Question: query regarding management of stem rot in betelvine. 
Answer: --spray copper oxychlioride (blitox-50,blue copper) 3 gram/liter of water 3 times at 5 days interval in the evening time  or you can spray 2% bordeaux mixture (100gram tutia or cuso4 in 5 liter of water and 100 gram lime powder or caco3 in 5 liter of water) 3 times at 5 days interval in the evening time.