HELP! Please help me ID this issue with my baby!

[chipsandwich123]

What are these black spots on my plant? seemingly popped up overnight and has got slightly worse over the next 2 days. It seems to have spead to one of my younger plants too, I really hope it's not a fungus

 

[billyboy]

get your ph up a bit and give her some calmag.

 

[TOKABIGONE]

What medium are you in and whats your pH? I agree it's a pH issue but I'm leaning the other way if you are in coco.

 

[chipsandwich123]

in soil. pH was below 5 so I added some liquid lime and dolomite ( Ca as carbonate 41.5 % w/v, Mg as carbonate 6 % w/v) and raised pH of the soil up to 6ish if my probe can be trusted.

 

[billyboy]

I am a soil grower. FFOF and 20% perlite. I feed at 6.2 - 6.5.

When I have pushed the ph low (I blame it on the good weed) I have had the mottled brown spots. Not like yours that are all over all plants, but in a pot that got mottled and sick. My tap water is 8.5-8.8 untreated but I got too aggressive with the adjuster. A few days of H2O from the tap (short of a flush) and a little calmag and we could see clean new growth.

I do not believe that the medium is the big factor, she won't take up the cal if the ph is too low.

 

[OldManGrower]

I agree. Adjust your PH to 6.8 +/- and give it a little cal mag. Had the same exact issue myself.

 

[dilvish]

Could be magnesium deficiency but since you haven't provided much info all we can go on is the pictures. Judging by their maturity I'd say if it just started happening its a heat and/or root problem. a magnesium deficiency wouldn't occur that late in the plant unless you started adjusting your nutrient mixes. If it also looks like it spread to younger plants I'd go with root/heat issues.