The heads of the Sunflowers are becoming heavy, and with the extra weight they are all facing downwards towards the ground. Most are already about 1ft in diameter, and they are full of seeds.
The male plants have now been removed, and the female seeds are almost ready for harvesting. They will then be stored, and sold for sowing next year; maybe some will grow near you.
The male plants represent about a 10th of the crop, and are essential for fertilising the female plants, but at this time of year they are all destroyed. I still fail to see why the seeds are not harvested separately; the females for seed, and the males for oil. It does seem that by destroying all the male heads, they are not taking full advantage of the crop. Parrot food even!
The male plants are in separate rows so they can be easily destroyed (below). As male seeds are needed, I imagine there are other farmers elsewhere who specialise in growing the male seeds. Perhaps someone could enlighten me!
The plants will soon be 'treated' to make them die-off, then the combine-harvesters will come in to shake all the seeds out.
Soon the Chestnuts will be ready to be harvested, and it'll be another growing year over.