Brown spots, please advise

Hi All,

I grew 4 plants (2x Dutch Passion Durban Poisen) and (2x Sannies Hammer Head). I grew in soil (mix of Ocean Forest and Happy Frog). It was basement grow under LED (platinum series lights) and fertilized with Bio Bizz nutes. I also added a bit of CalMag+ now and again. I watered with distilled water. Temps ranged from about 65 - 74 F.

Everything seemed to go well up until about a month before harvest. Then I noticed small brown spots that became more prevalent as the grow progressed and affected both strains. Can some of you more experienced growers please have a look and tell me what you think went wrong? I want to try and avoid this with future grows.

Thanks!

Citizen63

Im far from experienced, but that looks like some type of K deficiency/lock out (yellowing from outside in with brown spots). What line of biobizz are you feeding?

Hi,

It started with small brown spots. The general yellowing of the leaves only became prominent when I flushed with plain water before harvest. The BioBizz nutes used were Veg/Bloom/Topmax

Thanks

In other words I think the brown spots are a separate issue from the yellowing. I kind of expected some yellowing when doing the flush.

Citizen63 said:

In other words I think the brown spots are a separate issue from the yellowing. I kind of expected some yellowing when doing the flush.

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I just noticed you didnt have any deficiencies untill 1 month before harvest correct? Did you loose alot of yellowing leaves below before the upper fan leaves showed yellowing? If not then the yellowing was probably caused by a K deficiency/lockout. If you did have alot of yellowing leaves that later progressed to the upper fan leaves then that would usually indicate nitrogen deficiency assuming you have no root/ph/bug problems.

Biobizz is a soluble right? A flush will definetly make her use the stored nutrients instead especially close to harvest. Honestly the yellowing is normal that late in flower, but if you want to keep it green longer then try to give cal/mag only when needed especially if your using hard tap water, since too much can lock out K. Im new to all this so i cant tell you if its for sure a N/K lockout or deficiency.

From a thread on RIU.
Potassium – K deficiency is serious. It starts as yellowing patches that turn brown, then die and slowly consume the leaf. If the Ammonium, Calcium or Sodium (salt) levels raise too high, Potassium will be locked out. If the temperature drops below 50 degrees F, P can be locked out and it shows itself as the “purpling” of the bud tips and possibly leaves. Salts are sometimes (Sodium Bicarbonate) used to raise the pH level of a solution and this can lead to a K lock. Hydro growers need to carefully watch the salt build-up on their reservoirs and baskets (LICA balls and rockwool too).

When my father stopped feeding before harvest, his started to do the same thing.

The plants starving COULD make them more susceptible to deficiency? I'm just thinking aloud.

Glade no one said he needed calmag.

I'm having the same problem, a calcium def, and also grow under LED and never had this issue while my plants were under HPS.

So what does citizen63 actually have a Calcium or Potassium def

Bio Bizz is an organic fert that I only applied once a week. I used a Clabber auto drip watering system during the week. I am not so concerned about the yellowing I expected some of that. What concerns me are the small brown spots. I did have my lights too close for a while and wondered if they were burns from the LED's but I noticed it continued even after raising the lights. Perhaps I will try a different soil next time.

Oddjob said:

I'm having the same problem, a calcium def, and also grow under LED and never had this issue while my plants were under HPS.

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Do you not supplement a calcium to combat this?

If you use LED, getting rusty spots but supplement calcium "now and again" answered your own question.

If you use LED, getting rusty spots but supplement calcium "now and again" answered your own question

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Hi Budman, do you think its burn spots from the LED's? Anybody else have this problem with LED's?

Citizen63 said:

Hi Budman, do you think its burn spots from the LED's? Anybody else have this problem with LED's?

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Highly possible, pics would help.

pics would help

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?? Are the pictures in my original post not showing up?

take a read of this
http://www.thctalk.com/cannabis-forum/showthread.php?43148-Rust-Spots-on-Leaves-any-ideas

or could it be from spraying plant with some sort of nute

Calcium deficiency would be my guess by looking at the plants.

http://cdn1.buydutchseeds.com/media/wysiwyg/nevashhh/Calcium_Deficiency_in_Marijuana_Plants.PNG

Ph is to low.

OK, thanks all for the replies. Seems like the majority agree along the lines of calcium deficiency. I did use cal-mag (sparingly). I suppose I'll look into better calcium supplements on my next grow. Perhaps I will see if I can get some sort of powdered calcium to mix in with the soil when I'm filling the pots. I wonder if other people using Happy Frog or Ocean Forest also see problems with calcium deficiency?