Hello, I’ve been growing for a year in aeroponics, encountering every kind of problem and lately relating them to overfeeding.
Something is still bothering me, since the last two cycles I’ve had superhealthy plants, with a very extended root system, always bright white, the yield was fair enough for my standards, but leaves started to show rust spots starting from the lower branches and slowly reaching the top fan leaves. I thought it could be a cal/mag deficiency, but using a Calcium based fertilizer and others containing magnesium have brought no results. These two autoflowering (fast bud) have ended up worse than others i grew, so I hope they’ll be a good example. Furthermore, I’m growing in the same system a feminized Black DOG, which is about two months old, maybe more, but it’s just beginning to show the same spots on a few top leaves, while two clones, about 3 weeks from rooting, are growing just fine.
I know it’s a mess, but I had to, and beyond any expectations, they are living together just fine. pH, EC and fertilizers were based on the two fast buds life cycle, so they had plenty of PK in flowering and the last two weeks I lowered EC from 1,3-1.4 to 0.7-0.8 mS.
Leaves curling upwards normally means overfeed or heat stress or both. Doesn’t explain rust spots though. Maybe following this grow clean everything thoroughly in case you have spores of some fungus in there. They look close to finishing and the one in the back looks healthy so could just be about getting your grow dialled in better. Underfeeding is best ime. Less is more sort of thing so that you can add rather than have to rectify over feeding - is often harder once plants are over fed. I grow in soil but hydro peeps will probably have seen this before. Only other thing I can think is if you are using different nutrients together (only if) just check they can be used together. I’ve seen worse and looks like you’ll get some nice bud as long as you flush well. Good luck!
They have been underfed for a week or more, while I was away for Christmas holiday. I’m following the rule “if ec goes up i add fertilizer, if goes down only water”. High temperatures could be a good point, but I don’t understand why usually old lower leaves begin to show damage, and then it spreads to younger leaves. Younger plants don’t show this kind of problem.
I also usually get purple nerves and stems on most plants, but is this really a phosphate deficiency signal?
That’s why I add only water to the tank, to dilute the solution. Tap water has EC about 0,3 in my area, so adding 5lt I can usually lower EC by 0,1-0,2mS over a 1,2-1,3mS, 35-45lt reservoir.
Got it. A bit confused because earlier you said “I’m following the rule “if ec goes up i add fertilizer, if goes down only water”.”. I think it might be backwards haha
rust spots can be several things - including a magnesium problem.
The deficiency symptoms first become visible in cannabis after 4 – 6 weeks when small, rust brown necrotic spots and/or cloud-like chlorosis appear under the flowering top on the middle-aged leaves. The color of the young leaves and the development of the flowers remains normal.
What kind of aero setup are you running?
Almost forgot - what is your PH at? Are you using RO water or tap?
It may also be a calcium excess, I’ll try to balance it out with some magnesium only fertilizer.
I’m running on an Amazon 16 slots aero setup, always on. The solution temperature is always above 20 °C, pH between 5,7 and 6,2 in flowering, EC starting from 0,8-0,9mS and reaching 1,3-1,4mS. I’m using tap water, it’s almost straight from the mountains, with no chlorine at all, EC usually 0,35mS.
I use 3 LED panels for a total of 500W power draw, but the third kicks in only the last week’s. Box temperature ranges from 20-22°C to 28-29°C, with RH at 60-70%.
Last cycle I used GHE flora line, using less grow and more bloom and micro, to limit nitrogen and therefore excessive elongation. Enzymes are from cannazym, mycorrhizal fungi from TNC. I’ve always had rust spots, more or less, with high and low EC and a variety of fertilizers, so I don’t really know what’s the problem.
just out of curiosity how cold was too cold. My leaves are getting a light green to yellow in less than a week and i’m wondering if my tent is getting too cold.
Could these be causing problems to the leaves? They’re tiny flies, but 2-3 times bigger than those little flies usually found on rotting fruit. I thought they only bite animals, like mosquitoes, but they’re coming out the aeroponic system, both the tank and the root box.
Are they harmful for roots?
Anyway, I sprayed the plants with pyrethrum and and white oil (low molecular weight mineral oil which kills eggs and larvaes by asphyxiation).
Some leaves show signs of miner bugs (that’s what they call them here), they leave a trace of their passage, like mining through the leave. Not very much damage, but may it be related to the drain flies?
I don’t think they will ham the plants directly but they could mess with your system. Clog things up, affect pH etc. They are a sign you have build ups in your system that need cleaned out because that us what they feed on.
I think I can affirm that it was indeed a mag deficiency, after changing the solution and with a robust dose of mag containing fertilizers they recovered well in less than a week. After a week and a half I induced flowering, now they’re at 2nd week, beginning 3rd shortly and developing well, although some of the lower leaves are dropping down. Red veins on stems and leaves indicate a deficiency (like phosphate) or at this point is normal? Now I’m keeping pH at 5,9 and EC about 1,6ms, I got a few burnt tips, but they’re ok. Are the sugars contained in boosters like bud candy contributing to EC rising? Normally I keep at 1,3-1,4ms, but with mineral fertilizers, using tap water.
