• Pests, improper care and diseases may diminish holly tree production.Jupiterimages/Photos.com/Getty Images
  
  Holly shrubs are known for their festive red berries and distinctive leaves. According to the University of Arkansas Cooperative Extension, over 20 species of holly are native to the United States, and there are over 300 species worldwide. Problems with holly shrubs may be related to pests, disease or improper care.
  
  

Yellow Lesions on Leaves

• Yellow spots on holly shrub leaves may be related to a variety of pests or diseases. Phytophthora root rot causes leaves to turn yellow, usually around the shoot tips. It also results in leaf drop and decreased plant growth. If you notice small, light yellow spots on leaves, you might be dealing with the southern red mite. These pests may also cover leaves and branches in webs. Yellow, tunnel-like patterns on leaves are most likely caused by leafminers, which live inside the leaf tissue and also cause small holes in leaves. Yellowing of leaves can also be caused by under-watering.
  
  

Black or Brown Roots

• Holly shrubs are susceptible to black root rot, which is a fungal infection that primarily affects plant roots. Roots turn black or brown, starting at the tip. Other symptoms of black root rot include overall decline, increased sensitivity to drought and stunted growth. The fungus flourishes in cold, wet soil conditions and can remain in the soil for several years. Some holly species, such as Chinese and English holly, are resistant to black root rot and should be used in planting sites that have had previous growth.
  
  

General Decline

• If your holly shrub seems to be declining without any specific additional symptoms, the problem could be related to watering and other planting conditions. Most holly varieties require well-drained, slightly acidic soil and full sun. In the winter, some types of holly shrubs may decline and leaves may turn brown. Drought is another common culprit of general plant decline. Adjust watering frequency and consider amending your soil with organic matter to bring your holly shrub back to its full potential.