This summer we had an interesting tomato disease in the diagnostic lab. It’s tomato pith necrosis, caused by the soil-borne bacterium Pseudomonas corrugata.
Necrosis and wilt symptoms on tomato plant caused by tomato pith necrosis.
The earliest symptom is chlorosis or yellowing of the younger leaves. As the disease progresses, leaves may wilt and become necrotic (dead). Infected stems may or may not have visible dark lesions. The sample received in the lab this summer didn’t have this symptom. The primary symptom in this case was wilting and necrosis of the upper part of the plant.
To investigate further and to check for wilt diseases of tomato, the lower stem was cut in half longitudinally. The characteristic symptom of tomato pith necrosis, a chambered or hollow pith or center of the stem, was observed. In some cases, this is white as shown in the photo.
White chambered pith in tomato stem.
More advanced bacterial colonization results in the browning and softening of this tissue. The vascular system may also be brown. This tissue is in the outer part of the stem and the sample’s vascular browning is pictured below. Two wilt diseases of tomato caused by fungi, Fusarium wilt and Verticillium wilt, both cause browning in the outer, vascular tissue of the stem, but not in the pith.
Stem section with both vascular and pith browning.
White and brown (decayed) chambered pith.
One symptom that is quite distinctive but that was not readily apparent in this case is the development of many adventitious roots on the outside of the stem near the chambered pith areas. Adventitious roots are roots that develop from above-ground plant parts. Sometimes, the infected tomato plant is able to grow out of this disease.
Conditions that favor tomato pith necrosis include low night temperatures, high nitrogen fertility and high humidity. It often occurs when the fruits are nearing mature green, or just before they begin to redden.
To prevent this disease, do not over-fertilize with nitrogen and space, prune and stake tomato plants to promote good airflow around them, reducing humidity.
JA
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August 11, 2010 at 11:44 pm
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May 15, 2014 at 4:43 am
Thank you so much for this article and particularly that first picture showing the white pith. I have been trying to diagnose this disease for a long time. Two different extension offices could properly diagnose it either, which has been frustrating. Now I can address it. Thanks!!
– John in Atlanta.
May 15, 2014 at 4:54 am
I meant to say , two different extension offices could not properly diagnose. – John.
August 13, 2015 at 2:23 pm
I had this last year in my raised bed and now again this year. Any idea how long it takes for the bacterium to die off? Or does the medium need replacing?
August 13, 2015 at 5:31 pm
Hello CC,
It is best to manage fertilizing better as tomato pith necrosis will occur in over fertilized plants and in a high humidity environment where the tomatoes are growing too fast. Pseudomonas is a naturally occurring in the soil but will only attack a plant under conditions of high humidity, low night temperatures and over fertilized plants. Changing the soil in the beds will not change these conditions.
Regards,
Carol Quish
August 3, 2016 at 9:45 pm
Your stem photos are the closest I’ve found to what I’ve seen in my plants this year, but the descriptions are not a perfect fit:
The earliest symptom is chlorosis or yellowing of the younger leaves.
[But mine lose older leaves first, wilt from the bottom upward…]
adventitious roots on the outside of the stem near the chambered pith areas.
[Zero adventitious roots here.]
Conditions that favor tomato pith necrosis include low night temperatures, high nitrogen fertility and high humidity. It often occurs when the fruits are nearing mature green, or just before they begin to redden.
[My problem was far worse in the greenhouse with warmer nights than outdoors, and with plants starved for nitrogen (new soil brand proved deficient). Problem did become obvious just about when green fruits reached full size.]
My whole long story with photos and more symptoms is posted at:
http://davesgarden.com/community/forums/t/1424806/
I don’t know how much of my problem could be due to the hollow stems, or why my plants would give up their lower leaves first if the problem is the stems. But it does seem like they look happy until they get above three feet tall.
Do you see any clues in the photos on the DavesGarden site?
Loren
Your stem photos are the closest I’ve found to what I’ve seen in my plants this year, but the descriptions are not a perfect fit:
The earliest symptom is chlorosis or yellowing of the younger leaves.
[But mine lose older leaves first, wilt from the bottom upward…]
adventitious roots on the outside of the stem near the chambered pith areas.
[Zero adventitious roots here.]
Conditions that favor tomato pith necrosis include low night temperatures, high nitrogen fertility and high humidity. It often occurs when the fruits are nearing mature green, or just before they begin to redden.
[My problem was far worse in the greenhouse with warmer nights than outdoors, and with plants starved for nitrogen (new soil brand proved deficient). Problem did become obvious just about when green fruits reached full size.]
My whole long story with photos and more symptoms is posted at:
http://davesgarden.com/community/forums/t/1424806/
I don’t know how much of my problem could be due to the hollow stems, or why my plants would give up their lower leaves first if the problem is the stems. But it does seem like they look happy until they get above three feet tall.
Do you see any clues in the photos on the DavesGarden site?
Loren
(This is try 2 to post, Firefox said “Comment could not be posted”. Trying Chrome…)