Causes

• A number of factors contribute to brown leaves on potted avocado plants. The root systems of avocado trees act as a series of tubes that take in water and nutrients for the rest of the tree. Avocado trees that don't receive enough water will become dehydrated, turning the leaves brown. Too much water suffocates the roots, which will also turn the leaves brown. Fertilize avocado trees annually so the potting soil has nutrients for the trees.
  
  

Pests and Diseases

• Problems with pests and diseases also affect the health of potted avocado trees. Aphids are a serious problem for potted avocado trees growing indoors and outside. Aphids feed on the leaves of avocado plants, leaving wounds and often becoming a source of disease as well as leaf damage that causes the leaves to turn brown. The diseases spread by aphids can include root rot and other fungal diseases that turn the leaves of avocado trees brown.
  
  

Cultural Control

• Keeping the avocado's growing environment healthy is one key way to avoid browning leaves. Failure to give a potted avocado tree the right conditions for growth results in brown leaves. Water the avocado tree at least once a week to keep the soil moist several inches into the planter. Remove any fallen leaves from the soil of the planter to avoid disease. Remove any dead or diseased limbs.
  
  

Pesticides

• Pesticides are chemical controls for potted avocado trees that help limit the damage pests can do to the tree. Spraying a potted avocado tree with pesticides kills off the larvae of pests and helps the tree fight off the adult insects, preventing them from feeding on the leaves of the tree. Follow the schedule recommended on the pesticide label for best results.