You are sure you have pith necrosis? This appears more like an epidermal necrosis. Pith necrosis often isn't visible from the outside of the stem and only shows on a cross-section as it is the actual pith, the stem core, that is affected?

In some really severe cases some small epidermal signs could be seen but I would expected the entire plant to have collapsed if it was that severe.

This stem has more of a Late Blight appearance IMO. Are you located in one of the locations where LB has been really active this year? Were the fruit affected? If so how severely? Pith necrosis effect on the fruit is pronounce. LB effect much less so.

Dave

Thanks Dave,
I can find nothing at all on epidermal necrosis. Can you please give me a link. Regarding it possibly being Late Blight the fruit has not been affected at all. I have noticed that when I remove the affected stems they are completely hallow inside. I have been battling this problem for about a month now..The plant that I showed in the pic is now the worst of the 3 plants that I'm having issues with. The brown streak is widening and soon the whole stem will turn brown and die and when I remove it, the stem will be hallow. I'm thinking of removing the large green fruit still on the vine and then pulling the entire plant. The Pearls of Wisdom which is right next to it has no symptoms of brown streaks on the stems yet. Yes this is 2014 growing season and it has its own issues. I germinated the seeds. Planted healthy plants in ground on May 12th and then subjected them to the elements. I wish I had some idea as to what the problem is so I can try and prevent it from happening next year. Learning experiences are great if you can learn. Oh well. Any thoughts you can give me are appreciated. You are the backbone of Gardenweb. Thanks again

I have noticed that when I remove the affected stems they are completely hallow inside. I have been battling this problem for about a month now..
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Most probably not a Late Blight. If I am not mistaken LB will finish the plant in less than a week.

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This post was edited by seysonn on Wed, Aug 13, 14 at 5:16

Thanks sey...I'm not familiar with LB but after googling it I saw how the fruit was affected and mine are ok...also have you ever heard of epidermal necrosis. I can't find anything info on it. Any info you can provide would be appreciated.

It would help to see the overall plant, leaves probems, and to see whether the brown line traveled up from the soil. Pictures like this out of context don't unsually have enough information. You didn't tell Dave where you are growing. These details are important if you want to put your problem in the appropriate context.

I bet it is Fusarium, if the brown line started at ground level.

^I had an issue with fusarium crown rot on one of my tomato plants earlier in the season, but it was contained to much lower on the stem...didn't get higher than a few inches from the base and went around the entire stem, which caused the plant to topple over. It did look like the brown dead material in the OP's picture.

Sorry Joe, didn't mean to add to the confusion. Epidermal necrosis isn't a disease per se. It is just a label for describing the location of the necrosis and is a symptom that can be associated with many causes. Simply refers to necrotic lesions visible on the epidermal layer of the stem, the 'skin' layer, as opposed to the pith or the cambium or the xylem, etc.It is associated with Late Blight, Early Blight, Alternaria Canker, injury, and several of the bacterial diseases.

If the fruit off that particular branch were unaffected then no it likely isn't pith necrosis nor Late Blight. But it also probably isn't Alternaria or any of the various bacterial diseases either as all affect the fruit as well.

That leaves Timber Rot as a possibility as well as Fusarium but again the symptoms are not classic for either. And the various root rots like phytophthora etc. that can only be diagnosed by pulling the plant.

So bottom line without cultures and microscopic examination you may never know what it is beyond a doubt. The only comfort comes from the fact that if you choose to not pull it and if the plant survives the treatment for all of them is the same - remove affected foliage, spray with fungicides, and monitor it.

Dave

Hi Joe, I had one plant succumb to exactly what you are describing. The leaves on mine were also affected with septoria. The stems were hollow as well and I finally cut it down. The fruits never had a chance to ripen. One other tomato, Azoychka, is having similar issues but has managed to hang in. The rest of my plants seem to be ok.. It's been a weird season.
Sharon

Thanks to all who responded to my plea for help. Yes Dave I agree with you and your statement, "without cultures and microscopic examination you may never know without a doubt". I'm organic so I rely on Serenade, and powdered milk foliar, etc spraying. Do they work? Honestly that's a very good question. My approach now is to remove the affected leaves, branches. I will spray and hope that it delays the spread of the pathogen. In the case of the plant whose picture I posted, I did remove that entire stem. The other stem is ok and has large fruit on it which have not been affected to date. I'll continue to monitor it closely and hope that the fruit begins to ripen so I can remove it immediately. In the future I'll take the "Alfred E Neumann" approach and that is "What Me Worry". I grow my tomatoes from seed. When I put them in ground they are healthy. After that "Mother Nature" takes over. Yes, you can water and feed them and that's about it. What else can you do? Well there is always next year! If at first you don't succeed try try again! Happy gardening everyone!

Joe - when you pull the plants examine the roots and look for the symptoms of RKN (root knot nematodes) or phytophthora.

Dave

Ok Dave will do. Thanks...Question for you...if this is a soil borne pathogen how is it that the plant which has been in the soil since May 12 is just now being affected. Are all pathogens present in the soil and only affect the plant when stress lowers its ability to battle the pathogen and thus it succumbs to the disease?