Base of stems shrunk what to do?

Hi all,

I have a couple of NFT tables with vert lights down the middle

I am in trouble as it would seem I have stem rott and not sure what to do. The very bottom of the stems for about 1 - 2 cms have reduced in size by up to 50%
....it is so bad some of them have fallen over and ive had to strenghen them with garden twine

Both the tables are completely covered with lightproof plastic and well sealed they are covered in such a way little or no air can get in. the blocks are totally soaked

This morning I have changed the NFT pumps so they come on 15mins every 6 hours (they were on 24/7) and pulled back the cover off the ends of the tables to get some air at the roots..the problem is something to do with this I reckon as no air was getting to the roots on the spreader matts and cubes due to being clipped down so tight...

The roots are a perfect white colour and are out and all over the spreader matts

PH 5.8
EC 1.0
3ml per litre of Rhizotonic
0.5ml per litre of Oxygen h2o2
Room temp 26 degrees centigrade
Room humidity 40%
Water temp 21 degrees

Anyone ever seen this?...the weard thing is they are still growing at a good normal rate

Basically the same as damping off. If you can correct the moisture and oxygen issues they MIGHT survive. Prop them up for now if needed.

hotrodharley said:

Basically the same as damping off. If you can correct the moisture and oxygen issues they MIGHT survive. Prop them up for now if needed.

Click to expand...

so its a bacterial infection? Its normal just for the very bottoms of the stems to rott like that?

Damping off is usually caused by the water/solution levels being too high. It's common in seedlings where people keep the peat plug or rockwool cube too wet. It isn't bacterial but mechanical. Dropping the water level and propping them up might allow the stem to strengthen and the plant to live.

hotrodharley said:

Damping off is usually caused by the water/solution levels being too high. It's common in seedlings where people keep the peat plug or rockwool cube too wet. It isn't bacterial but mechanical. Dropping the water level and propping them up might allow the stem to strengthen and the plant to live.

Click to expand...

going to feed them once a day for 15minutes

ive opened the end of the nft cover so air can get inside easier

Also going to add some h202 to the reservoirs and soak some in cotton wool balls and wrap it round the effected stems

Can I take cuts off then? then destroy them?

Just had a proper look at them...

Theres 17 in total and can safely say at the moment 5 have no chance

The other 12 have the beaver ring round them just above the cube but below the ring the stem is the same size and a healthy green colour like above...However when I push the root riot apart a big the stem thats inside is a healthy green colour but with whiteish dimples on it?

Either way im fucked as I cant go throwing the other 27 in there and the same thing happens to them so it looks like a kill and properly clean job then replace the fucked 17 with new seedlings.

Need to establish what the cause of this was though. I put a proper thermometer in the water earlier and its 28 degrees!...the plastic on top is sort of acting like an oven so ive moved the lights up about another foot

The rockwool cubes are so wet they are almost falling apart...I think its a combination of heat, massive overwatering and lack of ventilation due to the plastic sheet being pulled over the whole system and clipped down with 20+ fold back stationary clips so theres no where the air can get into the roots...I have now folded the end back however so air can get in

Hi all...Someone on another forum had his first 4 grows wiped out with this same stem rott he was using NFT and seedlings also.

He experimented with various watering techniques etc of which made no difference until he lowered his EC right down then built it up slowly with the water on 24/7 and the blocks straight on the spreader matt then he had success...he did this because he noticed it didnt happen if he put the established blocks straight on in ph'd water. So in my case my EC was 1.2 so they had gone from EC 0.4 (EC of plain tap water) to 1.2. Do you think its possible this is the reason? Perhaps its strain dependant? I allways thought if you over nute them the first thing that happens is you get tip burn etc?

I also had Oxygen h202 at 60ml per 100 litres in the mix........

Tonight I am going to try hitting the blocks with a grow EC of 0.8 (they have only had ph'd water so far and the roots are well out of the blocks now) and leave them in the propogation tent?.......

soak some in cotton wool balls and wrap it round the effected stems

Click to expand...

Your trying to keep the stem bases as dry as possible so dont do that. Stop spraying the plants, can you also take some plastic away from the cubes so they can dry quicker? as its the rw cubes staying too wet for too long that has caused this. Fan s/b blowing on them 24/7.

ripped them all out and gave everything a damn good scrubbing in h202 today and have double rinsed everything...all the cleaning materials (towels, scrubbers, buckets etc) were bagged up and binned also

I have 12 in 3" cubes that are bursting out the bottoms...I gave them a 0.8 EC feed of grow yesterday and today they have gone wild
These 12 are currently in the propogation tent with a T5 above them sitting on a tray

Today I got some tile spacers and stabbed one into each corner of the bottom of the cubes avoiding damage to the roots as much as I could. An hour ago me mate phoned me to say now that the tile spacers are in and the blocks are off the floor of the tray by a cm or so the roots have started to hang down and touch the tray of which is bone dry.

I also put tile spacers in the bottom of 15 more 3" cubes of which I put the smaller rooted cubes into yesterday so they are not out the bottom of the 3" cubes yet

I am trying to get the roots to hang off the bottom before I put them on the nft's.

Should I put some water with a 0.8 EC in the bottom of the trays?...the propogation tent air temp is 28 degrees C which would mean this water would be at 28 degrees pretty quick I reckon...im asuming the roots would try and sit in this water? Im not sure if just leaving them to dangle dry for 2 days would make a difference?
Thanks