How do I correct boron deficiency in cauliflower with brown curds and hollow stem?

Brown curds, a bitter taste, and a hollow browned stem in cauliflower are the classic signs of boron deficiency. Boron is needed for cell wall strength and for the growing points, so when it is short you also see brittle, distorted young leaves, cracked stems, and a corky brown discolouration inside. Boron is immobile, so symptoms hit the new growth and the developing curd. It is common on sandy soils, high pH soils, and after heavy liming or in dry spells. Please confirm with a soil test or your Soil Health Card before applying, because boron has a very narrow safe range and the deficiency can also be confused with other curd disorders. The usual correction is borax (sodium borate). A soil application is commonly in a small range like roughly 4 to 8 kg borax per acre mixed well and applied at planting on confirmed deficient soils, and a foliar spray of around 0.1 to 0.2 percent borax can rescue a standing crop. The most important caution with boron is that the gap between too little and toxic is very small, so weigh it accurately, mix it evenly, and do not over-apply. Follow your soil test and local KVK recommendation exactly.