Id say root aphids. Been happening to a lot of people lately. Starts looking like a cal mag def, spots, keep treating it, leaves curl and die quickly, have to prop plant up, dies from the bottom up quickly nd then top gets spots at the same time. Theyre almost microscopic white root aphids too, forgot the scientific name but I lost my last grow with similar probs. almost couldnt see them with the eyeball, have to get a microscope.
I did a bit of reading on root aphids. I am not entirely clear on whether all varieties have wings as adults. I don't have any visible bugs. Nothing flying or crawling on the plants. I have inspected several leaves under an 80x dissection microscope. I don't see any sign of them in my tank or on my netpots. I am going to pull a root sample and look at it under the micrposcope.
As i said i went through an entire grow with sick plants and no explanation. Nothing was apparently visible. It wasn't until i happened to notice what looked like a microscopic speck of dust moving around the base of my pot that I knew something was amiss. Up until that point I was treating what I thought was a cal/mag def with no improvement whatsoever. I was frustrated and completely stumped. Theres a lot of misinformation on these forums and others regarding root aphids. They are not new, but are a new phenomenon in the cannabis growers community. There are about 10 different root aphid species i am aware of. Ill post a link to my old thread so you can read my struggle and see if theres any information that might help you. Edit heres the link http://forum.grasscity.com/sick-plants-problems/1259666-root-aphids-thread-identify-destroy.html
I have scoured the leaves under the microscope and don't see anything on the leaves. I took a section of root and put it under the microscope. I see something I cannot identify but it doesn't look like any kind of insect. Take a look at the pics:
While paying close attention to the girls every day it is sometimes difficult for me to gauge changes. If I step away for a couple of days and there are notable changes while I am away the difference is much more notable. The last few days I have been somewhat distracted and have done nothing more than measure PH & TDS, top off with RO water and adjust PH. This afternoon I had time to sit and look closely at the girls and the problem is getting worse. I see more affected leaves and a number of leaves completely yellow except the veins. Also, I am seeing tips curling up.
Have you flushed them lately? I'm having the same problem and I'm thinking its because I waited longer than I normally do to flush. Just flushed them today to see if it gets better. I'll let you know.
Hey the flush worked! All growth after the flush doesn't show any signs of those spots. I definately recommend a good flush next time.
I'm having the same exact problem as you! Is it bad that I don't give a fuck? (really) I don't think ( I hope) It will fuck up my grow, will it? Don't know... I've been so obsessed with the grow I'm letting loose a little bit. I have the exact same symptoms as you
Based on pictures found online it kinda looks like slight Phosphorous or maybe a more pronounced Magnesium deficiency to me (or some combination thereof) which, either way, you seem to have treated properly. Definitely doesn't look like Calcium deficiency to me. Mostly because I think with Cal def. the spots would neither be so fine nor stay in between the veins. But that's my opinion Other than problems with nutrient delivery or pH, could it be that your strain is INCREDIBLY sensitive to the temperature swings between day and night? But that's a shot in the dark, isn't it? Just trying to think outside the box. In the spirit of "playing doctor" (you show me yours, I'll show you mine) (or The Golden Rule if you prefer a less unsavory metaphor) please take a look at this thread and let me know what you think (in the thread) - your opinion would be appreciated. -n2p2k