Please Help! I've Tried Everything, Rusty Autos in Flower!

[ojuyn]

Hey AFN Family, I haven't made a post since 2013 I think. So it's good to be back!

Here's the situation, I haven't grown indoors in ages and decided to start again. When the autos hit flower they start to get rust spots on the leaves that slowly crawl from the bottom up. I've spent hours researching and trying to adjust things over the past couple grows but still no luck.

Light:
18h/6h - BP2500 @36" above the canopy. getting 450ppfd+/- at canopy. DLI of about 30.

Feeding:
Remo Nutrient line @1/2 Strength:
Micro - 4ml/gal
MagNifiCal - 4ml/gal
Bloom - 4ml/gal
AstroFlower - 4ml/gal
Nature's Candy - 4ml/gal
VeloKelp - 2ml/gal
RO Water
Final solution @800PPM Ph of about 6.2-6.4

Medium:
Promix HP in 3Gal Fabric Pots.

Environment:
Lights on = 72-75°f and Humidity @30-40%
Lights off = 67-70°f Humidity @35-45%

Okay so the first 4 photos are an Auto Chem OG at Day 80 *I don't plan on fixing her at this point lmao* she has gotten progressively worse since about day 40-45.

The last 3 pictures are an Auto Amnesia at Day 60 starting to show the same rust spots.

I tried dosing heavier with Cal Mag the last grow, I've tried upping the Potassium, I've tried Flushing and Ph-ing the soil. I'm starting to lose my mind. Last runoff check was 900ppm and Ph of 6.0.

Any ideas everyone?!

 

[Cannaficionado]

I dont grow hydro, but I know rust spots can come from a couple things. Mag deficiency in late stages from the look of the leaves. But magnesium is dirctly effected by phosphorus. If you have too much phosphorus in your nutrient mix, it csn lock out both calcium and magnesium. Too much phosphorus can actually lock out a bunch of stuff.

Maybe you have something in there really phosphorus rich in your nutrient mix or have some kind of build up or something.

Refer to this chart. Mulders Chart if you wanna look it up.

Solid lines show which nutrients are locked out by excess of another, and dotted lines show which help uptake of another. Theres a few that have arrows in both directions, I think that means both have to be in proportional amounts to eachother otherwise they effect eachother the same way in the wrong levels.

Your buds look great though.

 

[bearhair]

Too much calcium can also cause a mag lockout. Try an Epsom foliar spray and cut back on the magnifical. May need a flush to reduce the calcium buildup in the promix..

 

[Shugrows]

Im having the same shit man. Except my soil ph is really low locking everything out.

 

[bearhair]

Im having the same shit man. Except my soil ph is really low locking everything out.

I'm working on my first promix hp grow with grow dots and am having an issue I haven't seen before.

 

[Shugrows]

I'm working on my first promix hp grow with grow dots and am having an issue I haven't seen before.

Tired that 2 times. Wont do it again. Stunted a plant and the other was n toxic through out all of flower.

 

[bearhair]

Tired that 2 times. Wont do it again. Stunted a plant and the other was n toxic through out all of flower.

Great... goin back to coco..lol

 

[Nadnerb]

I originally started growing in soil but way too many issues with PH and PPM's. Switched to coco and Autopots and it's much better and easier to correct issues.

 

[Cannaficionado]

I originally started growing in soil but way too many issues with PH and PPM's. Switched to coco and Autopots and it's much better and easier to correct issues.

You really dont have to worry about dissolved solids with soil. Ive never used grow dots with weed which is probably where the issue was. Ive never liked slow release fert dots. They all dissolved at a different rate and almost always cause issues no matter what I was growing. Always used them according to specs. But once the roots hit them its basically sucking on a nutrient ball.

For me its easy, doesn't really matter which soil you choose to use as long as it meets the needs of the plants roots. But if its got food in it already you probably wont need ANY nutes for at least the first 4 weeks after that buy a liquid fertilizer line and feed according to sched. You might have to experiment with dosages but once you get it thats it. Best to pair soil with their nute line.

But either way, if coco is working better and thats what makes you comfortable stick with it. No need to struggle if you already got a firm grasp on a method. But I understand trying new things.

 

[bearhair]

With coco in a utopots I had a nutrient salt build up in the coco that caused issues. Solved it by top watering to a 20% runoff once a week. Then started just top fertigating. Might want to check out coco for cannabis.. lots of good info..