yellow spots from the start

[Tranquilidade]

This plant showed yellow spots on the leaves almost from the start. Wondering what may cause this?

Tent temperature:
Days average: 26°C - 28C° or 80°F (30% humidity)
Nights average: 18°C - 20°C or 68°F (85% humidity)

Light cycle:
18/6

Soil:
Regular compost with 20% perlite

 

[TanzanianMagic]

From a distance it looks like a mite infestation.

https://images.squarespace-cdn.com/...nnabis_Cranshaw_Ed_Rosenthal.jpg?format=1000w

https://www.edrosenthal.com/the-gur...prevent-and-get-rid-of-mites-on-your-cannabis

 

[Creeperpark]

Regular compost is the problem if that is what you are using for a substrate. When you use compost as the main ingredient the pH will most always be high compared to peat. Compost is usually neutral when it comes to ph and some of the nutrients will be less availble. However, when using compost with an acidic fertilizer the pH can be lowered with the fertilizer. .

 

[Tranquilidade]

Thanks, fellas. My suspicion was the salt build-up.

 

[Tranquilidade]

Here is another shot of a different plant. The yellowing starts to accelerate once the flowering begins.

 

[Creeperpark]

If you break the nutrient sequence with plain water the plant will turn yellow. Your plants look underfed and need nutrients however if the sequence is broken then you can only go with what you got at this point. Adding fertilizer at this stage will cause more problems than good.

 

[TanzanianMagic]

Here is another shot of a different plant. The yellowing starts to accelerate once the flowering begins.

This is a molybdenum deficiency/lockout. This plant looks like it is getting the wrong kind of nitrogen in flowering; nitrogen nitrate instead of ammonium nitrate. Mo is used to turn nitrogen nitrate into ammonium nitrate, so continuing to use nitrogen nitrate in flowering depletes Mo.

From Ed Rosenthal's Marijuana Garden Saver:

Molybdenum (MO)

Mo deficiency is rare, but is more likely to occur in color-changing strains in cold temperature conditions.

Symptoms

The middle leaves turn yellow. As the deficiency progresses towards the shoots the new leaves becom distorted or twisted. A Mo deficiency causes leaves to have a pale, fringed, and scorched look, along with retarded or strange-looking leaf growth. Older chlorotic leavs experience rolled margins, stunted growth and red tips that move inward toward the middle of the leaves.

Sometimes Mo deficiency is misdiagnosed as a N deficiency. However N affects the bottom leaves first and them moves up to newer growth.

Excessive Mo in cannabis looks like Fe or Cu deficiency.

 

[Three Berries]

This is a molybdenum deficiency/lockout. This plant looks like it is getting the wrong kind of nitrogen in flowering; nitrogen nitrate instead of ammonium nitrate. Mo is used to turn nitrogen nitrate into ammonium nitrate, so continuing to use nitrogen nitrate in flowering depletes Mo.

From Ed Rosenthal's Marijuana Garden Saver:

What about Calcium Ammonium Nitrate in flower and veg? I use ammonia for pH up in flower, sometimes Potassium bicarbonate but that really gets the ppm count up.

 

[Tranquilidade]

This plant never saw any fertilizer just water. However, I suspect temperature fluctuations and overwatering.

 

[TanzanianMagic]

This plant never saw any fertilizer just water. However, I suspect temperature fluctuations and overwatering.

Well it is winter, so temperature could be it. The pots should be an inch or so off the ground. I use folded crates, which are enough. It is just that it breaks the connection to the floor, which conducts cold like a current.

 

[Three Berries]

Well it is winter, so temperature could be it. The pots should be an inch or so off the ground. I use folded crates, which are enough. It is just that it breaks the connection to the floor, which conducts cold like a current.

I'm experimenting with bucket heaters set at 75F. Otherwise it seldom gets up to 70F or under 60F this time of year.

 

[f-e]

You didn't feed them.