Help with tomatoes in Cambodia for orphanage

[andyhitomi]

I need help with a hydroponics project just getting started to grow food for a orphanage in Cambodia. I would like to correspond with anyone doing hydroponics in Cambodia, Thailand, Vietnam, or Laos to share information about supplies, bugs, etc. You can contact me using the contact form on my website: Photosensibility | Andy Gray | Cambodia – Japan Photo, Video, Blog .

The initial hydroponics project appeared to start well. We had tomatoes, peppers, and cucumbers all growing well. However, we weren't testing the water at all. The water source is a fish pond, so we probably had issues with that. But, as I said, the plants started out doing well.

After about three months, some very thin white lines appeared on the leaves. Unfortunately, a worker at the orphanage who wanted to be helpful doused them with pesticide. All the plants nearly died from the pesticide. They never fully recovered, and eventually they were pulled out to start over.

The new seedlings were coming up well in starter soil when we noticed very thin white lines (<1mm squiggly lines) on the leaves. It appears the same pest/bacteria/?? has struck them, too.

Any help would be appreciated.

Some basic questions:

1. Is it absolutely necessary to test and control the water? If so, what is the minimum testing we need to do? Do we need to test for biological agents (plant viruses and bacteria)?

2. Do we need to treat water for viruses, bacteria, etc.? If so, we need a very cheap way to do that in Cambodia.

3. As I said above, I would like to be in contact with others in Southeast Asia who can share information about common pests and problems. Any help connecting with others would be appreciated.

Thanks!

[GpsFrontier]

1. Is it absolutely necessary to test and control the water? If so, what is the minimum testing we need to do? Do we need to test for biological agents (plant viruses and bacteria)?

2. Do we need to treat water for viruses, bacteria, etc.? If so, we need a very cheap way to do that in Cambodia.

I'm not in Cambodia, but yes you do need good quality water. Not sure where you can get anything tested there, but I would start by filtering the water with a sediment filter. Then to get rid of any pathogens, bacteria, fungus and any micro organisms, simply boil the water for a minimum of 2-5 minutes, that will kill anything living in the water. Once it cools down to room temp, then I would filter it with a carbon filter, like the ones for making drinking water. Your water should be fine to use then.

[Luches]

Hi andyhitomi,

I am in Northern Thailand and working as a consultant on various projects, at this moment in Sri Lanka and Maldives. I'll keep it briefly here as I prefer contacting you in private eventually. Forums can be a great source of information, but some times a following controversial debate can be confusing and frustrating as well.

Firstly, the bug you deal with is most probably a leaf miner larva called Liriomyza brassicae. Description: Liriomyza brassicae - Serpentine leafminer

And here: bug guide

It's very commonly spread in S.E.A. If it only affects parts of the plants it's often not treated with insecticides. You can clip or cut off affected leafs or only parts as soon as you spot them. That is what I often do. Tomato plants do not mind if they get a little pruned in such way. It's only a treat for most plants if largely spread - see Wiki description.

To prevent seedlings to get affected early, which isn't a good thing anyway - as the tiny plants may delay development considerably, - you should cover them with a so called Aphid-net, that prevents miner flies to lay there eggs on them in the first place. That is what we use in Thailand for seedlings and with hydroponics.

The problem is not "water born", and as long as your plants grow well with the combination of the pond water and your nutrients, - I wouldn't be concerned (or not give priority) to this part.

Again, I am glad to help out and get in touch with you personally. You can always contact me by P.M. at this place from your side. But (and this doesn't actually concern you at all andyhitomi) just saying that I will not engage in any futile debate here anymore that may follow my explanations and advices by certain members who seem to have a strong urge for controversial debates.

This actually happened systematically in the past, and hence I will not reply to any "invitation" of that kind. I am in no mood for that and nor have I got the time.

[andyhitomi]

Luches, I was hoping you would respond, since I saw in another thread that you are in Thailand. I will PM you, but I'll also reply here.

We thought it might be leaf miners, but we were surprised they attacked the seedlings so quickly. That's why we wondered if something was in the soil. If we can solve the immediate problem with Aphid nets, that will help greatly.

As for boiling and filtering the water, that's not feasible in Cambodia -- certainly not at the economic level we're aiming for. Even filtering is a tall order.

We are concerned about testing the water, mainly because the cost of "surprises" (e.g., starting over") could be so high. We're thinking the levels of ammonia in the fish pond could be reduced by aerating it, but we don't know anything about the pH, etc.

Anyway, these details could stretch out. I'll PM you from here. Thanks.

If anyone else is working on hydroponics in SE Asia, please let me know. I'd love to have more people to converse with about these things.

[Luches]

I'll reply here because it might still be of common interest.

I understand your reflection about soil/water related causes with the infected seedlings. But miner flies even prefer "tender" seedlings, - and if they detect them they lay eggs on them at a very early stage. It happened more than once to me too.

I am quite aware of the situation you have to face in Cambodia. I know of people who used to work with some projects over there who couldn't believe how developed and advanced Thailand is compared to Cambodia, when they came over - Cambodia is real third world in many senses of the term right?

PH is indeed a matter of concern, but from a purely pragmatical point of view, remember that you were growing successfully. That indicates that the PH can't be that bad - although it is prone to change with seasons (monsoon- versus dry season). But I can probably help you out with this matter on a private/donation way. Until then, if you get to test it - around (close to) 6 is all you need. As for the ammonia content, I believe that plants can tolerate higher levels as the fish. To solve eventual high ammonia levels, best is to promote bacterial activity that will break it down to Nitrates and eventually to absorbable Nitrogen. A secondary pond with "nitrate-hungry" water plants may also be an option. But then again your hydroponical plants can make good use of that nitrogen and hence it mainly and actually turns around promoting bacterial activity. I'd recommend to investigate in aquaponics as well, - but here again there is a learning curve and time to take.

Yeah, as you said... all this can be stretched out indefinately

PS: earlier I didn't mean to "discourage" anyone from any input, I was only saying that there is no way, I'll engage in any kind of futile debates like in the "past"...

[andyhitomi]

My friend who is managing the project has plenty of mosquito nets available. Would a mosquito net suffice as an aphid-net? I was just checking, and it seems that aphid nets are specially designed to allow UV rays to reach the plants, and I also wonder if a mosquito net would have small enough openings... If we need an anti-aphid net, then we'll have to search for a supplier in Phnom Penh.

[Luches]

Hi again,

Originally Posted by andyhitomi

I was just checking, and it seems that aphid nets are specially designed to allow UV rays to reach the plants, and I also wonder if a mosquito net would have small enough openings... If we need an anti-aphid net, then we'll have to search for a supplier in Phnom Penh.

I was thinking of it too... obvious, isn't it...
When comparing the mesh size of both (mosquito nets we have around here), it seems they are similar. The aphid nets exist in 2-3 mesh sizes I think, - the finer the safer. But the downside of the fine-meshed net is that it does let less wind or airflow through, which is important with net-houses. I guess the white color is letting the UV through anyways. You may improvise a box-shaped frame first (bamboo or PVC tubes etc), put it over the seedlings and than cover it with the net.

It's worth a try with the mosquito net, you can't do much wrong. Too silly you are a bit far away, because I just bought a roll of 100 meter...