Azalea lace bug infestation.

Asked June 7, 2018, 10:38 PM EDT

My standard azalea has a heavy infestation of lace bug and is now dropping leaves. It has a large canopy, so should I prune and then start spraying with a premixed spray. I live in Victoria Australia and just heading into winter, but the plant is protected from the elements. I would appreciate your help as I have had it for many years and would hate to lose it. Cheers, Lorraine.

Outside United States

1 Response

Thanks for contacting us. I am not personally familiar with this pest. However, Ask an Expert has responded to a similar inquiry in the past. Here is the response:

There are two problems with this bug's control in our gardens. First, there are as many as 4 generations each spring/summer, so spraying has to occur at the exact time that the nymphs (the stage after being eggs) hatch. Second, since the eggs are laid on the underside of the leaves, in order for a spray to be effective, it needs to land there, not on the top of the leaf.

This question was posted last year on Ask an Expert, and the expert's answer was thorough and clear, so I think, rather than repeat it, I'
ll provide this link to it:
https://ask.extension.org/questions/304777

As the answer indicates, it is probably now too late in the season to treat the most current generation, but you can examine the undersides of the leaves to see if there are any nymphs feeding there now. If you find eggs (which will overwinter there), hitting them with a strong stream of water may dislodge them from the surface, so they're not there in the spring to start the process all over again.

Here is some additional information which may help you:
https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/azalea-rhododendron-azal...