Brown Spots on Camellias

Camellia Scales

• Female camellia scales lay up to 55 eggs when they reach 40 days old. When eggs hatch, young camellia scales, called crawlers, move to fresh foliage to feed off of sap. Scales digest the sap and secrete a sticky residue called honeydew. Infested camellia trees are often covered in honeydew. Furthermore, fungal spores floating in the air attach themselves to the honeydew. The result is a camellia tree covered in a thin black powder referred to as sooty mold.

Damage

• Symptoms of a camellia scale infestation include leaf yellowing on the surface, twig dieback, defoliation, reduced blossom production and death. In addition, camellia trees may be infested with ants. Ants eat honeydew and in return the offer their protection to scales from their natural predators. To treat camellia scale problems, gardeners use a combination of cultural and chemical control methods. The right treatments depends on the severity of the infestation.

Cultural Treatment Methods

• Treat mild to moderate infestations by spraying the camellia to knock off scales and remove honeydew. Gardeners with small camellia trees can pry off some of the scales using a toothpick. Prune off heavily infested leaves using a pair of bypass shears. Remove the infested debris from the area to prevent crawlers from climbing back onto the tree. Furthermore, gardeners can reduce their ant population to allow camellias scale's natural predators to move in. Place ant baits filled with a toxin and attractant around the camellia.

Chemical Treatment Methods

• Spray camellia trees with a refined horticultural oil in the spring to reduce your scale infestation. Horticultural oil kills camellia scales by smothering them. Pick a time after the camellias have finished blooming. Reapply the spray ten days later. Avoid applying horticultural oil to camellias when temperatures are outside 40 to 85 degrees to prevent causing further damage. If horticultural oils fail to suppress the scale population, use an insecticide. Insecticides containing active ingredients such as acephate, cyfluthrin, malathion and carbaryl kill scale insects.