Ongoing Plant Problem

[plantproblem]

Hey everybody,

I'm here looking for some help about an ongoing issue I've had effect 3 of my plants now on a regular basis.

They develop rust/dark coloured spots on lower leaves and slowly fade to yellow starting at the tips. It also has ended up with some dried up tips of leaves that I ended up cutting off. I originally thought this was a calmag issue but I've been supplementing 6ml of calmag per gallon of RO water which to my understanding is more then adequate, this failed to allevate the symptoms.

I then thought perhaps it was a potassium excess because I had given my plants 1/2 ml - 1ml tiger bloom from the fox farm trio, but I've stopped giving that and the problem continues. I'm really at a loss as to what is causing this problem. Any help is really appreciated.

I'm considering increasing the ph of my next watering to 6.2 to help the absorption of calicium.

Please see the pictures for clearly idea.

Grow Details: They have been fed no higher then 600 ppm feedings. PH of water has been kept inbetween 5.8 and 6.0. The nutrients have been calmag, bio root, fox farm trio and molasses in small amounts 1ml per gallon. The plants are in 5 gallon pots with pro mix hp with approximately 15% extra perlite mixed in. Runoff of the plants ph has been between 6.0-6.2. They are being grown in a 4x4x6 tent with a 1000 watt bulb with 440 CFM and carbon filter. temperatures vary between 70F lights off and 84F lights on. The light is approximately 24 inches away from the plants.

Any information I've missed or you need please don't hesistate to ask.

Please help me fix my plants
Thanks in advance,

Plantproblem

 

[GRAPEGODaero]

5.8 ph is hydro. Test the run off water to get your ph without a soil probe. Im thinking u should use 7 ph with soil.

 

[MidwestToker]

6 ml of cal-mag seems a little high. I know they recommend 5 ml a gal, but I've never had to use over 2.5 ml with my RO water. That gets my water to around 150 ppm.
Pro=mix HP is soilless so 5.8-6.2 should be what you're shooting for, also the pro=mix should of been limed already.

 

[plantproblem]

ya the promix did come limed. I'm at a loss for what could be causing this to happen. I was thinking of increasing my ph to 6.2 to help with calicium uptake.

 

[Rootbound]

Have you sprayed anything on them because all the damage seems to be concentrated at the end of the leaves?

 

[plantproblem]

No I haven't done any folar feeding.

 

[GRAPEGODaero]

Soiless but not hydro. 6.5 min. Raise it and see. By the looks it wont hurt them.

 

[GRAPEGODaero]

Test ur runoff you cant expect the ph of what u pour in to be the ph in your rootzone

 

[plantproblem]

my runoff has been anywhere from 6.0 - 6.2

 

[GRAPEGODaero]

Any organics in ur mix? If u answer yes bump it up to 6.5 maybe 6.8. If not maybe its burn.

 

[plantproblem]

nah its just pro mix with perlite added and all chemical nutrients.

 

[cocoJoe]

nah its just pro mix with perlite added and all chemical nutrients.

Big Bloom is organic..

 

[plantproblem]

Big Bloom is organic..

my apologizes cocojoe is right big bloom and bio root are both organic. I thought grapegod was refering to additives in the medium itself

 

[Papa Indica]

It kinda looks like a combination of P and K deficiencies. My 2 pennies.

 

[GRAPEGODaero]

there are several growing practices that are used in classic hydroponics that should not be used for soilless media. First, it is not necessary to use purified water (i.e. reverse osmosis). Secondly, while it may seem wasteful, always leach plants when watering. Finally, monitor soilless medium pH, not water pH.

 

[GRAPEGODaero]

Is it peat based pro mix? That would be organic

 

[tobh]

pH looks decent with room for improvment, feeding is reasonable. I don't see signs of any P def; my immediate thought was K or Ca def. There's no variagation (sp?) in the leaves, no scarlet-purple petioles or veins in the leaves. This is why I don't see the P def. May even have a little Mg def going on. Make up a foliar with some epsom salt and see if the yellowing improves over 24 hours. Since it's only on the lower leaves, my guess is it's not a mobile nutrient and I'm pretty sure Mg constitutes as a non-mobile nutrient.

In soilless, I tend to run a slightly lower pH of 5.8 going in as opposed to in the low 6's. Experience has just shown that 5.8 is a sweet spot and prevents a lot of lock out issues.

 

[kbellfoy]

I too use soil-less organic media. I never have my ph above 6.5. Ever. I range it from 5.8 to 6.5 to ensure full uptake of nutes but I find 5.8- 6.2 to be ideal. To get an accurate ph picture I use the slurry method. Never failed me yet that one. I also use bennies in my soil and brew teas. It's all about the bennies dude. That's where the magic is at. Read jumpincactus....he posts some amazing links to info. Try and find his thread on Quorum sensing.

 

[plantproblem]

It kinda looks like a combination of P and K deficiencies. My 2 pennies.

Ya I agree but I think it may be caused by an excess of calmag locking on the P and K I believe. At least from what I've read.

 

[plantproblem]

Check your ph meter to see if it's calibrated. This may help, also it looks like the issue may have already past give it a few days to see if the new growth is giving you the same issues. Ps looks like calmag problem to me for sure

Thanks for the reply. I calibrate my ph meter every other watering with general hydroponics calibration solution. And unfortunately these pictures are a few days old and things certainly don't seem to have improved. I've been told on another thread that it may actually be a calmag excess and that the excess calcium is locking on mag, p and K. What is your opinion on that?