Necrotic Leaves? What is the Cause!

from look and spread its calcium deficiency, in coco small doses of calmag is a must.

Mabe a Ca deficiency. Coco that is not properly buffered migth leach some Ca from your fertilizer -- this is temporary and will reach an equilibrium where it won't leach any more after that point. coco can be dangerous to use, FYI. it sure is convenient when it comes loose in a 70/30 combo with perlite, but then you deal with a bad bag or two of improperly buffered coco and you ask yourself, "why the fuck did i step on my own dick?" I've used 70/30 coco+perlite for previous 2-3 years years and have had a couple poorly buffered - this is lucky. If it's dog shit it will kill your plants or make the plants sickly AF. I'm going back to good ol promix plus topping off to 50% vermiculite/perlite composition with the spagnum peat moss component. Never a concern about leaching nutes or Na+ contamination etc. Safe and boring. With 50% perlite or similar you have the same drainage and aeration qualites as coco. There is nothing magical about coco. it's not the best choice. You are in a soilless medium. you need to be fertilizing every single irrigation with 10% runoff - this is waste water, don't let it sit in its piss. that water can be used on plants in the ground outside, but not potted plants, or toss it down the drain. Fertilizer should be cheap. If it's more than 4-5 cents per gallon, they ripped you off. By this point it should be full strength for sure, because full strength in this context is actually quite low. 1.3-1.5EC of well balanced nutrition (excludes what your tap adds to EC) is about all you need. N 120-130 P 40-60 K 180+ Ca 100+ Mg 75ish S 100+ Those ppm may vary based on what your tap water provides - likely a little mg and ca, i'd assume? maybe a ppm or 2 of other stuff, too. anyway, other variables will impact overall concentration, but these ratios are an excellent ballpark to start. This is only 1.3EC or so? Also, these are ppms calculated from guaranteed analysis lables. i'm sure there's an app that will do this for you. believe bugbee is linked to it? grow buddy? some shit like that? hydro buddy? anyway, there's more than 1 app out there that you can enter the %s from labels, dosage and it will tabulate it all for you. Or, make a spreadsheet like i did. You can feed at 1.3-1.5EC starting from seedling stage. It's no different than a fertile, but not hot potting soil. This will not cause a toxicity. I'm going to digress, but more about nutrient uptake below The other thing -- it is a myth that you sholdn't up-pot autoflowers. I've up-potted 400-500 times or more and yet to see transplant shock. You are far better off using an appropriately sized pot with your seedlings, and up-pot as the plant gets larger. you'll avoid things like mold on your topsoil. Unless you absolutely destroy the rooball with some retard strength, it's virtually impossible to cause shock from up-potting. All you are doing is moving the plant and sorrounding it with more substrate. It should not cause the plug to fall apart. This makes irrigation so much easier. with a tiny plant in a large pot you need to slowly water a larger circle around the plant -- still make sure it goes all the way down to the bottom. even then, it stays 'wet' for far too long. Same reason you dont' want to use water that's been stagnating for 3-4 days or more. If the plant cannot drink the water in a reasonable timeframe, it's just stagnating, rotting water in that pot. it's important to water fully to the bottom -- or in an appropriately sized pot you should make sure the entire things gets wet. And, 10% runoff as best you can while mitigating tiny plant / large pot issues. This is important to how it dries. if you water superficially, roots will turn upward instead of driving down, becaue there will be greater moisture above than below. Leaving dry pockets is adangerous game. As you increase width of irrigation (generally a bit wider than the canopy) you won't have to worry about that as long as you ensure some is dribbling out the bottom. you are overlapping the previous circle each time, so that is fine. if you cause dry pockets under normal conditions, you get an ebb and flow of moiture and any nutes that precipitate due to evpaportion wil be deposited there and go back into solution when it gets moist again... this can lead to a dangerous buildup. 10% runoff is essential to growing in a soilless medium. it maintains the equilibrium. the substrate will be a consent quantity after each irrigation. this means any issues you see are fixed through adjusting your formula and no concerns about buildup. if using good nutrients, pH is not a concern. one thing about measuring pH and runoff etc... do not expect it to be what you add to the substrate. it will be different for multiple reasons, and what oyu read off runoff will be different from what is actually in the substrate too. so these readings are only useful after you learn a baseline of the expected offsets you'll see while the plant is perfectly healthy and growing vigorously don't worry about that mold. As the plant's drinking capabilities catch up to the water capacity of the pot, you'll get a better wet-dry cycle that will prevent it from growing mold and alagea on the top. That mold is happening because it stays too wet too long with a tiny plant in a large pot. --------- extra infor on nutrient uptake I've done some very interesting reading on nutrient uptake. Common sense might say - provide nutes at the ratio in which they are used in the plant - which is how i used to perceive it, but this is wrong. Nutes enter a plant via 3 processes - physically bumping into the root is 1%,, but then there is mass flow and active transport. Some stuff enters more easily through mass flow and some has greater potential of entering via active transport - this occurs in our digestive system too. the long and short is you want "critical levels" of nutes in the solution (water+nutes) around the roots. The optimal ratio here has nothign to do with the proportional use in the plant. It's all about the stuff that needs to be actively transported (or at least a large portion to reach 100% of need) being readily available to be collected and brought back across root membrane. Now this is a study based on corn, but it will be very similar. the stuff that readily enters near 100% of need through mass flow will be the same molecules, even if the overall percentages vary a bit for this particular species. The same concepts are likely to apply. It may not directly impact how you read and react to the plant to adjust your formula (assuming you are honest about it, it's the same trial and error process and same path to the end result), but understanding it helps put things in perspective. Might avoid some bro-science or recognize someone trying to sound scienc-y but just making shit up as they go, lol. https://www.agry.purdue.edu/ext/pubs/AGRY-95-08.pdf go check out cocoforcannabis grow guides and posts in dr photon's corner. It will help you avaiod the bullshit that is out there, like "don't transplant autoflowers cuase it'll shock it." LOL, 400+ tranplants and yet to see it.. One time the rootball was a bit too dry and it fell apart on me, yet that plant still just kept chugging along without any shock. Easily avoidable. always do it sometimes recently after an irrigation.

No need to feed the plant at this point. Agree there is nothing wrong with the leaves

Your leaves are fine, but you water too often. You have mold on your soil and as a weed grower bacteria and mold is your biggest enemy. Water less often but bigger amounts. Let the topsoil dry out.