Rapid die off at day 35 of flower... desperate for help

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Jul 4, 2014
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Hi community,

I have a very serious issue. For the past year, every grow I have starts to die off between day 35-42, and by day 56 is so far gone that my yields (and quality) have become are approaching zero. I have tried everything and am hoping someone here will recognize the issue and offer some help. It has happened across several strains, across several rooms, and with seeds, new clones, and my own clones grown in rooms that were sterilized between grows. My first thought was a fungus, like fusarium, (and it still could be) so I have treated them all with a root drench of 3 different classes of fungicides when flipped to 12/12. They grow well and look amazing for the first 4 weeks, then top bud leaves start to wilt and dry up. During week 5-6 this RAPIDLY accelerates until the whole plants leaves die and only the bud is left green. At this point I try to harvest what I can, but its usually not much and of poor quality.

My next thought was ph, and the last run I have diligently kept it at 5.8... still happened.
Then i thought it was nutrient level.. perhaps a shortage of something they rapidly start taking up during the height of flowering, and thus take it from their own leaves when its not available. So, i upped my ppm from 1400 to 1800. This also didnt help. (started to see some nute burn but not too bad)

Now, I dont flush between reservoir changes but.. i havent for 8 years and its never been a problem. So unless something has changed otherwise I dont think its that. But again, open to any thoughts.

Here are the details:
What Strain is it? Multiple, sativas seem to be affected more though

How Many Plants? 15
Is it in Vegetative or Flowering Stage? flowering
If in Flowering Stage... How Long? 35 days
ebb and flow hydro
If Hydro, Reservoir size? 100 gal
If Hydro, Reservoir Temperature? varies with season, 75degrees
If Hydro, what type of Medium? coco
If Hydro, what type of Setup? ebb and clow

Size (Wattage) of Light? How Many? (2) 1000w hps
Is it Air Cooled? yes
Temperature of Room/Cabinet? varies by season, every attempt made to keep it 75(day) 70(night)
RH of Room/Cabinet? 50%
PH of Medium or Reservoir? 5.8
Any Pests? fungus gnats
How Often are you Watering? twice per day, from and aerated tank
Type and Strength of Fertilizers used? cyco nutrients, 1400-1700ppm
Size or Square Footage of Room? 8x10 feet

View attachment IMG_6186.jpg
I don't grow hydro but I am pretty sure a reservoir temp of 75 is no good. What do your roots look like?
I never check the res temp, but it's room temp or colder. I've been successful growing for 8 years and never had an issue with res. just in the past year that things have started going south. That's why I thought maybe a disease? But I've treated with fungicides....
The ffirst thing I would say is that the flower space is under-lit, but that shouldn't cause that kind of leaf death to happen.

You said you are growing in coco coir in hydro. In my coco/hydro grows I must use Cal/Mag from the beginning of veg until the last couple weeks of flower. I know if I don't then they will struggle with ever worsening Magnesium/Calcium deficiency.
Do you use a calmag additive in your grows?
In total synthetic medium you must supply everything that the plants need to grow. If your nute regimen doesn't give the plants all of the micro and macro nutrients then they will slowly die back and struggle in some segment of the grow. Is your nutrients a synthetic or organic type?

When does this leaf "die-off" begin and what do they look like? how does it begin and where on the plants does it begin? These answers will tell us a lot about what is causing it.

You rez temps are definitely too warm for the plants' liking. You need to maintain 65f-70f for best results. I can't swear that the temps being that high are causing that but it could be one off several issues that are leading to your outcome.
those look like my plants now but mine were cooked when the air line came off the light and my tent got way to hot, but I cant see that happening over multiple grows.
imo ppm to high an your frying the plant and try lowering next time 500 ppm less but give it some N boost to help combat the yellowing
once I mixed pure worm castings with 50% perlite. all the fan leaves dropped off in early flower. I think 50% castings was too hot. never again. it pays to read up on this stuff.
anyway don't use 50% castings. too hot. never had dropping fan leaves problem again.
ive tried most mediums and methods. I like drain to waste as ebb and flow always seems to leave that nasty inch of water in the bottom. I was using 5 gal bucket inside another 5 gal bucket. that 2nd bucket had a single 1/2 in drain tubeing near the bottom.
after 25 years of this with ok results. I tried drain to waste by using a 3.5 foot long 18 in wide 4 in tall clear plastic tub and attached a drain tube to that. I can put 2 5gal tubs in each of those. wish I had figured this out many years ago. but an inch at the bottom didn't seem like much of a problem. I was organic but going back to 3pt gh. also using only coco this try. needs rinsed well tho. rinse at least 3 times. color changes to almost an orange. its clean. since I drill about a hundred holes in the single 5gal bucket. it dries fast enough so as not to worry about overwatering. im liking coco.
The sativa heavy strains I have would be dead at 1400-1800 PPM. At flower time, I let them creep up to maybe 1100 tops. During veg, I keep them close to 800.

I've got an indica heavy strain that I took up to 1600 once, but the leaves were burning pretty badly, so I keep them no higher than 1300 tops. YMMV.
Tell me more about your water....

Rez temp... arreation....source.

Coco and no calmag? That's a problem...

We need more info but I think it boils down to the water/solution your feeding with.

I have run strains in high ppm..and some take way-way-way less.
no more leaf drops when reducing wormcast content in mixes.
I shoulda read more. me dummy
i can edit now...!!??
anyway, i again switched from gh-3pt back to EJ organics for coca.
too much positive feedback about organic coco, drain to waste.
i read it gives top quality. golden. if some of my posts were impolite, im sorry. no more.
I am not sure how successful you are going to be going to organics after feedingchemical nutes. The chemical nutes would have killed any of the microbial life that you had gong on in your soil. Anyone more versed in organics who can advise on going organic, chemical, and then back to organic?
Sounds like he has already done it so... but you are right THG, maybe not every single beneficial microb would be killed, but most is my guess. If you want to go organics next time start out that way and stay that way.
If referring to my growing, I made the switch between grows, clones.
im loving organics. I haven't had problems by following a couple rules.
1. Light neem spray preventively maybe once every 10 days.
2. keep it clean and airflow/temps
3. enjoy life, be safe and watch the PH a little.
im loving sesame cannaoil lotz. Hushpuppy rocks.
Yes, ricky, I was talking about your grow, but apparently I misunderstood as I thought it sounded like you were going organic, chemical, and then back to organic on the same plants.

I would stop with the Neem spray. I simply do not like Neem oil, have never actually found it to prevent anything, and the oil can clog up the pores of the plants if you are using it every 10 days. I really do not recommend spraying plants with anything unless you have a deficiency to correct or a pest infestation that you need to deal with. If you want to do something preventative, get some SNS 209.
The effects of effecting the effectiveness of any effect, cannabis, cannabis, cannabis, in effect, can be effectively ascertained in an effective way.

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