Problem with leaves shrivelling - Mg deficiency?

Been growing a female (Green House Seeds) cheese plant for around 5-6 weeks now and everything seemed to be going fine until last Thursday.

The leaves appear to be yellowing at the tips slightly on some of the older ones and also shrivelling up in the middle and tips.

I have this along with 3 lowryder 2s under a 600W HID, those appear to be fine. Will be conducting a pH test later and will update with the results of those.

Had a look on here and was wondering if it was a Mg deficeincy but if anyone has any suggestions or has had the same problem, I'd be very greatful, thanks.

the tips are curling like a mg def..but there is no spots that would lead me to believe that this is the case..there are just yellowing of the leaves..maybe N def..heres a link that might help until futher intruction.

https://www.rollitup.org/marijuana-plant-problems/164386-problem-leaves-shrivelling-mg-deficiency.html

edit..sry wrong link =p http://www.marijuana-seeds.net/Thanks-ThankYou.htm

here it is..also usually a mg def..will have the new branchs a lime green color

epsom salt will help with mg def..IF IF IF thats the case

Looks to me like she's getting to fucking hot.
Heat stress will cause shit like that, leaves seem to be twisting, discoloured etc.
What are your temps and how close is the light?
What sort of light?

Thanks for the replies guys. Im tempted to lean towards the heat issue. 600W HID which is only around a metre away from the plant. It's a bit of a stealth grow in a cupboard as we're students and probably too strong in reality but was going on ebay cheap. Moved the fan inside the cupboard which Im thinking may have had an impact on the air temperature as it recycles the same air.

I'll see what happens, the lowryders are fine but their much smaller and thus further from the light which may explain that.

I'd agree with the heat. Mg def will have interveinal chlorosis, ur problem seems like its starting at the veins and pushing out, which can be associated with heat stress. The plants look good tho other than that. U should have a thermometer in there and make sure the temps are under 80, No Higher!

feelthevibe said:

600W HID which is only around a metre away from the plant. It's a bit of a stealth grow in a cupboard as we're students and probably too strong in reality but was going on ebay cheap. Moved the fan inside the cupboard which Im thinking may have had an impact on the air temperature as it recycles the same air.

I'll see what happens, the lowryders are fine but their much smaller and thus further from the light which may explain that.

Click to expand...

Yeah, that light, in a cupboard, with little ventilation is gonna cause some heat issues.
Other than having a fan circulating the air in the cupboard, are you exhausting the generated heat out of the cupboard to somewhere via an extraction fan?
As the plants get bigger they're going to need even better ventilation.

those are classic signs of Mg deficiency early stages-seems no one else here picked upt the P deficiency already started and progressing up the plant-see purpling center of leaves and the upper fans tips starting to do ' The P Twist'. I would venture to say you are not feeding enough right now. 600W is alot for these guys too-u r talking 80-100k lumens-close to intensity of the sun. If u r growing in a small cab, u r gonna have issues with this and temps if the cab is not at least 4-5feet high and a fan with at least 100cfm capability. My advice if this is the case would be to save the HID for flowering and buy some CFL's and load em up. That intensity as well cooks that soil leading to an accumulation of fert salt build ups, locking out other available nutes. A good flushing is in order followed immediately by a feeding of 1/2 strength.Good luck.