Very Top Bud Leaves Clawing, Rest of Plant Looks Fine???

[metic]

Hey Riu,

Ive had this happen a couple of times, and never correctly diagnosed what is going on.

This is what my parameters have been lately,

TEMP : 25c-28c
HUMIDITY : 60-70%
LIGHT CYCLE : 12/12
LIGHT CONFIGURATION : 960W mix of high quality cree jb3030 and nichia 757 diodes.
TOTAL SPACE : 4X8
MEDIUM : COCO PREMIUM (plagron)
NUTRIENTS : CANA COCO A+B (usually feed at 1.5-2ml per litre ~650ppm)
CONTAINER SIZE : 3 GALLON FABRIC POT - ROOTS ARE COMPLETELY FILLED OUT
ADDITIVES : NONE AS OF YET (sometimes i will add some liquid fulvic acid )
CULTIVAR : CRITICAL SUPER SILVER HAZE (delicious seeds)
WEEK OF FLOWER : WEEK 7 (day 52)

This is my problem, i have 2 critical super silver haze started from seed, one of which has recently started doing some freaky stuff with her top buds, they looks all clawed over but it only seems to be affecting sites at the very top, and some lower buds look fine.

Bud development is horribly slow, wich leads me to think this may be a nitrogen toxicity, but looking at the leaves they dont seem very dark, Her sister right next to her looks to be starting to get the same symptoms (although she looks a fair bit further along in flower) and is slowly dropping her leaves from the bottom up one by one after they turn yellow...

They were being fed 2 times per lights on cycle, via a water pump and drip tubing at 1 minute per feeding. This usually is perfectly fine for my girls in flower, and i chose to use this cycle as it has always done well. Once i noticed that they were starting to claw i reduced the feeding shedule to 1 feed per light cycle, wich didnt seem to do anything at all, so i then diluted their feed by 50% down to ~300ppm in the hopes they would perk back up. No Signs Of Improvement Yet.

Does anyone know what causes this clawed leaves? they happend to my last crop too and completely ruined about 60% of my girls...

many thanks.

P.S
Sorry for the terrible pics

 

[metic]

I find it weird that only the CSSH are getting claw leaves, and the other 2 strains are loving life and almost finished flower

 

[Sfrigon 1]

Prob from being too close to the light?

 

[metic]

Prob from being too close to the light?

I sort of thought that could be an issue, although they didnt seem to be getting any bleaching so i thought they were fine.

Can too much light cause this?

 

[Sfrigon 1]

I sort of thought that could be an issue, although they didnt seem to be getting any bleaching so i thought they were fine.

Can too much light cause this?

Yes if it feels warm on back of ur hand move em up a little.

 

[hillbill]

Those tops are under some powerful lights. Seems way close.

 

[Hust17]

It’s heat. They’re curling down to try to protect themselves.

 

[metic]

Thanks guys I will try my best to raise the lights and maybe bend the tops over, possibly scrap the whore in a few weeks, when her sister is ready, she is under about 460 watts total, the other half of the area has same wattage but with Cree led strips instead, those girls are doing perfectly fine altho they are heavy indicas

 

[HobbyGrowArtist]

It’s heat. They’re curling down to try to protect themselves.

i had those before, and a kind of bronze glaze. never figured out what it was.

Does anyone know what causes this clawed leaves? they happend to my last crop too and completely ruined about 60% of my girls...

the brown leaf tips that curl up is magnesium deficiency. 28 degrees is a bit high, cannabis plants can tolerate high temperature but they dont require it. could try more ventilation and toss some epsom salt or dolomite into the water.