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Downy mildew?
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Author:  concealed [ Feb 25th, '11, 13:21 ]
Post subject:  Downy mildew?
Having a hard time with this one as it could be a few different things. This is my indoor aquaponics and our indoor temp has been low but the water is heated so the humitity on the plants has been high. It's more mild weather now. Last night I foliar fed the leafs Maxicrop + Iron and got them nice and wet, today the mildew-type problem really took off. I'm going to put a fan on them and see if that clears it up a little.

Sorry for the florescent effected cell phone pics, I can email full-resolution if you want to see a copy.

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Author:  concealed [ Feb 25th, '11, 13:22 ]
Post subject:  Re: Downy mildew?
the dieing basil

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Author:  earthbound [ Feb 25th, '11, 15:43 ]
Post subject:  Re: Downy mildew?
Ummm, where's the choice for none of the above? I think you'll find that it's thrip.

You should be able to see some examples on this page, http://www.google.com.au/images?um=1&hl ... =&aql=&oq=
Author:  faye [ Feb 25th, '11, 15:47 ]
Post subject:  Re: Downy mildew?
Check for minute caterpillars under the leaves and droppings as well.
Author:  scotty435 [ Feb 25th, '11, 16:19 ]
Post subject:  Re: Downy mildew?
Amoung the different plants I think you have more than one thing happening. The only one that looks familiar to me is the dieing basil pic - looks like this could be spider mites from the damage. Look on the underside of the leaves with a magnifying glass for most of these - they usually produce webbing which you might notice as well. I wouldn't rule out anything else but I think it's worth a check.
Author:  netab32 [ Feb 25th, '11, 19:48 ]
Post subject:  Re: Downy mildew?
Hi Concealed,

Hubby had a look and reckons it looks like powdery mildew damage - different to downy. He reckons it would have showed more of a yellowish disfiguration if it was downy, also it doesnt usually show in a quick growing crop as it takes a while to take hold before showing damage.

Might need to know some more info to diagnose better, like what it was looking like 2 weeks ago. Try spraying with milk (think thats what you use???) as sulphur is the usual treatment but not sure if it can be used in AP.

He was wondering whether you might have had a fruit bowl near the system that has had fruit thats gone a bit mouldy? Could be the contaminant.
Author:  concealed [ Feb 26th, '11, 01:27 ]
Post subject:  Re: Downy mildew?
First, thank yall for the great replies.

earthbound wrote:
? I think you'll find that it's thrip.

+1. I brought in some mint a while ago and it got infested with little white bugs. I threw the mint out and there is an occasional white bug on the rest of the plants (about the size of a pen-head each)

faye wrote:
Check for minute caterpillars under the leaves and droppings as well.

When I pulled my onion out of the hydroton, it has little white worms on it. Maybe 1 or 2 cm each. I put the onion in the fish tank and watched bugs fall off hoping the fish would eat them, no takers.

scotty435 wrote:
Amoung the different plants I think you have more than one thing happening. The only one that looks familiar to me is the dieing basil pic - looks like this could be spider mites from the damage. Look on the underside of the leaves with a magnifying glass for most of these - they usually produce webbing which you might notice as well. I wouldn't rule out anything else but I think it's worth a check.

Good idea - I'll look in to it. I should have posted a pic of the kale, it has a different condition as the end of one new leaf is wilting off. Could it be I put the 4-lamp T5 too close? it is pretty warm under the lights.

netab32 wrote:
Hi Concealed,

Hubby had a look and reckons it looks like powdery mildew damage - different to downy. He reckons it would have showed more of a yellowish disfiguration if it was downy, also it doesnt usually show in a quick growing crop as it takes a while to take hold before showing damage.

Might need to know some more info to diagnose better, like what it was looking like 2 weeks ago. Try spraying with milk (think thats what you use???) as sulphur is the usual treatment but not sure if it can be used in AP.

He was wondering whether you might have had a fruit bowl near the system that has had fruit thats gone a bit mouldy? Could be the contaminant.


I didn't think it was powdery because I didn't see anything on the leafs per say. However, we have had some fruit/veggies rot in our kitchen nearby recently. I'll try some milk when I get some next week, thanks!
Author:  scotty435 [ Feb 26th, '11, 03:22 ]
Post subject:  Re: Downy mildew?
I see lots of little black spots in the photos you provided - are these
1. droppings - caterpillars and other insects
2. mold spores
3. mites

A magnifying glass should let you tell the difference - the mites will move, mold spores vary in shape but are often spherical. You might also take a look at those little white bugs. While I think Joel is right about them being thrips, it could also be that they are springtails which feed mainly on detritis but some can cause problems with seedlings. Thrips will mostly be on the underside of the leaves. Springtails launch themselves in the air with their tail when threatened and you will probably see them on the media as much as the plants.

Thats what I would check. Regarding the kale - yes the heat from the lamp could cause wilting but it would have to be very close.
Author:  concealed [ Feb 26th, '11, 03:46 ]
Post subject:  Re: Downy mildew?
Most of the black spots popped up overnight when I sprayed the leaves with Maxicrop + Iron. I realized that I dosed it much higher than recommended too. I tend to not measure and just poor it in :P. I'll provide more analysis tonight when I can look at everything through a magnifier.
Author:  concealed [ Mar 13th, '11, 03:04 ]
Post subject:  Re: Downy mildew?
earthbound wrote:
Ummm, where's the choice for none of the above? I think you'll find that it's thrip.


It's definitely thrip. Any good ideas on control? This is a very small indoor system so releasing helpful bugs is probably not an option.
Author:  earthbound [ Mar 13th, '11, 15:23 ]
Post subject:  Re: Downy mildew?
We have had issues controlling thrip around here so generally we follow a number of steps... When you see a plat with thrip, pull it out and dispose of it immediately. Don't plant susceptible plants back into beds where there have been thrip recently. try and increase general plant health to help fight off pests, like increasing feed/nutrient available, using seasol.

Nowadays we still get them a bit, but like I say, we just whip plants out as soon as you see it and it seems to keep them at bay most of the time.
Author:  ivansng [ Mar 13th, '11, 17:02 ]
Post subject:  Re: Downy mildew?
concealed wrote:
Most of the black spots popped up overnight when I sprayed the leaves with Maxicrop + Iron. I realized that I dosed it much higher than recommended too. I tend to not measure and just poor it in :P. I'll provide more analysis tonight when I can look at everything through a magnifier.


Hmm... Are you suggesting that you mixed the maxicrop and iron in the same spray container and sprayed the leaves??

If so, I think you will find that the iron will cause the leaves to die... There is a thread somewhere of someone who did this and share their findings...

So, spray Maxicrop and add iron to the drain or growbed inlet...
Author:  concealed [ Mar 13th, '11, 21:04 ]
Post subject:  Re: Downy mildew?
EarthBound: Thanks. This is a small system and I was able to run an oscillating fan that covered all of the plants. It seems like fan slowed down their progression but obviously it can't eradicate them. Damage continues like normal when I stop running the fan so often.

ivansng: The actual product is maxicrop w/ iron. It's added to the solution by the manufacture. They have foliar feeding instructions on the bottle, but I don't measure, I just pour :P
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