Ask-a-Dave's-Gardener: Greenhouse Cherry Tomatoes -> fuzz -> yellow -> wilt, 3 by LorenAmelang

LorenAmelang wrote:
Once the weather got seriously hot, and lots of tomatoes ripened, all of the plants, both in the greenhouse and out in the garden, began to wilt from the ground up. Outdoors, watered daily from above by Rain-Birds, the top half of each plant remained relatively normal while the bottom half wilted totally. Now that most fruits are ripe, the tops have wilted as well, the patch looks like late October rather than early August.

In the greenhouse, with drip irrigation at soil level, a few stems still have a bit of green on the very tip, six or eight feet from the soil, but most died completely after ripening fruit. All but one plant sprouted new green leaves from near the soil. These would get maybe three feet tall and some produced fruit, but they also died from the ground up - and were replaced by more new sprouts.

All of the current crop of new sprouts look green and healthy at the moment - but they have not reached the three-foot level where they seem to encounter problems. I'm beginning to think the hollow stems I've noticed when pruning away the dying branches might be the problem. But my symptoms don't exactly match the descriptions I've found:


[HYPERLINK@uconnladybug.wordpress.com]
[My comments in brackets...]
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tomato pith necrosis, caused by the soil-borne bacterium Pseudomonas corrugata.

The earliest symptom is chlorosis or yellowing of the younger leaves. [But mine lose older leaves first...] As the disease progresses, leaves may wilt and become necrotic (dead). Infected stems may or may not have visible dark lesions. [No lesions here.] 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. [That's my symptom...]

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. [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, and with plants starved for nitrogen (new soil brand proved deficient). Problem did become obvious just about when green fruits reached full size.]

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. [Again, my problem appeared worse in nitrogen-starved plants, in pots in a solarium with hot dry days, carefully staked and tied, and watered with drip at the soil level.]

[But the "chambered or hollow pith" has been obvious through the whole adventure!]
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Appears there are many varieties of this problem, but most seems to develop brown pith, spotting, lesions, and sloughing of bark. [Mine had none of these, the stems appear perfectly normal and green from outside, and the pith white, even after all the leaves have wilted.]
[HYPERLINK@www.apsnet.org]


"Pith Autolysis" seems to occur "when the plant cannot meet its carbon needs by photosynthesis alone", leading to hollow stems without other symptoms. [But I do have serious wilt symptoms.]
http://aob.oxfordjournals.org/content/75/6/587.full.pdf


Other descriptions mention finding insects inside the stems - I've never seen any insects or darkened areas or anything but white pith, and have never seen any openings in the stem walls.

(See photos)


Beyond the hollow stems, the most unique symptom I have is tomato fruits with "cantaloupe skin" - a pattern of slightly raised lines on the surface of green or ripe fruits that looks exactly like the skin of a cantaloupe. The pattern is about half the size of the texture of a full grown cantaloupe. It may cover the whole fruit, or just a part of one side, and seems to always touch the stem. Affected fruits seem bland and mealy but have no added taste. In extreme cases the skin gets thick and hard and eventually splits and dries inward.

(Photo shows mild occurrence.)


And one other symptom I've noticed through this whole year, on healthy-looking branches as well as sickly ones in the greenhouse... When I tap the blossom areas to encourage pollination, some of the petals fall off of the flowers. In previous years I could tap or shake much more aggressively without losing any petals.


At this point the question is "What do I need to do to prevent whatever this is from infecting next year's crop?" Since all the plants, indoors and out and many different varieties, ended up unhealthy, and I remember a few samples seemed affected at the 4" pot stage last spring, maybe this began in the first starting flats? No idea what could have been different this year...

This message was edited Aug 3, 2016 2:02 PM