rapid die off at day 35 (flower)... 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

What are your roots doing? That rez temp is pretty high. What is your water source?

Bugeye said:

What are your roots doing? That rez temp is pretty high. What is your water source?

Click to expand...

Source water is just municiple tap, res is at room temperature. I will have a look at the roots today and see if anything odd is going on, but in past harvests they were all ok root wise. The res temp fluctuates but it has for 8 years so I dont think that would be the issue. Does anyone here have any thoughts on Cyco Nutrients? Maybe I need to switch back to GH or Cutting Edge?

Well I got a few thoughts...
First, have you tried different nute companies or
Mediums? Do you use RO water or have a ppm of less than 100 coming from your tap?

If doing ebb and flow try switching to hydroton or rocks since this will limit disease and improve aeration. How big are you pots? Have you inspected the roots? What fungus are you seeing? Do you aerate your reservoir? Do you have a chiller for the res? If not, they are also probably rising during the day and causing bacteria growth and root rot.

Treating a plant with a bunch of chemicals when you have you idea what's wrong with it is only asking for trouble. If you are using cyco, do you use their zyme? Also you need to have your ph fluctuate. Keeping it stuck at 5.8 religiously will prevent the plant from up taking key nutrients.i normally drop down to 5.6-5.7 and let it rise to 6.2-6.4 depending on strain and then drop it back down again. Every strain is different but you should see better results regardless. As it gets closer to weeks 7-9 depending on indica vs sativa I would start to keep ph below 6. I had a sativa do that once from low nitrogen and high water temps.

I have virtually no experience with hydro but feel pretty confident telling you that something in your water is causing this..possibly the water itself.

You have obvious experience growing. Have you moved to a new location where you're now using a different water source or a different altitude or humidity level contrary to your previous experiences?

The way the leaves are turning brown is certainly not because of a nutritional overdose or deficiency. With 8 yrs under your belt, you trump most people here, I might ultimately suggest trying a new strain.


Good Luck , Bro!

those looked burned of some sort, also running ebb and flow here and don't have anything like that going on... what kind of nutrients are you running? what is the room temperature? is it well vented with fresh air or are you feeding co2 at a level you can monitor? are you running an airstone in your reservoir? (if you are, stop, ebb and flow systems naturally oxidize fine and the airstone will just mess with your ph and nutes).. is any of the water being exposed to light? reservoir lacking a lid or during flood cycles? they're all obviously dying exactly the same way so there must be some root cause here to this sudden death around week 6

The strain I'm running requires cal/mag on top of my tap water starting at around week 3 flower. By week 6 I'm adding 3ml/l calmag. I figure it's just a heavy calcium eater and maybe yours is the same... I didn't see you mention if you use it

I run lucas up to 1100 ppm with the calimag additive and the other additives from gh, but didn't start feeding the cal til week 4, slight signs of cal/mag def around week 4 but nothing to that degree, with 4 diff strains, at least 6 or 7 diff pheno's.. I mean that could even be heat burned? no ? 75 degrees all the time, what is the max ?

start with a good flush and a root zone conditioner. It looks like hot nutes, gnats, and root damage.

1400 To 1700 ppms? Damn thats hot. They look cooked.