Are pesky Azalea bark scales attacking your blueberry plants?

The azalea bark scale, Eriococcus azaleas, is a prominent pest of rhododendron, azalea, and huckleberry (Vaccinium spp.).  It has been reported in the Eastern US, as well as Belgium and Russia.  This is a pest that generally does not kill hosts, rather it causes aesthetic damage.  Honeydew can be an inconvenience as well.

How Is It Spread?

  • Eggs are deposited into the white waxy egg sac in late April
  • Crawlers hatch out of eggs in June-July
  • Crawlers prefer branch crotches and twigs where they insert their mouthparts
  • Overwinters as nymph
  • There is one generation per year. (Possibly two in southern states)

Symptoms include:

  • Leaf yellowing is often visible after June or July
  • Sooty mold growing on honeydew can be found under tree or on limbs
  • Branch dieback
  • White waxy threads of the females egg sac near twig crotches prior to June or July
  • Small winged adults males are generally on leaves around August through September
  • Crawlers are reddish, tiny, mobile, and typically found around June or July

We recommend using Organocide 3-in-1 Garden Spray to control azalea bark scale.  Dilute the concentrate version at 3 fl oz per gallon of water and directly spray onto the bark to control the nymphs before they become adults.

Spray the adult scales so Organocide 3-in-1 Garden Spray will slide under their bodies and block their spiracles (breathing holes) causing them to suffocate. It also leaves a micro-film on the plant that will repel egg laying females because they know it’s harmful to their eggs. To break their life cycle, spray once a week for 4 consecutive weeks. If scales appear again in two weeks repeat spraying for another week.