Bugs

• Scales, red mites and leaf miners attack holly bushes, but don't usually cause much damage, and spraying insecticidal soap on them easily controls them. Red mites are tiny reddish brown bugs that feed on the undersides of leaves. Since they only grow about 1/50 inch long and are hard to see, it's easier to look for the webbing they produce. Symptoms of red mites include the appearance of light yellow dots on leaves. Leaves may also turn a bronze color and fall off the bush. Leafminers are the larvae of small flies that tunnel through the leaves. Their tunnels turn yellowish brown, and leaves may look deformed from the puncture wounds the adult fly makes when laying eggs. Scales are small, round or oval insects with no visible legs. They look like small brown or gray bumps on the bottoms of leaves, and they damage holly by feeding on the sap in the leaves.
  
  

Holly Spot

• Holly leaf spot or holly tar spot is a serious fungal disease that can cause your plant to become defoliated. Symptoms include the appearance of black, yellow or brown spots on the leaves. Leaves start falling off the plant starting at the bottom and moving up. To prevent leaf spot, prune bushes so they receive sunlight and good circulation of air. Don't water plants in the morning or at night. Fungicides can be applied during early stages of the disease, white the spots are still yellow. Once leaves start to fall not much can be done to stop it, but holly leaf spot doesn't kill bushes, and they will grow new leaves. To prevent a return of the disease, remove infected leaves from your bush, clean up fallen leaves and destroy them.
  
  

Cankers

• Botryosphaeria, or bot cankers, affect yellow-berried hollies. Cankers don't usually damage healthy plants, but plants suffering from exposure to very high or low temperatures, or to drought conditions, are susceptible to them. Symptoms include the appearance of cankers, which are shrunken, cracked areas of dead bark, on the branches and twigs. If branches become completely encircled by cankers, the leaves on those branches may yellow and drop. Twigs die back, and tissue surrounding the canker turns brown. Prevent cankers by ensuring that holly bushes are planted in good draining soil, with the root ball slightly above or even with the soil level. Mulch to retain moisture and to protect hollies from injuries caused by mowers and weed trimmers. Make sure the pH is between 5.0 and 6.0.
  
  

Other

• Other diseases that attack hollies include Cylindrocladium leaf spot and anthracnose. Both of these diseases are fungal infections. Symptoms of Cylindrocladium leaf spot include small yellow spots that grow bigger and develop tan centers and purplish black borders. Symptoms of anthracnose include the appearance of tan or brown blotches on the leaves. Many pinkish-orange spore masses appear inside the blotches when it's humid. Fungicides can be used to control both of these diseases.