Ya got great internodal growth going on! This has potential for a huge harvest, and that stem looks exactly how you want. You have a huge vascular system pulling nutes to the buds.
Like BDK said, you're going to want to keep an eye on your airflow, and its smart to keep your humidity lower to help prevent problems. I wouldn't however advise defoliation for autos, their lifespan is so short any stress will set back the final product, as it takes time to recover. Best to keep on the track youre taking (a la Humboldt Local) and keep it unstressed. It's working great for you so far!
Are you using anything besides the Advanced Nutrients you listed? What's your reasoning behind nutrient ratios? What's your light source? And is that a fabric grow bag, like a smart pot?
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