Yesterday morning, official pre-dawn temp went down to 45°F. When I went to check on the luffah on the neighbor's side of the fence, there were a whole bunch of leaves that had blackened -- they looked like they had been hit by frost. Here is a photo I took after removing all the blackened and worst of the yellowed/browned leaves.
But after looking at the photo and noting the lush green lawn all the way up to the bottom of the fence, I'm wondering if their lawn service had been randomly spraying again even though I have asked a number of times to hold their sprayer wand CLOSE to the ground when they are spraying along the fence.
One young man actually said the wand "doesn't reach" as he stood upright and held the handle at his waist level....
Well, that's part of the reason for growing a fairly solid growth, non-critical crops along this fence -- to catch the stray air-borne spray particles so they don't make their way past the gaps in the fence. So I decided I wasn't going to try eating any of the immature luffah fruits on this side of the fence. There are two really big fruits and one medium fruit on this side that I hope will continue to grow for a little while longer to harvest for sponges and seeds (I suspect the luffah vines are probably benefitting from their lawn fertilizer

)
If I wasn't eating them, what to do with the not quite mature luffah.... then I came across instructions for processing luffah that are still green yet sufficiently matured for sponges but not for seeds.
(This one is in Japanese -- use Chrome or other browser that will translate for you if you need the words, but the pictures explain most of the process.) Most of this type of instructions say to boil for few minutes to 20 minutes until the thick skin and flesh come off easily. Obviously boiling would kill the seeds even if any of them are mature enough to grow. But usually, the seeds shown are white and immature like these.
https://mango.main.jp/kurasihetima1.html
I tried with my immature fruits and one not quite mature medium-large fruit (previously harvested or fallen). Most of them were completely useless for sponges as I suspected but produced some soft fibers. don't know if there are any use for them, but I'm drying them.
Apparently, you can get softer, not as coarse sponges from not quite completely mature fruits which some people say are better for skin care than the rough, hard fibers of the fully mature fruits which are better relegated to kitchen and other scrubbing/cleaning duty. "Starting to yellow" seem to be the key level of maturity -- my one almost mature fruit that yielded those sponges still had the really soft fibers near the stem end.