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Papaya plant root rot

Discussion in 'Plants' started by srujan, Apr 29, 2016.

  1. srujan

    srujan New Member

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    Hi all,

    I am new to aquaponics and this forum. I have build my system using CHOP2 principle. Currently i am running a fishless cycle from last 3 weeks with some tomotoes, colour bell peppers, egg plants, banana & papaya. All these were planted 10 days back. All plants seemed perfect untill two days back, from last two days some plants started withering and today we observed that papaya plant roots are rotted. This system is of 20000 litres fish tank capacity and there is no oxygenation input setup.
    Attached the pictures of withered bell peppers and papaya rotted roots. uploadfromtaptalk1461929967726.jpg uploadfromtaptalk1461929988042.jpg uploadfromtaptalk1461930002848.jpg uploadfromtaptalk1461930035966.jpg uploadfromtaptalk1461930059577.jpg

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  2. srujan

    srujan New Member

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    Just to update...so far tomatoes and banana tress are doing fine

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  3. Yabbies4me

    Yabbies4me Administrator Staff Member

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    Hi Srujan,

    - What is the operating method for this system?... ie: Siphoned Flood & Drain, Timed F&D, or Constant Flood.
    - What is the max water temp during the middle of the day?
    - What are the air temps during the middle of the day?
    - How far under the surface of the gravel is the maximum water level when the grow bed is at the top of a flood cycle?
    - Is there any aeration in the system at all?... ie in the fish tank or sump tank.
    - What is the water pH?

    On another note unrelated to the above issues, it's not recommended that fruiting plants be planted in new systems, they generally don't do that well and they nearly always develop nutrient deficiencies very quickly. Ideally you would grow only leafy greens, such as Lettuce, Bok-choy and similar Asian greens, herbs etc, for about the first 4-6 months, until the system has built up a sufficient nutrient bank.
    .
     
  4. srujan

    srujan New Member

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    Hi Yabbies,

    This system is a timed Flood & Drain. Flood time is about 15 mins and 45 mins drain cycle.

    Didnt measured my water temperature gusseing it may be around 32 to 34°c during middle of the day. It is Mid summer over here with temperature being around 43°c. All my fish tanks & sump tank are under 100% shade net, growbeds are under 50% PE shade net.

    The water level is two inches above the gravel when flodded. Since it is mid summer, thought with allowing water to reach above the gravel i can suck all the gravel heat so that heat wont build up and damage the plant.

    There is no extra aeration. Planning to add aeration system once i introduce fish into the system

    Water PH is around 8.2

    And thanks for the heads up with fruit plantaion during the initial months, will try to add leafy greens instead fruit plants.

    Thanks.
    Srujan.

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  5. Murray

    Murray Site Admin Staff Member

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    By flooding 50mm above the top of the gravel you are heating the water more than it should be. Loads of aeration is always good.pH is too high. Why is it that high? Is it the source water or is there limestone in the media?
     
  6. srujan

    srujan New Member

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    Hi Murray,

    Thanks for the update and i am defeanetly planning for the aeration.

    My Problem with PH is the source of water. Initially i thought that problem was with my gravel media as when i tested the water right after they come out of the ground the PH showed 7.4. But i observed that my PH always stays at 8.2, if there is a problem with my media which will increase the PH constantly why would the PH stay at 8.2. So this thought made me to test the water again, i collected some sample ground water and tested the PH, it showed 7.4 and i let the water to settle and waited for 24 hours to test it then the PH showed 8.0.

    I am thinking that from the over flooding or somehow(maybe from the nursery from where i got papaya plant) there might be "phytophthora" fungus got introduced into the system and affecting all the papaya and since pepper plants are vulnerable as well they are also getting affected.

    Is there a way to identify if "phytophthora" is the real issue and treat them without affecting the fish in the future when i introduce them into the system.


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  7. Murray

    Murray Site Admin Staff Member

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    Overflooding will encourage phytophthora. The only way to deal with it is to have fairly short cycle times, that is, flood and drain cycles, keep the bed flood level to at least 50mm below the surface of the gravel and lots of aeration throughout the system. Use of auto syphons in media beds is usually sufficient but a timer system is fine too. That is fast fill and long drain cycle.
    It is not known by itself to affect fish but is sometimes in concert with other fungal type problems.
     
  8. srujan

    srujan New Member

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    Hi Murray,

    I have read that people are doing CF in their growdeds and working out AP successfully.
    I think my problem might be the water level in the growbed.

    I will decrease the water level to 50mm below the gravel and see if i can save my remaining Peppers and Papaya.

    Thanks Murray & Yabbies for your inputs. Never thought that i would get response from such legendry guys. I am your "Ekalavya" student... :)

    I will update how this goes

    Thanks,
    Srujan.

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  9. Yabbies4me

    Yabbies4me Administrator Staff Member

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    Hi Srujan,

    IMO the Constant Flood method is not desirable in very warm climates.

    Once your water temp exceeds 25C it's ability to hold oxygen reduces greatly with every degree of temp rise. In your situation, with 32-34C water temps, the water will be retaining very little oxygen, especially when running CF, and even more so with no supplementary aeration in the FT or ST. Consequently the plant roots will be constantly in a warm, wet, low oxygen environment, a perfect recipe for root rot.

    If you were to run siphoned Flood & Drain with regular F&D cycle times of around 15-20 minutes (determined by the diameter of the standpipe in the siphon) you would be exposing the plant roots to fresh air and oxygen 3 to 4 times an hour. Plus, the water return from an activated siphon back into the FT or ST is much more of a rush of water than is experienced with Timed F&D or CF, so it will add more oxygen to the water.

    Whatever method you decide to run with, I would ensure, as Murray has already pointed out, that you have the max flooded water level about 50mm below the surface of the gravel.
    .
     
  10. srujan

    srujan New Member

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    Hi Yabbies,

    Thanks for the insights.
    I have decreased the standpipe length by 2 inches as suggested so that water level will be 2 inches below the top of the gravel.

    And also i am planning to replace my timer based F&D with a Siphon based one. Earlier i had tried with self made siphons and had no luck. Siphons used to start fine but never stops. I had connected all my four growbeds (11ft × 4ft each) to a 2" pvc drain line and the stand pipe in each bed was 1.25" diameter. I followed affnans principle to design them.
    I am thinking that since all the beds are attached to a single drain line and constanly draining one after the other it might have problems sucking air back to stop the siphons.

    Please let me know if you have any suggestions on stand pipe sizes for such long beds and also drain pipe design into sump tank.

    Thanks,
    Srujan.



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  11. Yabbies4me

    Yabbies4me Administrator Staff Member

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    I'm going to make the assumption your GB's are the widely recommended 30cm (1ft) deep. This would give you a gravel volume of about 1,200L, or a smidge over. In that situation the 32mm (1¼") would be the minimum standpipe diameter you would want.

    With siphon designs, keep them simple (see pic below). They don't require inverted reducers atop the standpipe, nor do they require breather tubes etc. If you adhere to the following design principles they will work well.

    (a). Cut plenty of slots/holes in the outer gravel guard so the water flow isn't restricted. Slots are preferred over holes, especially if using exp' clay growing media.

    (b). Ensure the water inlets into the bell are sufficient so the water flow is unrestricted and can keep up with the amount of flow the 32mm standpipe will allow. Also ensure these slots/holes aren't at the very base of the bell, but up the bell a little so water isn't being drawn from the very base of the GB, and so the siphon cuts off when there is still around 40-50mm of water left in the GB.

    (c). Fit a 90 degree elbow to the standpipe a few inches below the GB, followed by a short run of horizontal pipe of the same diameter. probably about 25-30cm in length for the 32mm diameter pipe you are using.

    (d). The short run of horizontal pipe should then dump into a much larger diameter return line back to the ST or FT, 90mm stormwater pipe is widely used because it cheap. This return line should not be airtight and should have a reasonable downhill angle to it, so it drains freely.

    As far as your problem with the siphons starting but not stopping is concerned, there is usually only two causes for this. The first and most common being that the water flow into the GB is too fast. The second being that your siphon is located in the lowest point of your GB and the water inlets your bell are at the very base of the bell.

    If you keep the following saying in mind it will help you out:

    If the siphon won't go, the flow is too slow.
    If the siphon won't cease, the flow must decrease.

    Cheers!
     

    Attached Files:

  12. srujan

    srujan New Member

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    Thanks Yabbies for sharing the general thumb rules considered while desgning Bell Siphons.
    Seems like as you mentioned in your "C" point my drain line might be the problem. Will try to follow these in my next built.

    One more question is how long the plants survive on the added nutrient, i mean my plants are relying on the Ammonium Sulphate from last three weeks (two table spoons daily for 15000 litres water). Is it bad for them to rely on this type of nitrate source for this long?

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