Answer: I think you have a Dieffenbachia. There are many different possible causes for browning. This is a tropical plant that needs indirect light, high humidity and evenly moist soil. This means damp like a wrung out sponge, not sopping wet/saturated and never dried out. If over or underwatered, it will turn brown. Overwatering usually causes browning beginning at the base first, underwatering usually causes drying at the leaf tips and top of the plant first. If there is a saucer under the pot, empty it after watering. Make sure the drainage holes in the pot are open and working.
In too much light or direct sun, it will sunburn and turn brown. Light should be indirect.
It can be fertilized with a water soluble fertilizer for foliage plants from spring to fall, use the weaker strength on the label. Overfertilizing will make it turn brown, beginning at the edges of the leaves. Underfeeding can cause it to yellow all over.
Do not use water from a water sofener, the salts will damage the plant.
This plant is sometimes subject to insect problems. You might find spider mites and their fine webbing along the undersides of the leaves and along the stem; treat these with commercially formulated insecticidal soap per the label directions, be sure to cover all parts of the plant from top to bottom and undersides of the leaves with the spray. Rinsing the plant with plain tepid water once a week and increasing ambient humidity will also help slow these down.
You might see mealy bugs which look like small bits of white fluff, usually at the joints where leaves come off the stem and often accompanied by a stickiness on the foliage; treat these with insecticidal soap and/or dab them with a cotton swab dipped in rubbing alcohol.
I hope this helps you trouble shoot.
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