Early Blight resistance.........

[Razorback04]

Is there such a thing? Early Blight has been an absolute plague here in the mid-south this year, so I thought I'd ask if there are certain varieties that are less susceptible to this evil plague. I've read about one called "Mountain" that supposedly has some resistance, but are there others?

For me, my Black Krims show some evidence of E.B., but are holding up much better than most others. The Shady Lady's seem extra susceptible to Early Blight while the Arkansas Travelers, Super Fantastics, and Glorys are about average. The German Johnsons are doing well, and I've heard that the potato leaved varieties normally fare well against E.B.

All of that VFFNTA stuff is great, but I want a tomato that says E.B. Resistant. (oh, and it has to taste great also)

So if anybody knows of any E.B. resistant tomatoes, fire away and give me a list.

[feldon30]

I'm sure Carolyn will weigh in as this is one of her favorite topics, but...

There is no such thing as an Early Blight resistant tomato that "tastes great". In fact as a non-farmer up until recently, it was not possible to buy seeds for the handful of varieties which show some EB tolerance/resistance. And realize that these tolerances only allow the plant to survive another 1-2 weeks longer than it otherwise would have. This is useful to a farmer for whom 1-2 additional tomatoes per plant times 10,000 is a huge difference, but what use it to a home gardener?

Johnny's sells seeds to the public of a hybrid variety JTO-99197 (F1) for $8.55 for 50 seeds. But before you run out and buy seeds of it, you might want to read the University of Missouri study on EB-tolerant tomato varieties.

All reports I have heard about the "Mountain" group of tomatoes (which were bred by scientists) is that they are flavorless and have thick skins and are pretty much indistinguishable from grocery store fare.


I'm going to assume you are applying an adequate layer of mulch of pine straw, pine bark, shredded newspaper, etc. of 4-6 inches and still having trouble.

Are you spraying your plants with either Daconil (chlorothanonil) or Serenade (an organic equivalent that some have reported success with)? Both are fungal preventatives that most people in the South and South East use in order to get a viable tomato crop.

Spray entire plants once per week from date of plant out until the end of the season or until tomatoes are no longer desired. Toxicity is relatively low and fruit can be picked the same day, washed, and eaten. The concentrate is greatly preferred to the ready-to-use not only for cost, but because it sticks better to the plants in rainstorms.


I have read your posts about growing watermelons with interest. I am curious how you grow watermelons without suffering major fungal problems. I would have assumed that you spray them weekly with Daconil or some other fungal preventative for anthracnose (fruit rot) and other foliar fungal diseases.

[carolyn137]

No such thing as resistance to ANY tomato disease the operative word being tolerance as now used in the tomato industry.

There are three varieties that have been bred to have minimal tolerance to EB. One is the one at Johnny's that Feldon just linked to, another is a release from Dr. Randy Gardner at NCSU and that one may well have a Mountain name since he's the hybridizer of the Mt series. And I've forgotten what the third one is.

But in talking with Randy about this here's what he said. He said that the tolerance is so minimal that it would be pretty much useless to the home gardener. it would only be of some possible usefulness to the large commercial farmer who could then spray maybe every 7-8 days instead of every maybe 4-5 days which would be a considerable cost savings to the farmer.

I think the better way to go is to start a rigorous spray schedule with Ortho Garden Disease Control, aka Daconil, right when you set the plants out.

I haven't heard that much feedback re Serenade and EB so can't really speak to that.

[Razorback04]

Okay, that's some really discouraging news, but I appreciate the replies anyway.

As for the mulch, that's a yes. Actually, I've experimented some with most of the different types of mulch that you mentioned......no noticeable differences so far. As for the Daconil, I sprayed it only twice and that was after I had first noticed some spots on the leaves. It seemed to briefly slow down the EB, but only barely. Why only twice? After a few web searches about Daconil turned up some scary info, I decided that it sounded more dangerous than the EB. I've since discovered that it's really, really hard to get good unbiased info on things like pesticides and fungicides. It seems that most folks are at one extreme or another. I finally decided to spray until the plants started producing fruit and then stop.

Even my tomatoes that were grown in ground that had not grown tomatoes for several years, eventually developed EB. The onset was later, so I'll still get a decent crop but it's definitely there.

Ahh, the watermelons. I have a few black spots on some of the crown leaves, but nothing that seems to have affected the vines in a major way. They are now on the verge of harvest, and the biggest problem that I have with them is the fact that we're now in a dry spell. Hopefully, that'll mean even sweeter than normal melons.

I'll try and post some pics in a day or 2..........Both of the EB and the melons.

[Suze]

Originally Posted by Razorback04

As for the Daconil, I sprayed it only twice and that was after I had first noticed some spots on the leaves. It seemed to briefly slow down the EB, but only barely.

Daconil is really best used as a preventative. It's not an antifungal per se; it works by 'sealing'/coating fungal attachment sites on plants. Can it have some effect when used after disease symptoms are apparent? Sure, especially if one removes visibly diseased foliage from the plants and disposes of it away from the garden area. But I've personally experienced vastly superior results from religiously using it early on in the season, even moreso than even bothering with it too much at all later in the season. In my case, too many plants to make it practical when they get huge anyway.

Another thing I've found helpful is to really stay on top of removing any diseased looking foliage when the plants are smaller, and also removing leaves below the first fruit set (I mostly remove just the leaves, and few, if any suckers).

[carolyn137]

After a few web searches about Daconil turned up some scary info, I decided that it sounded more dangerous than the EB.

*****

I suggest you access the data for all pesticides, fungicides, etc. at EXTOXNET which is a consortium of Universities, as you'll see, and that's where you'll get unbiased information.

Daconil is the most widely used fungicide in the world and so plenty of data exists.

When you see that something can be applied up to the day of harvest you know that toxicity is low. And Daconil has lower toxicity than does Rotenone which is approved by every organic certifying agency I know of.

My concern has always been toxicity to humans, pets, the birds and bees and fish and all things in nature rather than looking at a product as being organic or non-organic.

[Razorback04]

I suggest you access the data for all pesticides, fungicides, etc. at EXTOXNET which is a consortium of Universities, as you'll see, and that's where you'll get unbiased information.

Thanks Carolyn, I'll check that out today. I'm glad I asked this question because I suspect a lot of other people are experiencing the same problems that I am with EB.

But I've personally experienced vastly superior results from religiously using it early on in the season, even moreso than even bothering with it too much at all later in the season. In my case, too many plants to make it practical when they get huge anyway.

Thanks Suze. Please define "religiously". Once a week? More often? Is there a limit to how many times Daconil can be applied? Also, later in the season, are you still getting EB? Is the onset just so late that you still get a crop anyway?

My issues with Early Blight are such that I'm still able to get a decent harvest, but many of my tomatoes are basically defoliated by now.

This year, I have tomatoes planted in 2 locations. Location A is a spot where tomatoes have previously grown, and was also near some potato vines. The tomato plants were purchased from a local garden center and were set out and mulched a week or so later. The Early Blight showed up quickly and prompted me to try the Daconil a few times. As the tomatoes got larger, I discontinued the Daconil and watched as the plants progressively turned brown and defoliated. In location B, tomatoes had not been grown there for several years and my plants were grown from seed by me. Those plants showed no signs of disease for a long time, but now it's obvious that they're diseased also. The delayed onset of the EB will allow me to get a fairly normal harvest from these plants, but I feel like this soil is now also contaminated and I have concerns about planting here again next year.

Even though I was very careful not to contaminate the plants in location B with anything from the diseased location A, I still ended up with Early Blight in what should have been disease free soil. My question is, what went wrong? Is EB simply floating around in the air?

BTW, virtually every tomato grower that I've spoken with has told me that this has been an exceptionally bad year for "firing up".

[carolyn137]

Is EB simply floating around in the air?

****

Absolutely.

All NEW foliage infections are acquired via airborne means.

And as you've found out if tomato plants with diseased foliage are grown in one area the bacteria and spores can be shed to the soil and then in a subsequent year there can be splashback infection.

I think the instructions on the Daconil label say something like every 7-10 days although I may not be remembering correctly. I think every 5-7 days is best and of course if there are heavy rains you need to reapply it.

Ortho now makes Daconil with a spreader sticker which can help but if your local source doesn't have it you can buy spreader sticker separately and add it.

[Razorback04]

All NEW foliage infections are acquired via airborne means

So, Early Blight is not carried by infected seeds? Are you saying that if I were to save the seeds from some of my Black Krims, they would be no more likely to get Early Blight than those ordered from a reputable seed supplier?

Would you care to take a guess at the % of plants infected via splash back vs the % infected via airborne? I know the mulch is very helpful in a lot of ways, but I'm wondering how much benefit it actually provides when it comes to EB prevention.

Also, I have some Coco-wet. The Spray N Grow folks recommend it as a spreader/sticker for their products. It sounds as if it would work the Daconil. Would you agree?

Lastly, your book came in the mail today........I'm ready to get started on it right away.

[feldon30]

Originally Posted by Razorback04

As for the Daconil, I sprayed it only twice and that was after I had first noticed some spots on the leaves. It seemed to briefly slow down the EB, but only barely. Why only twice? After a few web searches about Daconil turned up some scary info, I decided that it sounded more dangerous than the EB.

Yes, there is a lot of FUD (Fear, Uncertainty, and Doubt) spread about Daconil by people who know very little about it. I have done the comparisons and read the Material Safety Data Sheet (MSDS) of both it and the commonly suggested Certified Organic alternative -- Serenade.

They both have similar health and toxicity warnings. Any of the reports I have seen about negative health effects like rashes and breathing problems with Daconil were in concentrations of 50-75%. In a home garden when spraying tomato plants, the correct dosage is .116%. Yes, that's less than two tenths of one percent.

My Daconil vs. Serenade posting including tables and the side-by-side comparison of the health warnings of both products.

Originally Posted by Razorback04

I've since discovered that it's really, really hard to get good unbiased info on things like pesticides and fungicides.

What's the most important when reading those reports is the dosage and comparing them to the organic equivalents. People are convinced that "organic" is automatically safe.

Capsaicin (the raw irritant/spice in hot peppers) is organic, but too much of it would kill you. Aspirin is acetylsalicylic acid which is a naturally occuring substance found in plants. Too much of it will also kill you. My advice is to be informed and compare the labels and keep dosage and exposure in mind.

Originally Posted by Razorback04

Even my tomatoes that were grown in ground that had not grown tomatoes for several years, eventually developed EB.

EB is an airborne fungal spore which is disturbed and scattered by rainfall and wind. So are anthracnose, septoria leaf spot, etc. Anthracnose is a threat to growers of strawberries, melons, tomatoes, peppers, etc. as it causes soft, rotting sunken spots on fruit.

Mulch has a great effect on reducing "soil splashback" of the infected soil up onto the leaves of the plants. But mulch alone is insufficient for Gulf of Mexico states like Arkansas, Mississippi, Texas, Louisiana, Florida, etc. Not when we have days of nonstop torrential rain.

Daconil is like a prophylactic for the plant, sealing the leaves so that fungal spores cannot bond with the leaves.

I do not want to tell anyone how to garden. The best thing is to make an informed decision and don't let biased websites scare you.

Originally Posted by Razorback04

Ahh, the watermelons. I have a few black spots on some of the crown leaves, but nothing that seems to have affected the vines in a major way. They are now on the verge of harvest, and the biggest problem that I have with them is the fact that we're now in a dry spell. Hopefully, that'll mean even sweeter than normal melons.

I'll try and post some pics in a day or 2..........Both of the EB and the melons.

Looking forward to the pictures.

[feldon30]

Originally Posted by Razorback04

Also, I have some Coco-wet. The Spray N Grow folks recommend it as a spreader/sticker for their products. It sounds as if it would work the Daconil. Would you agree?

Daconil concentrate (29%) comes with an excellent sticker/spreader. It is not only not necessary, but it is not recommended to mix or dilute Daconil with anything other than the prescribed amount of water. The "ready to use" bottles of Daconil are a low quality product and are not recommended. Daconil should be used within 24 hours of being mixed.

[carolyn137]

So, Early Blight is not carried by infected seeds? Are you saying that if I were to save the seeds from some of my Black Krims, they would be no more likely to get Early Blight than those ordered from a reputable seed supplier?

*****

Yes, EB can be seedborne but that's rarely the way in which infections start b'c seed is usually fermented which lowers the amount of any pathogens attached to the seed coat and since infection is quantitative, one rarely gets infection with foliage pathogens that way.

As long as you ferment your Black Krim seeds you should be fine.

I don't know of any commercial seed source that does not ferment or otherwise treat their seeds.


(Would you care to take a guess at the % of plants infected via splash back vs the % infected via airborne? I know the mulch is very helpful in a lot of ways, but I'm wondering how much benefit it actually provides when it comes to EB prevention.)

No way to estimate that b'c the amount of any foliage pathogen that's airborne at any one time is totally unknown.

Mulch can help with splashback infection by preventing soil borne spores and bacteria that were previously shed by infected plants from being splashed back up onto the plant during rain or deliberate watering.

[BR]

Carolyn,

I'm not saying you are wrong about there not being any EB tolerant tomatoes but in my garden Opalka has all but thumbed it's nose at EB while ALL other varieties have had some problems due to wet weather. How can this be explained? Conditions are identical for all varieties.

[feldon30]

There are some varieties that have some natural tolerance to it better than others. In some gardens, Cherokee Purple is the last to get EB. In my garden, Ark. Traveler didn't get it until late. In both years I've grown it, Sungold has been the first to succumb. Some have argued that Potato Leaved tomato varieties have thicker leaves and thus are proof against EB for a bit longer than Regular Leaf varieties. Some people have even switched to PL varieties just to stretch out their season.

I am assuming you are having EB despite weekly spraying with a fungal control and good watering and mulching practices?

Unfortunately nobody has ponied up the money to do scientifically significant EB tests on different varieties especially heirloom/O.P. varieties that have no financial backer. So reports of one variety being better than another are mostly apocryphal.

[Razorback04]

apocryphal??

Good grief, Feldon. I was forced to whip out my dictionary just to read your post. Here's what I found:

1 : of doubtful authenticity : SPURIOUS

Maybe anecdotal is a better word?

2 : based on or consisting of reports or observations of usually unscientific observers.



Seriously, thanks to everybody for all your help. Next year, I will be more prepared to deal with this evil that is Early Blight. My plans currently include good mulching and a weekly Daconil spray regimen. Should I worry about disinfecting the cages or is simply cleaning out the foliage enough?

FWIW, my Arkansas Travelers showed no resistance/tolerance whatsoever towards EB, and succumbed just as quickly as everything else. Of course, that's purely anecdotal. My potato leaved, German Johnsons are holding up pretty well however, so there may be some truth to the idea that PL plants are slightly more tolerant of EB than RL plants.