Rust colored spots on fan leaves

[Doc39835]

Problem: Rust color spots on fan leaves

Medium/grow method: Coco Loco in auto pots .

Feed: and supplements used: MegaCrop @ 3.5 grams per gallon...Bud Explosion @ 1 gram per gal....Sweet Candy @ 1 gram per gal. CalMag Pro @ 5ml per gal.

water source: Tap left to breathe for 24 hours then ph after nutes 6.2

Strain/age: 1 Cream Cookies and 1 LSD25 both by Fast Buds both going into week 6.

light used: AutoCobs 3 per plant at about 18 inches from canopy

Climate: Temps in low to mid 70s humidity at 45 to 55.

Additional info: I am currently bottom feeding into trays on the AutoPots as Ive had issues with the reservoir in the past. Ive used this exact same method on 3 previous grows with no issues and find I prefer not using the res due to wild ph swings and residue issues. The spotting began about a week ago.

 

[AutoWonders]

It would be helpful if you filled out the Infirmary form.

 

[4d-Rock]

Hey, it does kind of look like what I was dealing with. I’ve seen people diagnose cal-mag issues but also ph issues. I think when they kick into flowering it swings the pH quite a bit which may trigger this. With coco coir it should be pretty easy to flush and get back to reg nute/ph levels without shocking the plant too much.

I’m far from an expert but when using a complete nute like Megacrop there is limited things to try. Many people use it at the strength you are using and are doing fine.

 

[Waira]

- could be a few things, but at the core is this use of coco...when things so off in Autpots, you're in a pickle which is why i dislike coco vs true soil,.... because of the way coc behaves, so unlike soil and far less forgiving and flexible,.. run like a hydro nedium, it performs more consistently and is more easy to manage... You're constantly checking the pH and ppm going in and coming out, 15-20+% run off each time, no nute salts don't build up, and the coco's CEC is maintained --- (cation exchange capacity, coco is a huge Ca and Mg hog, until binding sites are sated, then it gives/takes readily)....
I see no info about you pH's, or ppm's,... without this it's difficult to assess if this is a nute lockout by off pH, or cumulative nute build-up (nute burn, and/or a competitive uptake issue), or plain old lack of, but more likely the former... too much
Symptoms look like P and K defc., maybe some micronutes kicking in too,... light distance is 18" from the top you say? ...looks strongly biased toward the tops? ...not sure what you mean by 3 COB's per plant; if literal, then the lighting is far too strong which can kick off all kinds of troubles, localized to upper zones.......

 

[Doc39835]

- could be a few things, but at the core is this use of coco...when things so off in Autpots, you're in a pickle which is why i dislike coco vs true soil,.... because of the way coc behaves, so unlike soil and far less forgiving and flexible,.. run like a hydro nedium, it performs more consistently and is more easy to manage... You're constantly checking the pH and ppm going in and coming out, 15-20+% run off each time, no nute salts don't build up, and the coco's CEC is maintained --- (cation exchange capacity, coco is a huge Ca and Mg hog, until binding sites are sated, then it gives/takes readily)....
I see no info about you pH's, or ppm's,... without this it's difficult to assess if this is a nute lockout by off pH, or cumulative nute build-up (nute burn, and/or a competitive uptake issue), or plain old lack of, but more likely the former... too much
Symptoms look like P and K defc., maybe some micronutes kicking in too,... light distance is 18" from the top you say? ...looks strongly biased toward the tops? ...not sure what you mean by 3 COB's per plant; if literal, then the lighting is far too strong which can kick off all kinds of troubles, localized to upper zones.......

By 3 cobs I'm referring to AutoCobs, the lights are used by many on this site and sold by Big Smo a member here. They are a lower wattage single cob light, and 3 per plant is pretty common. CocoLoco is the soiless medium I use but it is a partial coco blend and not 100 pct coco.
My ph going in is 6.2 and I've not checked run off, since I bottom feed with the AutoPots.
I'll give them a good flush as suggested. Thanks.

 

[Doc39835]

Hey, it does kind of look like what I was dealing with. I’ve seen people diagnose cal-mag issues but also ph issues. I think when they kick into flowering it swings the pH quite a bit which may trigger this. With coco coir it should be pretty easy to flush and get back to reg nute/ph levels without shocking the plant too much.

I’m far from an expert but when using a complete nute like Megacrop there is limited things to try. Many people use it at the strength you are using and are doing fine.

I will give them a good flush and see what happens. Thanks

 

[Dewey Matter]

By 3 cobs I'm referring to AutoCobs, the lights are used by many on this site and sold by @BigSm0 a member here. They are a lower wattage single cob light, and 3 per plant is pretty common.

This is something you've noticed as common? The economics alone place it in unreasonable territory at ~$350 of lighting per plant - are autocobs really only capable of producing 55 watts of power each (so driven by HBG-100 then)?

 

[Doc39835]

This is something you've noticed as common? The economics alone place it in unreasonable territory at ~$350 of lighting per plant - are autocobs really only capable of producing 55 watts of power each (so driven by HBG-100 then)?

So , running 6 lights increases my bill by 20 a month. I pulled 13 ounces from my last 2 plants. Not counting trim. I live in a state that an oz goes for 300.
Not trying to convince or debate but I'm pleased with the economic end of it.

 

[Waira]

I have them too, nice lights! usually 1/plant is good, so I was asking if you literally had 3/plant- ... seems unlikely, but in here, I gotta ask!
coco, blended with what? If you flush, you can't do it like it's reg. true soil, or you'll really screw up the coco's damn CEC, making matters worse, not better potentially,... and you must take pH and ppm's reading of run-off as you go, mainly to see if build up and/or off pH was the problem to begin with..
.... the flush solution recommended is: RO/Di water, with 150ppm Ca-Mg (to fix/preserve it bitchy CEC with Ca and Mg), plus another 150ppm nutes, pH to 6.0, and poured through until r-o is at or near input values,....

 

[Doc39835]

I have them too, nice lights! usually 1/plant is good, so I was asking if you literally had 3/plant- ... seems unlikely, but in here, I gotta ask!
coco, blended with what? If you flush, you can't do it like it's reg. true soil, or you'll really screw up the coco's damn CEC, making matters worse, not better potentially,... and you must take pH and ppm's reading of run-off as you go, mainly to see if build up and/or off pH was the problem to begin with..
.... the flush solution recommended is: RO/Di water, with 150ppm Ca-Mg (to fix/preserve it bitchy CEC with Ca and Mg), plus another 150ppm nutes, pH to 6.0, and poured through until r-o is at or near input values,....

I actually am running 3 autocobs per plant. I've never had any light burn and the plants are huge, at least compared to my earlier grows with 1 or 2 lights. I'll plead ignorance as I've only been at this for a couple years.