37 days in nute burn? heat stress?

[oks226]

Hey guys,

I'm 37 days into flower and 5 of my 20 plants have developed something wrong. 2 of the 5 affected were watered with nutes yesterday, and worsened over night, so I thought its nutrient burn, but they were watered with weaker nutrients than the previous 2 weeks. The other 3 of the 5 affected havent been watered for 5-6 days, so it also makes me think it is not nutrient burn.

The tips of the new leaves are curling upward, which indicates heat stress, but my room has never been above 84, and that was just yesterday, the rest of the time they are kept between 74-78 degrees, so can they develop heat stress in such low temps?

Here are the pics, see the 2 plants on the right that are affected, they are fed different nutes on different days, but they are in the brightest spot of the room.

and a closer shot of the problem...

 

[Vercingetorix]

When is the last time you flushed? You may consider doing so. You may also want to pull back the lights a little bit and see how they respond. What kinda bulb/wattage are you using and how far away is it from the canopy? Do you have a lumen meter by chance?

 

[Vercingetorix]

Also, what is the humidity in the room? Have you foilared at all recently?

 

[oks226]

I have a lumen meter, but it only goes up to 2000, so its not much help. I did foliar a very little bit, mostly underneath, but a couple sprays up top, just neem oil. I use 1000 watt hps about 18 inches from the canopy, but I have a 8 inch vortex air cooling it, so I can touch the glass and its not hot.

I haven't flushed in about 3 weeks, I did it though today. The House and Garden I am using isn't "suppose to need a flush. Half the plants infected are fed H&G, the other half Botanicare. Humidity goes up to 60% at night and down to 40% when lights on.

I had moved the light up when I first noticed it, but it continued and I have moved the light back down again. I can raise it about 6 more inches and will do so.

Thanks for your help.

 

[Vercingetorix]

There is a possibility the damage is a result of the neem application. It is localized to only a couple plants which may have been sensitive. Did you build the concentration over time? When did you apply the spray, lights on or off? If you did so when they were off, did you do so immediately before the lights came on?

Everything else looks good. If you could keep the humidity at 50 percent at all times, with no fluctuation, that would be ideal.

Also, you can pick up a lumen meter that reads up to 10,000 for only $45 at your local hydro store. I can provide the model if interested. Out of curiusity, what does your lumen meter read now that your lights are pulled way up? (BTW Id suggest returning them to where they were at this point)

 

[Vercingetorix]

What medium are you growing in? I may have one other idea . . .

 

[oks226]

I put the neem on a couple hours before lights out...I didnt build concentration, my mothers showed signs of mites so I quickly sprayed them and then the flower room. I sprayed twice with it, 2 tbsp per gallon and use the green light concentrate neem.

My light meter still reads over 2000 lumens with the light all the way up. I would be interested in an accurate light meter.

Im growing in soil...roots organic.

 

[oks226]

after flush yesterday, plants are still getting worse, the problem is moving down the plant.

Also the plants had an application of neem about 5-6 weeks ago.