Indoor Houseplant Diseases  

Indoor houseplant diseases are causes by three primary organisms; namely, fungi, bacteria, and viruses. It is very important that you keep your plants healthy in order to prevent the conditions which foster the growth of these destructive organisms.

Fungi thrive in damp conditions and cause a variety of plant ailments such as:  Root and stem rot which occurs when roots, and stems become soft, turn black and die.

This problem is caused by overwatering and poor soil drainage.

If the problem is not too severe, repotting the plant in sterilized potting mixture may save it.

Leaf spots may appear on leaves as large black discolored areas where the plant leaves wither and die. This condition is greatest during wet weather and high humidity. Remove damage leaves and destroy. Then treat with appropriate fungicide.

Mildews come in the form of powdery mildew which covers foliage with a white powdery coating. This is caused by overcrowded plants in humid, shady locations.

Downey mildew appears as dark spots on upper leaf surface and gray mold on the lower leaf surface. This condition is prevalent in wet weather. Spray powdery mildew with sulfur and spray downy mildew with ferbam or zineb.

Botrytis blight is also know as gray mold.  It affects the buds, flowers,  and leaves of many indoor plants.

  • To avoid this problem, keep leaves dry and provide good air circulation.  
  • Add a fan to the area where you keep your plants. The circulating air will decrease the humidity surrounding the container and help the  top layer of soil dry out better.
  • Use a vinegar solution to increase your plant's soil pH, making it more acidic and less hospitable to mold.

Bacteria and Viruses Attack Injured Plants

Viruses are spread by sucking insects such as aphids. Plants are affected when left outdoors. Growth is stunted, the leaves are yellowed and streaked, and the foliage is deformed. There is no effective treatment. Destroy infected plant and sterilize any tools used with rubbing alcohol.

Preventive Plant Medicine

It is vital that you practice preventive plant medicine to make your plants resistant to pests and indoor houseplant diseases by doing the following:

1. Always remove dead leaves and tips when they turn brown to prevent infection.

2. Use only sterilized, well-aerated potting mixtures.

3. Water carefully to keep water off foliage because fungus spores need water to germinate and bacteria spreads from plant to plant in splashing water.

4. Provide plants with adequate light to manufacture food for growth.

5. Thin out bushy plants to allow air circulation around plants to reduce infections.

6. Monitor your plants continuously for any abnormalities and isolate any suspicious plants.

Regularly grooming houseplants is the key to to preventing indoor houseplant diseases for healthy and attractive plants.