Hi Vinoy,

Dracaena compacta plants usually get black leaves and tips from too much water or too much chlorine in the water. Automatically watering once a week is a bad idea. You need to check the soil and not water until it has practically dried out. Thee plants like to be on the dry side. Depending upon the temperature and humidity in your home, your dracaena may not need water for two weeks or more. Sadly, it sounds like one of the stalks has died already from over-watering. If your household water has a lot of chlorine or fluoride in it, allow it to sit out over night before using it. To much plant food is another cause of black leaf tips. Always dilute your plant food to 1/2 the recommended strength and only feed a dracaena monthly in the spring and summer and never in the fall. You can read more about draceanas in the Popular Houseplant section of the website.

http://www.houseplant411.com/houseplant/dracaena-compacta-how-to-grow-care

Dracaena compacta plants are considered  to be slightly poisonousPlants are a great addition to homes and offices, but it’s important to know whether your plants are dangerous to children, pets, or even adults. Some plants contain chemicals such as oxalates, solanine, glycosides, or alkaloid lycorine that may cause vomiting, nausea, diarrhea, swelling and redness of the mouth, throat, and lips, and trouble breathing. Touching parts of certain plants, especially the sap, may cause various skin irritations. The weight and age of the human or pet involved, and the part and amount of plant eaten determine how severe the reaction to the toxins will be. Although plants may be listed as non-toxic, they can still cause individual allergic reactions. If there is any question after a houseplant has been ingested or touched immediately call the Poison Control Center 1-800-222-1222 The Handbook of Poisonous and Injurious Plants [Paperback]is an excellent reference to keep around if you have young children and pets., especially to dogs and cats. Read more about common houseplants that are poisonousPlants are a great addition to homes and offices, but it’s important to know whether your plants are dangerous to children, pets, or even adults. Some plants contain chemicals such as oxalates, solanine, glycosides, or alkaloid lycorine that may cause vomiting, nausea, diarrhea, swelling and redness of the mouth, throat, and lips, and trouble breathing. Touching parts of certain plants, especially the sap, may cause various skin irritations. The weight and age of the human or pet involved, and the part and amount of plant eaten determine how severe the reaction to the toxins will be. Although plants may be listed as non-toxic, they can still cause individual allergic reactions. If there is any question after a houseplant has been ingested or touched immediately call the Poison Control Center 1-800-222-1222 The Handbook of Poisonous and Injurious Plants [Paperback]is an excellent reference to keep around if you have young children and pets. in Don’t Feed Me To Your Cat! A Guide to Poisonous Houseplants