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Old November 26, 2009   #1
bionicman
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Default Tomato plants curling downwards, wilting from the bottom up

I am having a very odd problem with my cherry tomato plants. I am growing using aeroponics (low pressure). The plants are wilting from the bottom branches upwards. As each branch wilts and dies the next one up does the same. The leaves are also curling downards and curling in on themselves. The bottom most leaves are tough and leathery and have purple and yellow color. The main stem is purple near the bottom. The person at the hydroponics shop said that he believes my nutrient tank is getting too cold. I checked the temperature and its 70F during the day. I know the air temperature under the 400W HPS lamp remains around 74F during the day, but goes to about 64F at night. Lowest nightime air temperature in the last 30 days was 61F. I am uncertain what the temperature of the water (nutrients) goes down to at night time. I am growing these in my basement and the nutrient tank is sitting on the cold concrete floor of my basement. I have tried two different fertilizers and have grown the same tomatoes in deep water culture without issue using the same fertilizer. I have tried adding hydrogen perioxide to the nutrient water but it did not help. The roots are white and look healthly although the number of roots seems to be stunted as I would expect more roots after 30 days of growing than I am seeing. I have tried regrowing the same tomato plants several times and each time I have cleaned my system out completely, yet I still end up with the same issue. The only thing I can think of us that the water is getting too cold at night. I have my aeroponic sprayers running 1 minute on and 5 minutes off, 24/7. My 400W HPS lamp runs 16 hours on, 8 hours off each day. Running about 700PPM right now, ph is around 6.3. I have tried higher and lower nutrient levels and higher and lower ph levels which did not appear to help.

If someone can help I would appreciate it. I will post pictures in a moment.

Last edited by bionicman; November 26, 2009 at 02:30 PM.
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Old November 26, 2009   #2
bionicman
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Here are the pictures.

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Old November 26, 2009   #3
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bman, everything points to a Phosphorous deficiency but can't be sure. Would definitely get 2 inch thick slab of styrofoam like they use to insulate houses with and set your nutrient tank on that. Then I would get a aquarium heater to match the capacity of your nutrient tank and run it at 25C/77F 24/7. With nutrient heating your plants won't be affected as much by ambient air temperature fluctuations. Ami
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Old November 27, 2009   #4
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Thank you for the response. I monitored the water temperature all night and it did not go below 68F. The air temperature went as low as 66F over night. So you think the water temperature is preventing nutrient uptake? I checked the nutrient temperature of my deep water culture system where I have also been growing this variety of tomatoes and its the same temperature. Perhaps the act of spraying the roots makes it more difficult to absorb the nutrients?
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Old November 27, 2009   #5
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bman, actually nutrient uptake of NPK is highest at 20 deg C. Plant growth is highest when the solution temperature is between 25 and 30 deg C. 25 deg Celsius seems to be the happy medium between the two. As the temperature of the solution drops below 68 deg F. Phosphorous uptake drops at a higher rate than does Nitrogen and Potassium. Have you considered putting mycorrhizae in your solution? This is just one of several formulations on the market today and this one is from fungi.com. And one application should be all that is needed to innoculate the roots. Ami

MycoGrow™ Hydro
MycoGrow™ Hydro consists of a concentrated blend of spores of 4 endomycorrhizal fungi species. With a particle size of less than 220 microns (#70 screen), this powder is ideal for "water in" or "spray" applications. Mix 1.5 tablespoons or more per gallon of water or compost tea.
One ounce HMHP1O $4.95
One pound HMHP1P $59.95
Note: this product cannot be shipped to Hawaii.

Contains concentrated spore mass of the following:
Endomycorrhizal fungi Glomus intraradices, Glomus mosseae, Glomus aggregatum, Glomus etunicatum
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Old November 27, 2009   #6
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Okay, thanks for the reply. I have put the nutrient tank on a piece of insulation. The dry fertilizer I use has a NPK ratio of 7-11-27 and I add calcium nitrate to this. I wonder if this just isnt a great formula for tomatoes? I have some dutch nutrient two part liquid nutrients I could also try. I will try to raise the nutrient temperature.
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Old November 29, 2009   #7
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What kind of trace elements in the 7-11-27? (It should be
fine for tomatoes as long as it is not oversupplied. The ratio
is ok.) A lot of growers, especially container growers, use
kelp, Planters II, Fertall chelated minerals, and similar to
supply minerals that are not in their main N-P-K source.

A document with symptoms of mineral deficiencies on
tomato plants:
http://4e.plantphys.net/article.php?ch=5&id=289

A document from TotalGro that discusses interactions between
nutrients in the case of oversupply of some nutrient:
http://www.totalgro.com/concepts.htm
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Old November 29, 2009   #8
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bman, from what I've seen from nutrient formulations, 4-18-38 for tomatoes and 10--8-32 as an all-around. Came across some interesting info from our cannabis grower friends on aeroponic growing. You have seen the nutrient availability charts at given ph ranges, well there are two charts. One for growing in "Mineral Soils" and the other for "Soiless Mix". And the main difference is the uptake of Phosphorous and Manganese. The thread also has excellent information on micro and macro nutrients and how the plant uses them plus other info on aeroponics.
bman, I think ph could be another part of the puzzle concerning your problem. Dropping it to 5.8 temporarily might tell us if we are on the right track. Here's the link to the thread I was referring to. Ami

http://www.icmag.com/ic/showthread.php?t=52431
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Old November 29, 2009   #9
bionicman
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Wow, that is really interesting about the ph. Great research!. My ph probably drifts from 6.2 - 6.5 on average and I always thought that was fine but perhaps that's the source of my nutrient deficiency. I just dropped the ph down to 5.7 and will aggressively monitor it. From looking at that chart it does appear that phosphorous is not well absorbed at a ph of say 6.3 and there is a big difference between 6.3 and 5.7. I might even try 5.5 but for now I will start at 5.7.

The nutrients I am using are a 7-11-27 and I add calcium nitrate at about half the rate of the hydroponic nutrient. So if I add say 5ml of the hydroponic nutrient I will add 2.5 ml of the calcium nitrate. The hydroponics guy at the store said "that should be about right" but I guess it depends on what you are growing. Calcium doesnt appear to be my issue at the moment.

Contentration of hydroponic nutrients:

Total Nitrogen (N) - 7%
Available Phosphoric Acid - 11%
Soluble Potash - 27%
Magnesium - 3.75%
Sulphur - 4.8%
Iron - 0.1%
Manganese - 0.085%
Zinc - 0.03%
Boron - 0.0273%
Copper - 0.0041%
Molybdenum - 0.009%
Chelated metal complex of diethylene triamine pentaacetate DTPA minimum content - 0.7%
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Old November 29, 2009   #10
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Calcium is quite important to a tomato plant, but one does not
really see much in the way of deficiency symptoms until fruit
start to develop (blossom end rot). Looking at your formulation
at the bottom, I might want a little more iron, but the leaves
are not showing iron deficiency symptoms, so I guess it is ok
in the context of the levels of the other nutrients there.
(I have seen obvious iron deficiency symptoms on plants
growing in soils with more iron than what your fertilizer
supplies but a lot higher zinc levels, too.)

Some kind of mineral salt not in any of the ingredient lists
that builds up in the solution, maybe?

The page below indexes documentation on a lot of different
kinds of "plant stress", including mineral toxicities, toxic
salt buildup, etc:

http://www.plantstress.com/Articles/index.asp
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