How to REALLY control azalea lace bug
Azaleas rank high among the world's most loved plants and few shrubs can beat them when it comes to putting on a spring show.
However, there's a tiny critter that is the bane of gardeners everywhere – the dreaded azalea lace bug! As far as the USA is concerned, this is the worst thing to come out of Japan since Pearl Harbor!
So small is this pest that the human eye can hardly see it without a strong lens. But the damage it does is all too visible. The first thing most gardeners notice is that the leaves on their azaleas have turned a strange, mottled, pale, silvery or bronzy color (though the more observant will have already observed yellow speckles on the leaves) . The surface of each affected leaf looks as if it's been roughed up with sandpaper, while the underleaf becomes speckled with small, dark brown or blackish blobs and develops a rusty look. The whole effect is very ugly and strong infestations affect the health of the plant, leaving it susceptible to fungal diseases resulting in root rot.
So azalea lace bug is not something any gardener can afford to ignore. Yet when it comes to controlling this considerable pest, most advice turns out to be a lot of hooey! So make sure you read on! So-called "organic" and mechanical control methods just don't work with azalea lace bug. I only wish they did, but I've tried them all and without success. Whatever anyone tells you, this is not a problem you can rinse off with a high pressure garden hose, or by using an insecticidal soap. Nor will having healthy, well-fertilized plants prevent a lace bug infestation (though they will of course have a better chance of recovery once treated).
To understand why control is so difficult you need to understand a little about just how azalea lace bug operates. Injury to the host plant is caused by the adults and nymphs (baby lace bugs) feeding on the foliage by first piercing and then sucking to extract the liquid contents of the leaf tissue through the under surface. Damage usually begins on the lower leaves and moves upward.
So it takes a pretty powerful systemic chemical to prevent early infestation or quickly get rid of any existing infestation; one that is able to remain in the plant's "system" for some time to deter reinfestation.
By far the most effective method to date is Bayer Advanced Garden, Tree and Shrub Insect Control, marketed in some countries under the name of Confidor. This "new generation" systemic insecticide has proved reasonably benign in the environment so far, especially compared with the poisons of yesteryear. And no, this is NOT an advertisement because in general I advise against the use of pesticides in the home garden. It's just that I grow a lot of azaleas, and advise many other people who grow azaleas, and we need a control method that really works.
Still, it IS a chemical solution so those who won't have any chemicals in their gardens will have to seek other remedies. Insecticidal soap and Neem Oil offer some control but are not nearly so effective as the Bayer product. In any case, though they are considered more environmentally friendly, these products ARE still chemical in nature. As are most "organic" garden solutions. So, really, those who are not prepared to spray, shouldn't grow azaleas!
The secret of keeping your azaleas lace bug-free is to be prepared and commence a regular annual spraying regime. Where azalea lace bug is known to be a problem, the best control program is to spray azaleas in mid spring, when the first sign is likely to appear. Spraying needs to be very thorough, using a fine nozzle and being sure to spray the under leaves. I find that Advanced Garden, Tree and Shrub Insect Control will keep the bugs at bay until the following spring, if used promptly and thoroughly. Though in some years, where weather conditions favour severe lace bug infestations, a second spraying in autumn might be necessary.
For those, like myself, who hate using chemicals in the home garden, there is some hope on the horizon when it comes to controlling azalea lace bug. Bug resistance can be bred into the host plants and some breeders have been doing this, with several of the Encore range of autumn-flowering azaleas showing encouraging signs of lace bug resistance. Also, beneficial predators may be found which will gobble up the lace bugs in your garden while leaving other, non-harmful insects alone. Research into this is already well underway.
So maybe in the future we won't have to spray our azaleas at all – a good thing because the history of horticulture shows that insects are cunning critters and soon develop a resistance to most chemicals. In the meantime, I recommend a strict control regime, a shady position for your plants (because lace bugs appear to thrive in sunlight) and good growing practices so that your azaleas have a better chance of recovery once an infestation has been identified and treated.
About the Author
Julie Lake is a horticulturist and gardening writer with many years experience in creating great gardens and helping other people to do so. She is founder of the GardenEzi easy gardening concept and the author of many gardening books including the GardenEzi five-step program series Growing Great Azaleas, Gardening in a Hot Climate - Tropics and Subtropics, Tropical Foliage Gardening and the revolutionary How to Have a Great Garden for Just Two Hours a Week.
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