Yellow spots on leaves

[JoshPo]

(Sorry, posted previously on another forum)

My plant is two weeks old. indoors, on soil were under 24 hr/day light (mainly to keep temp. high enough during cold nights). Plant looks good except for the spots. Couldn't really find any picture that looks the same in the (great!) sticky article at the top. I don't believe it has to do with nute deficiency as the soil is freshly bought and the plant is young. Please have a look at the gallery:

JoshPo Gallery - 420 Magazine Photo Gallery

TIA

 

[josh223]

Welcome to the community JoshPo.

I believe what you are seeing is the result of that one leaf getting wet during watering.

 

[donpaul.p]

its hard to tell by the pics but do all the leaves have these spots on them,

are you spraying the plants with water at all, if you are then this can cause the problem your having,

 

[CronicHempHog]

that would be some weird looking nute burn if it is

 

[donpaul.p]

i agree, nute burn starts at the tips of the leaves and slowly works its way further into the leaf, so im wondering if its just water damage from spraying the plant while its to close to the lights, i think i can see the same yellow spots in the other leaves as well but hard to tell from the pics.

check to see if your getting any water spraying out your drip pipes, the only time i had nute burn that looked something similar to that is when i sprayed my plants with nutrient water, i sprayed the plant with the full dose instead of using 1/4 of the regular dose to foliar feed with, so thats the only time ive had something similar happen.

 

[josh223]

The only other thing I've seen that looks remotely similar, with the tips not affected, is mites. Since it only appears to be affecting a single leaf, which appears to be in contact with the soil, I think it's water splash.

I've defoliated similar looking leaves on 46 of my own plants in the last half-day. They were all on the bottom of the plant, in contact with the media, and I know that I was getting them wet while watering.

 

[JoshPo]

Thank you all!

I hope it's just a case of water generated burns, although I have my doubts - never sprayed the plant, and I don't recall any water spilling on the leaves, but I may be wrong. For those who asked, it's not just one leaf, but the one in the left picture is the in the worst state (the right photo shows more leaves with spots, if you look carefully at the large leaves mainly near the ground, especially teh two opposite to that one).

I checked the bad leaf for insects, but nothing is shown under the magnifying lens, both upside and downside are free of any visible creatures. Can it be some microscopic fungi? If the problem will worsen, should I try some fungicide even as caution measure, or is fungicide harmful to the plant and should be used only when it's a definite must?

Thanks again, you are great.

edit: Pic of the down side ...

 

[KingJohnC]

Your leaf damage appears to be a deficiency or nutrient lockout. How many millilitres or teaspoons per gallon and of what are you feeding your plant? Is your water soft or hard? What are you adjusting your waters pH to? You want pH 5.8 for hydroponic and soiless (peat moss and coco coir) and pH 6.5 for soil. When did this problem first develop? I use 18/6 18 hours of light and 6 hours of darkness for my vegetative lighting cycle. You may be able to change your lighting cycle so the light is off during the warmest parts of the day and on during the coldest parts of the night. I read a thread on lighting cycle versus root length and plants grown under 16/8 grew the longest roots, 18/6 was not tested. I was made aware of a study of lighting cycle versus plant growth and plants given at least 5.5 hours of darkness grew the most.

here is a nutrient availability chart

here is a cannabis leaf deficiency chart

here is the Cannabis Plant and Pest Problem Solver and the Plant Abuse Chart

Cannabis Plant and Pest Problem Solver - Pictorial

Plant Abuse Chart

 

[JoshPo]

Your leaf damage appears to be a deficiency or nutrient lockout.

Thanks. The spots are not spreading to new leaves so I give it a rest. Just started to add a fertilizer (BIO-GROW by BIOBIZZ) to but I doubt it has anything to do wuth the problem as soil was rich in nutes to begin with, the pot is large and the plant still young.

 

[KingJohnC]

What are you adjusting your nutrients pH to?


here is a BioBizz nutrient feed chart