Is this what PK burn is? or lack of?

[geralds]

Hey guys,

I just entered into week 6 of a 10 week stardawg strain. I've been giving them light doses of pk 13/14 since week 5( 2 ml per gallon)
for the past couple days I've been adding about 2.5-3ml per gallon with a overall EC of about 1.3-1.4. I've noticed some of the smaller leaves coming out of the top of the bud are starting to turn yellow. it is however the buds closest to the light from what it looks like. I'm running 4 1000w DE with 1200ppm of c02.
5 gallon fabric pots, and feeding only Canna coco line nutrients. Does this appear to be from the PK? or a deficiency of something? or light? if its the light that would be odd because they've been under this light for over a month with no big issues. Any advice would be great.

Thanks

 

[Kampbe1l]

my first thought was maybe heat...the curled up edges of the leaves (?).

slight yellowing of the leaves near the edges and the curl of the leaf could be also symptoms of a potassium issue,

but then, the end-product does looks like this...

 

[MIMedGrower]

Too much pk causes early yellowing and burned edges like you show. I would run fresh water through to get the ec down then feed a lower strength complete balanced grow ratio nute to get things back in balance.

 

[Jimster]

Usually the canoe'd edges suggest too much heat, but they don't appear to be close enough for that to be an issue. It could also be a P/K imbalance or overdosage, as this can cause a lot of symptoms secondary to the overage itself. I agree that a flush wouldn't hurt anything, but be sure to give a little bit of nitrogen afterwards to keep the plants from prematurely drawing nutrients out of the bottom fan leaves.
Look for hot spots under the lights... sometimes they tend to concentrate light in certain areas. The damage DOES look more heat related, especially with the topmost (closest) buds being affected most. Have you checked the temps at bud level? IMO, if not heat related, then it is too much nutrients.

 

[02trueblue]

I'd lean towards overfeeding... like stated above a flush couldn't hurt and you can give them a little boost after you flush out the old nutes

If it was a deficiency, there would be more yellowing and the undergrowth would be affected more. IMO

 

[Kevuk]

That is def pk burn.