I have brown spot on my leafs and the but new grow...

Thinking it could be boron deficiency. The first signs of a cannabis boron deficiency is abnormal or thick growth tips along with brown or yellow spotting on new leaves.With a boron deficiency, upper cannabis leaves display abnormal and/or slowed growth. Growing tips may not grow properly, may display twisted growth, and may die off. New leaves may wrinkle or curl. Plant roots can also be affected by a boron deficiency, showing unhealthy or slow growth. Stems may become rough or hollow. Boron deficiencies are more likely to appear when a plant is underwatered or experiencing very low humidity (very dry air). A plant with a boron deficiency may look like it has a calcium deficiency because boron is needed for the plant to properly use calcium. New growth is affected the most, and may look like it’s been burnt or scorched. A boron deficiency is often accompanied by an apparent potassium or nitrogen deficiency, as these nutrients are needed for the plant to use boron.