Rust spotted leaves, curling under. Can't find an answer.

Hello all. I currently have a thread going in the CFL forum section following my grow. I am almost 5 weeks into flowering at this point and have just started dealing with plant problems. Within the last week I have noticed that some of the bigger fan leaves on my plant are developing rust color spots, have a very dry texture, and are starting to curl under a bit. I wasn't too worried about this at first but now it is starting to spread to the other leaves growing around my buds. I have done as much research as I can but I can't narrow this down to one specific issue on my own, so hopefully someone here can point me in the right direction. I'm using FFOF soil, with Big Bloom nutes only but I recently purchased some Tiger Bloom so that will be added during the next nute feeding.

Looks like spider mites to me.

looks like some ph problem there also.

first off how much are you feeding them?, if its not a spider mite problem then it looks like you are giving them too much nutes and blocking other key nutrients. such as cal/mag.
let us know if you see any mites, should not be that hard to spot. also let us know how much you are feeding your plants.
lu
if your not over feeding and its not mites then icy is bang on!

Soil needs to be at 6.7-7.0

420RedEyes said:

Well I did some more research and found out that I can use the PH up in my nutrient water before adding to plant. My only question with this is do I add enough PH up to bring it as close to 6.5 as possible? Or should I get it a little higher than that to help raise the PH of soil a little more?

Click to expand...

You cannot (dramatically) raise or lower soil pH by watering with pH up/down. How did you check the pH?

I took a few samples of soil in test tubes, mixed in some distilled water and let it sit for a few minutes. Then I took the water from the test tubes and tested them with some wide range PH test solution. I know it's probably not the most preferred way for testing soil, but it's all I can do until I get a new meter.

So you're saying I can't use the PH up to raise it by even a point or so? What should I do then?
Thanks again for the help everyone.

420RedEyes said:

I took a few samples of soil in test tubes, mixed in some distilled water and let it sit for a few minutes. Then I took the water from the test tubes and tested them with some wide range PH test solution. I know it's probably not the most preferred way for testing soil, but it's all I can do until I get a new meter.

So you're saying I can't use the PH up to raise it by even a point or so? What should I do then?
Thanks again for the help everyone.

Click to expand...

In all likeliehood your soil pH is fine. FFOF is pH corrected by the manufacturer. It's good practice to make sure your nute solutions/water is pH adjusted though. This will help prevent problems down the road. Soil needs to have its pH adjusted before you plant in it. You need to use something like dolomite lime or gypsum though. Just running pH adjusted water through the soil will not change it very much if at all. Now, over time the pH of the soil will usually drop as fertilizer salts accumulate but it's not usually very much of a swing and it happens very gradually.

We can hope!

A pH issue would be easy to resolve and is very likely if you haven't been checking your solution.

The spotting looks like a mixture of both issues but could be just pH if you are lucky. If it is off, flush that plant with a 6.5 to 7.0 pH solution until what comes out is nearly the same as what goes in.

Snow Crash said:

We can hope!

A pH issue would be easy to resolve and is very likely if you haven't been checking your solution.

The spotting looks like a mixture of both issues but could be just pH if you are lucky. If it is off, flush that plant with a 6.5 to 7.0 pH solution until what comes out is nearly the same as what goes in.

Click to expand...

A pH issue is easy to resolve in soil????? That he's already growing in??????? Interesting..............

He's only been giving Big Bloom (weak organic fert) and water. Neither of those has an extremely low pH and shouldn't cause that much of a swing in soil. I rarely even check my pH when I water and I NEVER have pH issues (in FFOF, of course).

420RedEyes said:

Okay great. Thanks for the tips guys.

I mixed up some big bloom(3tsp.) and tiger bloom(2 tsp.) in a gallon of distilled water to get it ready for the next watering, checked the PH and it said it was only around 3 or something ridiculous like that. So I'll start being better when it comes to checking the solution.

Click to expand...

Sounds a little low, but I don't know where your tap water is starting at to begin with. If accurate, it could definitely be an issue.

My nutrient suggestion to you is to use:
2.5ml of 6-4-4 Grow Big (1/2 tsp)
5ml of 2-8-4 Tiger Bloom (1 tsp)
10ml of .01-.3-.07 of Big Bloom (2tsp)

This will set you up with a 1-2-1 ratio of nutrients somewhere around 500ppm/1.0ec. You could definitely benefit from a touch more potassium, and given the low pH, DynaGro ProTekt Potassium Silicate will act as both a supplement (K and Si) and a pH up replacement. The stuff is used at around 1-3ml per gallon, so it lasts a long time.

The FF nutrient line is notoriously low in Cal-Mag so don't underestimate the power of a simple dolomite and guano top dressing tilled into the top inch of the media and watered through. Also, given the period of growth you want to start evening out the magnesium ratio a little, so a 1/4 tsp of epsom salt wouldn't hurt either.

All this after balancing the pH via flushing of course. The dolomite will be important after that to rebuild the pH buffer and balance the CEC.

I'm not a fan of tap water. I just buy distilled water by the gallon at the grocery store, pretty cheap stuff.
I got the PH of my water up to a normal range. I've honestly never heard of using epsom salt before, but it seems like a good solution to mag def.

And just to be positive, adding the 1/2tsp. of grow big isn't going to screw with anything this far into flowering will it? I only ask because I thought it wasn't supposed to be used during this stage.

It's all about ratios. Yes, you can use it.