighted then the air can't move it onto any more.

The tomatoes now have 'something'. It's not moving anywhere near as rapidly as the blight on the potatoes (3 days there from noticing it to plant being totally blackened and dead), just the odd spot here and there. We too have removed the lower leaves and any that touch other plants or the side of the polytunnel (ours are 'indoors' not out in the open). Oddly it doesn't seem to be our lower leaves that are always the first affected.

Yesterday we sprayed with bicarb of soda/vegetable oil/castille soap/water mix and apparently have to do that every 5 to 7 days. I wasn't keen to use the Bordeaux mixture after discussing it here and on other bee forums. So we'll see how we go.
 
David Rogers
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Copper is not a poison, it is an essential nutrient. If plants don't have enough copper they cannot create the defenses for diseases.

Dave Rogers
 
Leila Rich
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I think it's pretty safe to say that the level of copper required to be an effective fungicide is poisonous, or it wouldn't work
As far as I know, copper is very hard on invertebrates, particularly worms.
Anything that kills my worms will need to work pretty hard to convince me I should use it!
 
Alison Thomas
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I was also concerned about the sulphur in the Bordeaux Mixture as it was sulphur that used to be used to kill the honey bees when folk wanted the skep honey.

And as for the copper bit - Tom's post on this thread
http://www.permies.com/t/16263/bees/Bordeaux-Mixture-safe-bees
made me decide not to use it...
 
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