Rust colored tips and spots

Hey everyone,

So my plant recently started showing rust colored tips and spots. Would that be nutrient burn or a deficiency?

Currently on day 23. The plant seams to be flourishing but more of the tips are getting the rust color.


Looks like it’s maybe a case of Septoria which is a fungus that happens when air isn’t being properly circulated. It also may be a calcium deficiency so we need more info from you to zero in on the issue. At least a fan needs to be added. I run two 4” fans 24/7 from Veg through Flower.

A. Close up pic of stem
B. Clear pic of nutrient bottles so liquid levels are visible
C. Pic of roots
D. Overall day and night air temps
E. RH levels
F. Reservoir water temp
G. Is the cocoa pod wet to the touch

The good news is that we have seen this many times and it is easily correctable so no worries fellow grower.


The stem gets thinner going into the ground. I broke my camera so not the best pictures. Air temps around 22.5
Water around 24 not sure on humidity.
Cocoa pod is moist to touch.


Looks like you have a case of dampening off so asap you need to introduce a fan to get the cocoa pod dried out. Second I recommend you carefully push the cocoa pod up 3/4 of an inch. It will be sticking up and not flush with the lid and that’s okay. Don’t waste any time, get on this.


24 degrees is also a little warm for water temp. You want to keep under 21 degrees. If you can’t with temp I recommend getting some Hydroguard. It is a chemical that allows higher water temps without needing a water chiller.


Hydroguard on the way!
Good call too, just noticed for some reason my unit filled to top when did drain and fill this morning. Way too much water in there.

So the dampening off is causing the rust colored spots as well?


In a way both issues are being caused by dampening. The thinning of the stem is common in the grobo and the spots seem to go hand and hand pretty often. I don’t know the exact science behind it but have read enough threads to be able to recognize it. The spots seem to stop when the grower gets the fan, raises their cocoa pods uses some and hydroguard. Good luck!


Sweet thanks a lot! Got quite a bit of reading to do on these threads!

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So far So good :+1:

Read this one. In the middle of the thread he goes through the same thing.