Never seen this before? Pics included

One of the tops on my 818 headband has got its sugar leaves becoming necrotic and going brown 7 weeks into flower. Only one top is affected and the pistils are browner than the rest. My PH is fine and have only been feeding with 1/4 dose biobizz grow in biobizz soil so I doubt its nute burn?
Temps were up to 27-31 Celsius this week due to local heatwave but that's all I can think off.

Affected bud
an example of the other unaffected buds
whole plant

I will guess some form of mold or bud rot. Try to get a look deeper inside that affected bud and see what is going on. You might want to cut a clove off near some of the browning to see the interior.

Bugeye said:

I will guess some form of mold or bud rot. Try to get a look deeper inside that affected bud and see what is going on. You might want to cut a clove off near some of the browning to see the interior.

Click to expand...

Ive opened it right up and theirs no discolouration on or right in the bud, its just the leaves affected. I might just chop that top and stick it in the oil pile incase its contagious whatever it is ha!
Cheers for the quick response bugeye!