Help ID'ing leaf issues

Dobondobondo · Feb 4, 2018

Hey guys

So i must admit defeat and realise i cannot get rid of this issue for some reason. Can any of you guys help identify the issues with these leaves?
The spots etc started appearing a few months back and may or may not be related to an infestation of fungus gnats (Theres a picture below in case anyone can verify exactly what that bug is)

On the picture of the underside of the leaf, it seems like theres some extremely small white-ish dots, almost looks like tiny specks of sand. They dont appear to be moving (if they are, they move very very rarely as i havent seen any movement) and might just be a bit of dust from perlite.

And here's some pictures of the leaves

TrentL · Feb 4, 2018

Looks like potassium deficiency. Although it can be hard to tell magnesium from potassium sometimes, the initial onset (burnt edges and yellowing between veins) is similar.

What do you fertilize with? What did you last fertilize with?

Chilidude · Feb 5, 2018

Looks like a fertilizer burn to me, so back off with the fertilizer strength for now and those crystal/sand stuff you mentioned is Chlorosis (Edema) which is caused by overwatering.

The bug is called fungus gnat, you can catch them with a boul of watered down apple winegar, add few of those banana fibre things you peel off while eating it and one drop of colorless/odorless dishwashing soap in there too. Put that boul near your plants and the fungus gnats will just "love" it to death. :twisted:

Dobondobondo · Feb 5, 2018

TrentL said:
Looks like potassium deficiency. Although it can be hard to tell magnesium from potassium sometimes, the initial onset (burnt edges and yellowing between veins) is similar.

What do you fertilize with? What did you last fertilize with?

I use a 3.0 : 1.0 : 4.4 fertilizer on every watering. On average i'd say i water with about 0.5L once per week. To me that seems like a low strength fertilizer but then again this is my first year of growing
I was planning on switching to a 13 : 2 : 23 fertilizer i was given by the shop as freebie when i ran out of 3:1:4,4

I dont have any potassium to add manually atm but i could up the fertilizer strength

i do have a bag of epsom salt i could try and do something with if its magnesium?

Chilidude said:
Looks like a fertilizer burn to me, so back off with the fertilizer strength for now and those crystal/sand stuff you mentioned is Chlorosis (Edema) which is caused by overwatering.

The bug is called fungus gnat, you can catch them with a boul of watered down apple winegar, add few of those banana fibre things you peel off while eating it and one drop of colorless/odorless dishwashing soap in there too. Put that boul near your plants and the fungus gnats will just "love" it to death.

It could definitly also be fertilizer burn after looking into it. Annoying as hell that deficiency and overfertilizing looks exactly the same to me :/ Is there any way to distinguish the two except for just trying one of the two solutions?

I tried a variety of stuff for the bugs, they didnt seem to care too much for vinegar style traps but they definitly love the yellow sticky traps i've bought.

TrentL · Feb 5, 2018

The only easy way to differentiate them is to study the history of what you've used on them; if you haven't done any fertilizer then it's deficiency; if you have done fertilizer you've burned 'em.

I think you've overdone the fertilizer by a fair margin. I'd back off doing any for a couple weeks, at least, and let the plants recover.

Too much fertilizer can block uptake of necessary trace minerals, or vice versa.

I usually only fertilize two or three times during the entire plant lifecycle. After transplanting I give a highly diluted NPK infusion to help them recover from transplant shock. Otherwise I let the plant tell me the story of what they need. A lot of this depends on your soil mix though. If you are using store bought potting soil that already HAS slow release fertilizer in it and you shouldn't fertilize at all until the plants are telling you they need something!

Dobondobondo · Feb 5, 2018

TrentL said:
The only easy way to differentiate them is to study the history of what you've used on them; if you haven't done any fertilizer then it's deficiency; if you have done fertilizer you've burned 'em.

I think you've overdone the fertilizer by a fair margin. I'd back off doing any for a couple weeks, at least, and let the plants recover.

Too much fertilizer can block uptake of necessary trace minerals, or vice versa.

I usually only fertilize two or three times during the entire plant lifecycle. After transplanting I give a highly diluted NPK infusion to help them recover from transplant shock. Otherwise I let the plant tell me the story of what they need. A lot of this depends on your soil mix though. If you are using store bought potting soil that already HAS slow release fertilizer in it and you shouldn't fertilize at all until the plants are telling you they need something!

Its very likely they've been overfertilized if that is all you give them. But in that case a bottle of fertilizer would last me a lifetime o.O The instructions on the bottle also says to fertilize weekly for some reason but ill try going a month at least with no fert to see if it helps.

I should probably also add that the plants are indoor grows in 5-10L pots depending on the plant size. All the plants are watered from the bottom only to avoid mold on the surface

Chilidude · Feb 5, 2018

Dobondobondo said:
Its very likely they've been overfertilized if that is all you give them. But in that case a bottle of fertilizer would last me a lifetime o.O The instructions on the bottle also says to fertilize weekly for some reason but ill try going a month at least with no fert to see if it helps.

I should probably also add that the plants are indoor grows in 5-10L pots depending on the plant size.

My advise is to get one of those simple EC meters to measure the fertilizer mix. I would buy the best/easy to use and that would be the Bluelab truncheon but i think the cheaper Milwaukee cd611 EC meter would work too.

Dobondobondo · Feb 5, 2018

Chilidude said:
My advise is to get one of those simple EC meters to measure the fertilizer mix. I would buy the best and that would be the Bluelab truncheon. I think the cheaper Milwaukee cd611 would work too.

Aah the scientific way of doing it, definitly my preferred way

I actually work in a lab and have access to some more high end conductivity meters so i guess i wont have to buy one for myself. From what i can read in the hydroponics section they recommend EC values between 0.5 and 2 depending on plant size. would this be the same for soil based grows?

Chilidude · Feb 5, 2018

Dobondobondo said:
Aah the scientific way of doing it, definitly my preferred way

I actually work in a lab and have access to some more high end conductivity meters so i guess i wont have to buy one for myself. From what i can read in the hydroponics section they recommend EC values between 0.5 and 2 depending on plant size. would this be the same for soil based grows?

Use 50% less of the fertilizer if you use in a soil growing instead of hydroponic growing. So 100% values in hydroponic, but 50% values in soil growing, because soil is different and can be very quickly over fertilized.

When i use the max fertilizer strength in coco growing, it is only 1.6-1.8 EC in a greenhouse growing during the summer. Growing plants inside in coco, the max EC value is something like 1.2-1.3 EC.

Dobondobondo · Feb 5, 2018

Chilidude said:
Use 50% less of the fertilizer if you use in a soil growing instead of hydroponic growing. So 100% values in hydroponic, but 50% values in soil growing, because soil is different and can be very quickly over fertilized.

When i use the max fertilizer strength in coco growing, it is only 1.6-1.8 EC in a greenhouse growing during the summer. Growing plants inside in coco, the max EC value is something like 1.2-1.3 EC.

Im assuming indoor growing needs fertilizer more often than outdoors?

on another note should i remove the damaged leaves or just leave them on the plant?

Chilidude · Feb 5, 2018

Dobondobondo said:
Im assuming indoor growing needs fertilizer more often than outdoors?

on another note should i remove the damaged leaves or just leave them on the plant?

No, it is the other way around. Much less in indoor growing compared to outdoor growing as you cant bring sun inside the house and outdoor is much different too in comparison. Those damaged leaves will fall off in time, so just leave them.

Dobondobondo · Feb 6, 2018

Chilidude said:
No, it is the other way around. Much less in indoor growing compared to outdoor growing as you cant bring sun inside the house and outdoor is much different too in comparison. Those damaged leaves will fall off in time, so just leave them.

TrentL said:
The only easy way to differentiate them is to study the history of what you've used on them; if you haven't done any fertilizer then it's deficiency; if you have done fertilizer you've burned 'em.

I think you've overdone the fertilizer by a fair margin. I'd back off doing any for a couple weeks, at least, and let the plants recover.

Too much fertilizer can block uptake of necessary trace minerals, or vice versa.

I usually only fertilize two or three times during the entire plant lifecycle. After transplanting I give a highly diluted NPK infusion to help them recover from transplant shock. Otherwise I let the plant tell me the story of what they need. A lot of this depends on your soil mix though. If you are using store bought potting soil that already HAS slow release fertilizer in it and you shouldn't fertilize at all until the plants are telling you they need something!

Thanks for the help, starting out with chili growing isnt always easy but this site helps a lot

Im gonna start just watering (less often aswell) with no fertilizer and see what happens. if it gets worse after a few months of water only ill look into deficiencies.

TrentL · Feb 6, 2018

Get yourself even a cheap test kit and see what story the soil tells you.

In my 2015 grow I had P and K deficiency early on. The potting soil I'd used had sat soaking wet outdoors over the winter at a local big box store, and the slow release potassium and phosphates were washed completely out of it.

Trust nothing until it's verified.

Macronutrients are easy to test for with store bought kits. If those look fine, and you still have probs, you have something else going on you'd need a lab to examine the soil.

Damaged leaves will fall off on their own eventually. The big broad leaves act as storage for the plant, for water and other nutrients, so pruning them early will change the growth characteristics of the plant.

The most important thing here is the signs are present on OLDER leaves. That means your nutrients are still MOBILE. Those big leaves are still being used for storage, and nutrients are still moving around the plant (no nutrient lockout effects)

If new growth is affected, instead of old growth, you have nutrient mobility problems that are much more difficult to solve.