Entire sections of plant turned brown while other sections look OK

First year growing Marijuana. Many years of growing vegetables.

My first plant was doing well until I left for a 2 week trip in the middle of September. I returned to see many leaves turning brown. Since there was a big heat wave while I was gone I thought it was just underwatered. Here is a picture from that time:


I watered a lot over the next two weeks but entire sections of the plant turned entirely brown and brittle. Other parts of the plant look totally fine.

Here are photos from today.
Good part of plant:
bad part of plant:

Can someone help identifying the problem? Thanks so much!

Strain; Darkheart Boss OG
Soil in Ground: SLOAT ORGANIC PLANTING MIX mixed with local soil
PH of soil: 6.8
What is strength of nutrient mix? Liquinox Fish Emulsion
Light system, size? Natural sun
Temps; Day,70-100 Night 50-60
Humidity; Not really sure
Ventilation system; Natural wind
AC, None
Co2; No

Since you are flowering it’s rough
I would say remove leaves and have new ones grow but…
I guess remove them anyways to let light in to lower branches. I’d also wait for others who have experience with this to answer

Your pictures wont enlarge for me so I can’t see them well enough to tell you anything. @RedIAm

Try posting only one per post and lets see if that changes anything.

Thanks for the responses. Here are some larger photos.

Plant after heat wave. I thought underwatering did this.

Two weeks later. This is a bad part of the plant. Leaves are totally dead and brittle


Same plant. This section looks totally good. I would think underwatering would kill the entire plant. Is this something else?

Under watering would affect the whole plant. Recovery would start from the bottom up though and it may have been too late. Could also have been baked by the sun while it was underwatered…

Gingerly remove the dead foliage and lets see what we find? @RedIAm

Please tag when responding like I did with your username @bob31 so I get an alert.

Thanks @bob31,

I took off the really bad, brittle leaves. There are still a number of leaves that seem fine in the middle but brown on the edges. The brown is also around other parts of the plant but underneath it seams fine.

Some parts of the plant the brown is at the end of the limb on other parts it is at the base of the limb and the end of the limb is totally fine.

Other parts of the plant are not affected at all.

My experience with other plants leads me to believe that this is a disease, not heat stress or underwatering. Diseases can be localized in portions of plants. Heat stress or underwatering affect the entire plant. I am not expert by any means.

I haven’t figured out when to harvest yet, I am still researching that, but I think I am close. Should I just harvest and hope for the best? Or do you suggest something else.

Thanks again for all your help. This has been a fun journey and I look forward to getting better over time.

My other though was that it got sprayed with something. @RedIAm

I am the sole gardener here so it wasn’t sprayed.

I’ll just harvest it and see how things go. Hopefully next year the same thing will not happen.

Thanks for all your help.