Crapemyrtle Bark Scale in China – – – and in the U.S.?

Given crapemyrtle’s reputation for plant vigor and pest resistance, I was shocked to see Chinese crapemyrtles noticeably affected by a previously obscure pest.  

Last November I had the privilege of traveling to China with Dave Creech (Stephen F. Austin University), Mengmeng Gu (Texas A&M) and Yan Chen (LSU-Hammond). Crapemyrtles, Lagerstroemia spp., are native to Asia, and China is regarded as the first to cultivate crapemyrtle as a flowering tree. As a crapemyrtle enthusiast, I eagerly looked forward to seeing Lagerstroemia collections in Chinese botanical gardens. What we saw in Beijing surprised us.

Figure 1 Note the black sooty mold coating the layers of white and grey scale, believed to be crapemyrtle bark scale, Eriococcus lagerstroemiae. [Photo by Gary Knox in Beijing, China]

Figure 1 Note the black sooty mold coating the layers of white and grey scale, believed to be crapemyrtle bark scale, Eriococcus lagerstroemiae. [Photo by Gary Knox in Beijing, China]

One of the few Asian pests of crapemyrtle is crapemyrtle bark scale, Eriococcus lagerstroemiae. Long considered a minor pest of crapemyrtle, our Chinese hosts indicated this scale recently exploded in numbers, significantly infesting crapemyrtle in some areas. Affected crapemyrtle had greatly reduced vigor and the infestations were just plain ugly (Fig. 1). We did not have an entomologist available to confirm identity of the scale we saw, but our Chinese scientist hosts believed the pest was crapemyrtle bark scale.

Symptoms, Appearance and Distribution in China

An early symptom of crapemyrtle bark scale is black sooty mold covering extensive areas of leaves and stems as a result of honeydew exuded by the scale. Individual scale insects are white to gray in color and ooze pink when crushed (Fig. 2). Large populations build up in branch crotches and extend up branches, appearing crusty white to gray. This scale usually is not present on new growth, leaves or slender stems unless infestations are heavy.

 

 

Figure 2. This white to grey colored scale oozes pink when crushed. [Photo by Gary Knox in Beijing, China]

Figure 2. This white to grey colored scale oozes pink when crushed. [Photo by Gary Knox in Beijing, China]

 

We found this scale on crapemyrtle in all four cities we visited, across hardiness zones roughly equivalent to USDA Cold Hardiness Zones 6b to 9 (Beijing, Zone 6b/7a; Nanjing, Zone 8a/8b; Shanghai, Zone 8b/9a; and Kunming, Zone 9). However, this scale was not found on all crapemyrtle. My personal observation is that stressed plants appeared more susceptible to this scale, as exemplified by infestations on freeze-damaged crapemyrtle in Beijing (Fig. 3) or in a poorly maintained planting in the Nanjing Airport parking lot. Our hosts indicated the problem appeared to be more severe on hybrid cultivars introduced from the U.S., and our observations mostly confirmed that.

In the U.S.?

Unfortunately, crapemyrtle bark scale or a similar scale may already be in the U.S.  A new scale insect believed to be a species of Eriococcus was first discovered in the Dallas, Texas, area in 2010 where it is problematic on landscape crapemyrtles. It has not been definitively identified by entomologists yet and management recommendations are still being developed. However, this scale has since been observed in Shreveport, LA, Memphis, TN, and Little Rock, AR, undoubtedly being moved with plants. The expanding distribution of this scale and my personal observations of crapemyrtle bark scale throughout China suggest this scale could have a widespread and severe impact on crapemyrtles in landscapes.

Figure 3. Dr. Gu is dismayed at seeing this crapemyrtle planting infested by scale (note the black sooty mold on stems). [Photo by Gary Knox in Beijing, China]

Figure 3. Dr. Gu is dismayed at seeing this crapemyrtle planting infested by scale (note the black sooty mold on stems). [Photo by Gary Knox in Beijing, China]

America has a long history of nonnative organisms becoming invasive and causing significant problems in agriculture, landscapes and natural areas (i.e., chestnut blight, Japanese beetle, kudzu, dutch elm disease, granulate ambrosia beetle, laurel wilt, etc.). It is important for all of us to be vigilant in identifying potential invasiveness of organisms, preventing their introduction and spread, and taking actions to minimize or eradicate these invasive organisms before they get “out of hand.” Let’s keep an eye out for this scale and other potential invasives and work together to control or eradicate them.

Preventing Invasive Plants and Animals

Preventing Invasive Plants and Animals

The first week of March every year is designated “National Invasive Species Awareness Week,” an initiative to draw attention to the thousands of invasive plants and animals that move into our state and country every year. However, this is a problem that should draw focus year-round.

Invasive species are non-native or exotic plants and animals which can cause harm to the local economy, human health, and the environment.  They often out-compete native species, causing habitat degradation, wildlife community imbalances, and diseases that can destroy economically important plants. This is a worldwide issue that can be addressed on local levels. In Florida, researchers have documented over 1,180 exotic plant species and more than 500 non-native fish.

Beach vitex is a newly introduced invasive found on our local barrier island due systems.  Photo credit: Rick O'Connor

Beach vitex is a newly introduced invasive found on our local barrier island due systems. Photo credit: Rick O’Connor

Prevention is among the most effective ways to manage invasive species.  Gardeners should be aware of invasive species and make sure they are not unintentionally passing them on to neighbors or natural areas.  While many non-native plant species perform well in our yards and do not become invasive, pay close attention to new plants that start taking over your yard. If you’re unsure of the status of a plant, call your local Extension Office or check the Florida invasive plant list.

When enjoying outdoor activities such as camping, hiking, or biking, be sure to inspect what might have attached to your clothing to prevent further seed dispersion.

Wild hogs cause significant damage to ecosystems throughout Florida.

Wild hogs cause significant damage to ecosystems throughout Florida.

Released pets are a nearly impossible problem to manage, as well.  If you have a pet that you can no longer keep, please find an alternative home for it.  Releasing pets into the wild can have serious implications for native wildlife and cause harm to your animal. One needs look no further than the python problem in the Florida Everglades to see the extent of damage this unwise practice can cause.  Great information on what to do with unwanted pets can be found at Habitattitude.

Among the most important invasive plants to be aware of in our area include: cogongrass, Chinese tallow (popcorn trees), coral ardisia, water hyacinth, Japanese climbing fern, Chinese privet, tropical soda apple, torpedo grass, and beach vitex.  Among invasive animal species in the area, be on the lookout for: lionfish, crazy ants, feral hogs, and Cuban treefrogs.

There are many ways to get involved in the battle against invasive species, including joining your local Cooperative Invasive Species Management Area (CISMA) group. Special thanks to Brooke Saari (bsaari@ufl.edu) for contributing to this article.

Pollinator Protection

Pollinator Protection

 

Landscapes will soon be transitioning from the dormant phase to actively growing and one of the most beneficial insects of all will be back in action.  As soon as flowers open, bees will be visiting to gather pollen and nectar.

This year be a little more observant in the landscape and at your local nursery so that you protect bees during your yard activities.  Several insecticides will have new labels that indicate a toxicity to bees and restrictions about applications to blooming plants.  Since many landscapes have a wide variety of blooming plants, be very careful not to inadvertently spray when bees are visiting open flowers.  Bees are not only killed by a direct spray of certain insecticides, but may carry residual pesticides back to the colony in pollen and nectar.

Since bees and other pollinators are so vital to our food production system, all people who work in landscapes or enjoy gardening as a hobby, need to be a part of bee protection.  Read labels, only spray when absolutely necessary, and learn that a little cosmetic damage is worth it in order to protect pollinators.

Some selections of hollies are one of the first landscape shrubs visited by bees in the winter. Learn about the other plants in your yard that are visited by bees so you are better able to protect them.

Holly flowers will soon open.   Photo:  Beth Bolles, UF IFAS Escambia County Extension

Holly flowers will soon open.
Photo: Beth Bolles, UF IFAS Escambia County Extension

Save Our Citrus!

Save Our Citrus!

sliced citrus fruit

Delicious citrus! Photo by UF IFAS Thomas Wright.

All varieties of citrus – grapefruit, lemon, tangerine, kumquat and orange – are a vital part of our lives here in Florida. We love to grow citrus in our yards so that we can harvest the fruit fresh from the tree. On a wider scale, the citrus industry has a $9 billion annual impact on our economy providing over 76,000 jobs statewide.

 

But there are threats to our dooryard and commercial citrus from pests and disease. Only vigilance will help to combat the challenges so that we may continue to grow and enjoy our beloved citrus trees.

 

What can we do to protect our citrus?
  • Learn about how to properly care for citrus and the pests and diseases that occur.
  • Report any serious diseases like suspected citrus canker or citrus greening to the Division of Plant Industry by calling toll-free 1-888-397-1517.
  • Purchase citrus trees only from registered nurseries – they may cost a little more but they have gone through an extensive process to remain disease and pest free. That will save you $$ in the long run!
  • Don’t bring plants or fruit back into Florida – they may be harboring a pest!
  • Citrus trees or fruit cannot move in or out of the State of Florida without a permit. This applies to homeowners as well as to the industry in order to protect our vital dooryard trees and citrus industry.

 

For more information please see:

Save Our Citrus Website

UF IFAS Gardening Solutions: Citrus

Citrus Culture in the Home Landscape

UF IFAS Extension Online Guide to Citrus Diseases  

Your Florida Dooryard Citrus Guide – Common Pests, Disease and Disorders of Dooryard Citrus

 

 

Oakleaf Hydrangea – A Native Choice

Oakleaf Hydrangeas (Hydrangea quercifolia) make a beautiful choice for the home landscape.  They present great interest in all seasons of  the year.  Not only do they produce beautiful blooms in summer, but the plant also provides great fall color.  When making a choice for a new edition to your landscape, select Oakleaf Hydrangea !

Large Photo of Hydrangea quercifolia

Jeff McMillian @ USDA-NRCS PLANTS Database

Oakleaf Hydrangea is native to Southeastern United States.  I have personally observed hundred of Oakleaf Hydrangeas along streams and on the mountains at the Talledega National Forest in Alabama.  When I saw them they were dormant, as it was February, but it would be a magnificent site when they are all in bloom.

Large Photo of Hydrangea quercifolia

Jeff McMillian @ USDA-NRCS PLANTS Database

Oakleaf Hydrangea blooms are magnificent panicles that change throughout the season.  First creamy white color, turning to a pink and finally desiccating to brown.  There is something attractive about the brown dried bloom and it holds on for quite some time.  In winter, the exfoliating bark make it attractive even though it is without leaves.  This trait, along with the dried out bloom, make it enjoyable throughout the entire year.