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

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
indoor
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

Poor ventilation will do that

As far as ventilation goes I have 1000cfm coming in one side and another 1000cfm exhausting from the other. It's plenty to keep the room cool, and never been an issue before.

Add ne new stuff... could be offgassing.. also how do the roots look root rot could cuz them to look that way...
Sativa do not need high ec at all i usually feedem around 800ppm max im known to push my plants but sativas dont like it...

G`day C22

This guy is the best at explaining what goes on with plants that I have read .
I suspect a root disease .

http://www.manicbotanix.com/hydroponic-grow-guide/root-disease-prevention-in-hydroponics.html

Thanks for sharin

EB .

Id guess just from the pic.... heat issue due to the light being to close. The branch in the back away from the light still has all its fan leaves intact(cuz its not burning) If your hand is hot when you put it at the top center buds .... id raise the light. Disease would kill them before day 35 of flower. if it were something that stays in the room it would attack and kill them young.

If that aint the case..... nute issues..... so check the runoff. They kinda look like they are starving for nitrogen. Again i highly doubt disease.

have you scoped for mites?

I took a second look. Lower leaves are nice and green..... so nitrogens prob good. Loosin leaves top down in center of tent =heat. Crispy burnt leaves loosing moisture in intense heat.

They grow good in veg.. you flip to 12/12 they shoot up 6 or 8 inches into dense heat....

Dont harvest early. The lower leaves should cary them thru.the buds still alive. The bud will start to turn a golden color if the plant is close to death (along with the stalk). They still got plenty of swell left before they are done. ..... id let it go and get some nugs.

Have you grown this strain without this problem? Are they from clones?

captinahab said:

Id guess just from the pic.... heat issue due to the light being to close. The branch in the back away from the light still has all its fan leaves intact(cuz its not burning) If your hand is hot when you put it at the top center buds .... id raise the light. Disease would kill them before day 35 of flower. if it were something that stays in the room it would attack and kill them young.

If that aint the case..... nute issues..... so check the runoff. They kinda look like they are starving for nitrogen. Again i highly doubt disease.

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G`day Captn A

Mid Summer . Has Fungus Gnats . Necrosis after 35 days . Only fan leaves burning .

Says problem with the roots to me . If it was heat I would expect the calyxes to bleach .

Pythium and gnats are often found together .

Thanks for sharin

EB .

Elmer Bud said:

G`day Captn A

Mid Summer . Has Fungus Gnats . Necrosis after 35 days . Only fan leaves burning .

Says problem with the roots to me . If it was heat I would expect the calyxes to bleach .

Pythium and gnats are often found together .

Thanks for sharin

EB .

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It seemed more than odd to me to that the bud looked perfectly healthy just the fans affected too. Ive never had root problems (knock on wood) even with fungus gnats. I run fox farm soil so im no stranger to the gnats. I get some in every bag it seems like. When i let it dry out good after the first water they go away.

I see he is running that coconut ... its banned from my garden (inferior junk)... how many time do normal people flood a day with coconut fibers? He floods 2 times a day.

If it's fusarium, you can break a branch that's infected and see if the middle is brown. With fusarium it attacks just like that. You can have a soil test done by a lab or take the bud for a mold test. Costs $$ but sounds like you need this identified.

EDIT: scratch the soil test since you're in hydro (well you might be able to since it's coco). Whoops! But that makes me suspect root issues even more. What's your source of water? How often are you using ph down/up? Water temp? I used to grow ebb n flow but quit due to root rot.

Coco holds water well. One watering a day if the pot is sized right for the plant.

crisco22 said:

I have a very serious issue. For the past year, every grow I have starts to die off between day 35-42

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Because of the timing, it sounds like a pre-flowering issue with lack of P and K.

You need to add extra P/K or bloomfood early enough, so that the pre-flowers don't run out of it.

To make sure it isn't lockout, you should first flush the medium, and then feed with a normal strength early bloom food.

captinahab said:

It seemed more than odd to me to that the bud looked perfectly healthy just the fans affected too.

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If it affects the (oldest) fanleaves, then it is a mobile nutrient defiency/lockout. P, K, Mg, would fit the bill.

G`day Captn A

The dead leaves / good sized nugs is what I`m going by .

If it was just nute def I wouldn`t expect such good bud development .

The 35 days after transplant is interesting . Is it some thing in the mothers ? Is it coming from the clone process or is it in the rez that feeds the plants or the water supply ?

Keeping the root zone between 18 -22 C will help with dissolved oxygen . The water supply should not be outside that range either .

Thanks for sharin

EB .

I dont know... i give up in the cannabis infirmary department.. i would have a lot better idea if i watched the whole grow and knew all the crap he was putting in it. One pic and one post doesnt really help.

I lost intrest at coco.... id rather grow in sanitized hobo vomit.

Ill let everyone else play the guessing game..... im out

Best of luck

Coco is as easy as it gets. If you can't grow in coco, you have bad coco, or you just can't grow.
As far as this case, I don't really see the problem. The old fans died. So what? They are supposed to die first. As long as the buds are good, that's what matters. Having said that, I would flush at least a couple of them and see if there's improvement. Sometimes you can get salt build-up in coco if the coco's crappy, or not rinsed properly, or from over feeding. When in doubt, flush. It can't hurt, and may solve the "issue". Pull one plant out of it's pot and examine roots, as Elmer suggested. That way you will know if it's a root problem. I suspect imbalance of nutrients due to salt build up and possible over feeding.

RetroGrow said:

Coco is as easy as it gets. If you can't grow in coco, you have bad coco, or you just can't grow.
As far as this case, I don't really see the problem. The old fans died. So what? They are supposed to die first. As long as the buds are good, that's what matters. Having said that, I would flush at least a couple of them and see if there's improvement. Sometimes you can get salt build-up in coco if the coco's crappy, or not rinsed properly, or from over feeding. When in doubt, flush. It can't hurt, and may solve the "issue". Pull one plant out of it's pot and examine roots, as Elmer suggested. That way you will know if it's a root problem. I suspect imbalance of nutrients due to salt build up and possible over feeding.

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I wouldnt know, ive never tried coco it may be the bee's knees. It just looks like wet shredded news paper to me. If im going to use an inert medium i would rather use air(roots hanging from net pots), then hydroton balls, then rockwool, then coco ... in that order. I dont think coco is going to beat growth rate of hydro. I just havent been bored enough to try it. I guess them coconut farmers will half to push their free waste products on someone else. I think its a fad like huge reflectors. If the co**** husk goes to the landfill. ...its biodegradable ...so i dont feel bad.
I read about overwatering and salt buid ups all the time with coco... i ran the same rez for 3 grows in a row with hydro. If feel like i would be downgrading to switch to it as a soiless medium.

And as far as the peat bogs are concerned i now use no till so im doing my part. To each their own... i got friends in colorado that swear by it.

crisco22 said:

Type and Strength of Fertilizers used? cyco nutrients, 1400-1700ppm

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There's your problem mate.