This Natural Fix for Crape Myrtle Bark Scale Works Better Than Pesticides – And Won’t Harm Bees and Butterflies
Orange oil can attract natural predators to deal with pest populations
Crape myrtles are a common sight in southern landscapes, but they are at risk from an invasive insect in the form of crape myrtle bark scale. There are ways to combat this troublesome pest, but researchers at Auburn University have found a natural method they claim works better than using pesticides.
The team focused on attracting natural predators to deal with the pests. Using orange oil to attract lady beetles, they observed that the beneficial insects significantly reduced the bark scale population within weeks.
Article continues belowWhat Is Crape Myrtle Bark Scale?
Crape myrtle bark scale is an invasive pest from Asia that was first detected in the US in Texas in 2004 and quickly spread across the Southeast. Its primary host is the crape myrtle, but it also targets the American beautyberry, and the pest will affect the look of shrubs and be a reason a crape myrtle is not blooming as well as you’d hope.
Infestations of crape myrtle bark scale can be spotted through black sooty mold on twigs, branches, and the tree’s trunk. The insect is rarer on the foliage, but in extreme cases they may be on the underside of leaves.
Aphids, another common pest of crape myrtles, also cause such black sooty mold, but these insects only feed on leaves. Where the pests congregate is a key way to differentiate between aphids and bark scale.
Heavy infestations of crape myrtle bark scale can cause leaves to yellow and drop, branch dieback, and reduced flowering. Adult females are a few millimeters long and covered with a soft, white, felt-like coating, while nymphs are pinker in color. When the insects are crushed, they excrete a pinkish liquid.
The movement of infected nursery plants has contributed to the spread of the pest. When shopping for new plants to add to your beds or grow crape myrtle in pots, examine plants carefully for any signs to avoid introducing the pest to your area.
Homeowners with crape myrtle can take steps to keep plants pest-free. For example, being too heavy-handed when you prune crape myrtle can leave trees more susceptible, as the pests feed and congregate around pruning wounds.
A Natural Treatment for Crape Myrtle Bark Scale
David Held, professor of entomology and plant pathology at Auburn University, says: ‘Crape myrtles have relatively few pests, but aphids and bark scale are tough ones to shake once you have them.’
The researchers at the university tested biological controls to combat crape myrtle bark scale. Lady beetles are known natural predators that can control it, and the team looked at ways to attract more beneficial lady beetles to help deal with bark scale populations.
They tested scented compounds to discover what attracted the natural predators, and found that orange oil proved the most successful. They tested applying orange oil to infected plants weekly and saw impressive results.
‘We were truly surprised to see this treatment work so well. It worked even better than our systemic insecticides,’ said David. ‘Our students’ work uncovered that these beetles were then able to crush a population of bark scale in just a few weeks, and as a bonus, the orange oil smells great.’
Using natural treatments is preferable to pesticides, which also impact bees, pollinators, and other beneficial insects, as well as the bark scale.
You can use orange oil throughout the season to attract ladybugs to your yard, and also add plants that attract ladybugs for natural pest control, such as nasturtiums, cosmos, dill, and fennel.
Homeowners can get limonene, commonly referred to as orange oil, to use at home. Such as this container of orange oil on Amazon, which you can spray onto shrubs using a spray bottle, like this adjustable plastic spray bottle at Walmart.
How to Control Crape Myrtle Bark Scale
A few small steps can help to keep crape myrtle bark scale at bay. It all starts with planting crepe myrtles in full sun. The shrub wants a sunny spot with at least 6-8 hours of sunlight a day, and studies have shown that crape myrtles in full sun suffer less than those growing in the shade.
Jeremy Pickens, a specialist with Alabama Extension at Auburn University, hails the importance of choosing the right cultivar and planting it in the best spot. ‘Wherever a crape myrtle is planted, full sun is essential. Sun equals flowers,’ he says.
Keeping crape myrtle plants healthy also helps to combat the pest. That includes properly understanding when and how to prune crepe myrtle, so you don’t over-prune and stress the tree.
Fertilizing crape myrtle properly also reduces the risk, as over-fertilizing plants with too much nitrogen encourages tender growth that attracts pests. It is advisable to use a balanced fertilizer in the spring for a level dose of plant nutrients that encourages healthy growth and strong flowering, such as this natural, all-purpose plant food available at Burpee.
Other Ways to Treat Crape Myrtle Bark Scale
There are other treatments or techniques to control crape myrtle bark scale other than spraying plants with insecticide.
These include scrubbing infected branches with a stiff brush and soapy water to impact populations, or pruning out infested branches and destroying them. Any limbs with small populations should be removed to stop the pest from spreading.
Alternatively, plants can be sprayed with insecticidal soap or a homemade bug spray made from two or three tablespoons of liquid soap mixed with a gallon of water. Horticultural soap (you can get ready-to-use horticultural soap at Walmart) works on soft-bodied insects like aphids and mites, but it also comes with a risk to beneficial insects and natural predators.
If you are trying to attract lady beetles to deal with pests, don’t jeapordize things by spraying horticultural soaps at the same time. It is also likely that several applications are needed to deal with infestations, and may not be enough to control large infestations.
FAQs
Will Crape Myrtle Bark Scale Kill the Tree?
Crape myrtle bark scale does not usually kill a tree, but it does weaken the plant and seriously affect its appearance. The invasive pests suck sap and steal nutrients. This stresses the tree, affects flowering, and leaves it more susceptible to pests and diseases.
While larger infestations may kill individual branches, the rest of the tree can survive. If you see an outbreak of crape myrtle bark scale, prompt treatment is advisable to prevent the issues from spreading and killing branches.
What to Shop:
A pack of live adult ladybugs to release into your yard as part of pest management plans. These bugs are predators of many soft-bodied pests, including crape myrtle bark scale.
A lure can be used to attract and keep beneficial predators, such as ladybugs, in your garden. It uses a combination of pheromones and botanicals.
This ready-to-use spray is made with natural orange peel extract (d-Limonene) and is safe to use around children and pets.
If you have a thriving shrub and want more, you can propagate a crape myrtle from softwood cuttings during late spring or early summer. Taking plant cuttings is a way to expand your collection on a budget, but it does require a bit of care and patience.
Take 6-8 inch cuttings from new season’s growth, remove all but the top two sets of leaves, and dip the bottom end into rooting hormone. Place the cutting into small pots filled with a light compost and keep it somewhere in bright, indirect light. It may take six weeks for roots to form.
Love inspiring garden ideas, outdoor advice, and the latest news? Sign up for our newsletter and get the latest features delivered straight to your inbox.
