PICS - Yellow/Brown Spots on Fan Leaves - 4 weeks into flower

Hello All,

Fairly experienced grower here with a sudden, new problem on my hands. I have 5 Sensi Star and 3 Ice Cream females that are just under 4 weeks into flowering and just yesterday I noticed that the fan leaves on almost all of the plants have gotten yellowish/rusty brown spots popping up on them. The buds look fine as do most of the smaller bud leaves, but this is a new one for me and I'm hoping you can help. I'll go into as much detail as possible about the system/setup and let you give me feedback. This is the first time I've used this new RDWC system I built and everything was perfect until yesterday. The pics of the leaves below are shot from the underside of the leaf as it best shows the problem. One other note, I have been spraying every 2 weeks with neem oil to prevent powdery mildew and spider mites. If I had just sprayed, I would suspect the neem oil, but it has been over 2 weeks since my last spray and everything has been fine until yesterday.

-RDWC Hydroponic System with eight 5 gallon buckets and 27 gallon reservoir + 27 Gallon R/O top off reservoir. 67 total gallons in system (not including top of reservoir)

-960 GPH Pump

-Sunlight Supply Sun System - Super Spectrum 600 W HPS & 400 W MH Bulbs - Air Cooled w/glass

-740 CFM Extraction Fan with Can Carbon filter, in-line cooling of lamps.

-R/O Water

-Botanicare Nutrients: Pro Bloom / Liquid Karma / CalMag / Sweet

-Air Temp: Day 74 - 75 / Night 68

-Water Temp: 72 F (kept constant with inline chiller)

-PPM: 1200 - 1300

-PH: 5.6 - 5.8

I have suspected it may be a calcium or magnesium deficiency because I cut back on the CalMag applications, which I've normally never done, because I was starting to see slightly yellowing leaf tips about 2 weeks ago and I suspected early over fertilization. I added some CalMag yesterday but it's too early to tell if it will stop the spotting in its tracks. My 2nd suspicion is that it might be a manganese deficiency which can be caused, in part, by too much magnesium (locks out manganese from what I've read). Who knows? I'm going to do an approximately 30 gallon water change today and run fresh nutes with the suspicion that there may be excess salts which are locking out some nutes. I've never had this happen before in 6 previous grows.

Anyone??? Anything??

um.. im not a expert... hell im just a begginer... but... it kinda looks like heat stress or nuts burn? im not positive so dont take my word for it im just giving you what it looks like try asking if thats what they are tell me if im right =P

rollanotherblunt said:

um.. im not a expert... hell im just a begginer... but... it kinda looks like heat stress or nuts burn? im not positive so dont take my word for it im just giving you what it looks like try asking if thats what they are tell me if im right =P

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I don't think it's either of those. I've never had a problem when I keep PPMs at 1200 - 1300 in mid-flowering. Also, my air temps are always in the mid-70s so I highly doubt it's heat stress either.

alright well i tried but if i come across something that explains whats going on ill hit you up

really nice plants though

Nothing from any of the experts out there?

C'mon peeps! I don't get it...I write a very detailed explanation of my problem, thoroughly explain my setup, and include some relatively clear pics of the leaves and all I get is one reply from a newb (no offense to the newb) who thinks it's heat stress or nute burn (both of which it's not)

Please, someone! I've paid my dues here. Someone?

Buehler?......Buehler??

Im no help. I use soil. :-\ hope you figure it out though!

What's your ph at? It could be Calcium or Phosphorus lockout. Make sure you run you ph a little low on the acceptable scale and let it climb through the range so that your plants can get all the nutes it needs.

I hope this helps.

StreetRider said:

What's your ph at? It could be Calcium or Phosphorus lockout. Make sure you run you ph a little low on the acceptable scale and let it climb through the range so that your plants can get all the nutes it needs.

I hope this helps.

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Thanks for the feedback. I have generally been keeping my Ph in the 5.6 - 5.8 range as mentioned in my original post, but I occasionally let it "drift" down into the 5.5 range and up to the 5.9 range to make sure I'm getting broad elemental uptake.

Any other thoughts out there?

http://www.ganjaguerrilla.net/Album6.htm Hey check out this site, it shows many pics of plants with problems, it will probably help you out, I know it helped me. Good luck

I think I found out the problem and it just goes to show how you can get too relaxed with each successive grow. I tested my Ph meter and sure enough it was reading 1.5 too high, which means that I've really never allowed the solution to get up into the 5.9 range like I thought I'd been. When it was reading 5.9, it was really closer to 5.75. That means I was never hitting the ideal range for uptake of Phosphorus and Potassium http://www.gardenscure.com/420/attachment.php?attachmentid=128649&d=1116061394 I normally recalibrate my meters every month and every time they have "drifted" a litte. Sure enough, it was the case this time and I have no one to blame but myself. I think I caught the problem early enough and they've been soaking in 5.95 Ph for the last 24 hours. I'm going to keep the Ph at this level for a few days and gradually bring it back down to the 5.8 range. As a matter of normal practice, I always adjust my Ph in "waves" from as low as 5.5 up to 5.95 and back down again just so I know I'm hitting all ideal elemental uptake levels.

It drives me absolutely CRAZY when I don't do things perfectly. Those spotted leaves will continue to nag at me until harvest day, but I'll chalk it off as just another lesson learned.

My they are looking frosty now though. Especially those Sensi Stars. The Ice Cream is always very sugary, but this Sensi Star is showing the Ice Cream up right now. About 5 weeks to go and it will be clippin time!

how do you take care of a heat stress problem. We live in Texas and its always HOT. We keep them in a grow closet in an airconditioned room with fans on them at all times.

jcommerce, i have the exact same problem. i fear, however, mine is worse. ive been doing super skunk for seven years now. the prob. started about 2 yrs ago. ive been lazy about looking into it because i still somehow get my 1.5lbs per light. i also posted this concern two days ago with zero response. i'm new to the site, but i don't think there are too many "experts" in here. (not that i am one) if you have any thoughts you want to shoot back and forth, send me a message.

Hey bro, a lot of times an issue like this can be something small that could be overlooked...your plants could have a calcium or manganese deficiency..just my two cents

are your lights to close? Do you a spreader near the bulb? I had this happen to me once. Just about the time I was scratching my head over this, my hps burned out. I had to go back to t5 lights for a while. My new growth never had this problem.

dude i have th e same problem but im useing soil it just better but i dont understand it my ph is right but have brown spots aswell i add mag/cal but that has not worked so one is going to flash with clean water ph 6.5 i live in a good water place if u get a answer let me know happy growing dude

bro, alittle bit of yellowing isnt the end of the world lol. chill.