Help! Yellow Spots appear over night

Hi everyone!
This is my 2nd grow of autoflowers. The plants are healthy (23 days) but yellow spots appeared today over night. I can’t really identify the problem.

There are also some very small whitish stuff you can see on the zoomed photo which make me think it is more a pest problem than deficiency ?

Climatic conditions:
Led light TS1000
29*C daytime
25*C night
Leaf temperature -4 to -2*C of room temp
Leaf VPD average 0.7-0.9 kpa
Humidity 58-68%


Soil = biobizz light mix + Bio Grow organic fert from green house feeding (3g/ liter substrate)
Only tap water

Any idea what it could be in the early stage ?

I think you are fine bug wise, just think they are starting to get some frost. The splotches look more like light burn from water droplets left on the leaf after an early watering

juansensor said:

Hi everyone!
This is my 2nd grow of autoflowers. The plants are healthy (23 days) but yellow spots appeared today over night. I can’t really identify the problem.

There are also some very small whitish stuff you can see on the zoomed photo which make me think it is more a pest problem than deficiency ?

Climatic conditions:
Led light TS1000
29*C daytime
25*C night
Leaf temperature -4 to -2*C of room temp
Leaf VPD average 0.7-0.9 kpa
Humidity 58-68%


Soil = biobizz light mix + Bio Grow organic fert from green house feeding (3g/ liter substrate)
Only tap water

Any idea what it could be in the early stage ?

Click to expand...

If this is isolated to a few fan leaves it’s @EhCndGrower grower mentioned “splotches” can appear by environment, dew, foliar spraying and may be nothing to worry. If this is a deficiency coming on you would see it in the lower area, or upper area, or everywhere (fan leaves).

Thanks for the answers guys
It was the only leaf (one of the first node) showing these brown spots. I just cut it away and I’ll see if it shows up somewhere else.

@calvin.m16 I thought about calcium too but the medium is fresh new and the plant only 23 days so it sounds unlikely no ?

This was an interesting read for me, who is brand new at growing. I also have some autos going but have yet to see anything like this. Please update this thread on how this turns out. Thanks!

Hi again guys, little update!
The small dots now disappeared after showing up on 1-2 leaves later.

9 days ago I top dressed with green house feeding bio bloom (3g/ liter substrate) since they started flowering.

Now unfortunately another issue is showing up and I can’t find any relevant infos on the web. The most affected plant is the white widow but it starts to happen to the cbd fix also. The newest growth is twisted/ corkscrewed and the tips are yellowish. It seems to get better as the leaves get bigger tho.

I measured the soil ph with a cheap soil meter (the yellow one with display) and it’s showing 5.5. Not sure if I can trust this probe but the tendency is def on the acid side.

Not sure if the twisting comes from:
- low ph and inherently nutrient lock out ?
- nutrient burn (nitrogen) due to the bio bloom overlapping with the bio grow already in the soil ?

I’m a bit worried as it already happen to me with another grow and I couldn’t find the cause..
Cheers

It’s 4-9-9 with 8 Ca and 4 Mg

They look over fed to me, or ec is to high in soil from them not eating. Do a slurry test and check ph and ec of soil. Go from there.

Thanks man. I guess I should have adapted the dosage of the dry fertilizer to the shorter life cycle of autos.
bio grow was for 8 weeks and top dressed with the bloom after 5 weeks already.

I don’t have an EC meter tho so it will be harder to diagnose nute burn..
But from the feeding I did it seems obvious