Why are the Azaleas “Bleaching Out”?

Why are the Azaleas “Bleaching Out”?

Leaf with color fading

Damage caused by azalea lace bug, Stephanitis pyrioides (Scott), feeding. Photograph by James. L. Castner, University of Florida. Severely damaged leaves become heavily discolored and eventually dry or fall off. Symptoms may sometimes be confused with mite injury, but the presence of black varnish-like excrement, frequently with cast skins attached, suggest lace bug damage (Johnson and Lyon 1991).

You may be noticing the color disappearing from your azaleas right now. Do your azaleas look bleached out from a piercing-sucking insect. The culprit is probably azalea lace bug, Stephanitis pyrioides. This pest overwinters in eggs on the underside of infested leaves. Eggs hatch in late March and early April. The insect then passes through five nymphal instars before becoming an adult. It takes approximately one month for the insect to complete development from egg to adult and there are at least four generations per year. Valuable plants that are susceptible to lace bug damage should be inspected in the early spring for the presence of overwintering lace bug adults, eggs and newly-hatched nymphs. Inspect these plants every two weeks during the growing season for developing lace bug infestations.

Both adults and nymphs have piercing-sucking mouthparts and remove sap as they feed from the underside of the leaf. Lace bug damage to foliage detracts greatly from the plant’s beauty, reduces the plant’s ability to produce food, decreases plant vigor and causes the plant to be more susceptible to damage by other insects, diseases or unfavorable weather conditions. The azalea can become almost silver or bleached in appearance from the feeding lace bug damage.

However, lace bugs often go undetected until the infested plants show severe damage sometime into the summer. By then several generations of lace bugs have been weakening the plant. Inspecting early in the spring and simply washing them off the underside of the leaves can help to avoid damage later and the need for pesticides.

Adult lace bugs are flattened and rectangular in shape measuring 1/8 to 1/4 inch long. The area behind the head and the wing covers form a broadened, lace-like body covering. The wings are light amber to transparent in color. Lace bugs leave behind spiny black spots of frass (excrement).

Insect with clear wings.

Adult azalea lace bug, Stephanitis pyrioides (Scott), and excrement. Photograph by James. L. Castner, University of Florida.

Lace bug nymphs are flat and oval in shape with spines projecting from their bodies in all directions. A lace bug nymph goes through five growth stages (instars) before becoming an adult. At each stage the nymph sheds its skin (molts) and these old skins often remain attached to the lower surface of infested leaves.

Small dark-colored insect on leaf with shiny black spots.

Nymphs of the azalea lace bug, Stephanitis pyrioides (Scott), with several cast skins and excrement. Photograph by James. L. Castner, University of Florida.

Azalea lace bug eggs are football-shaped and are transparent to cream colored. Lace bug eggs are found on the lower leaf surface, usually alongside or inserted into a leaf vein. Adult females secrete a varnish-like substance over the eggs that hardens into a scab-like protective covering.

Other plant species, such as lantana and sycamore, may have similar symptoms. But, realize that lace bugs are host specific. They feed on their favorite plant and won’t go to another plant species. However, the life cycle is similar. Be sure to clean up all the damaged leaves. That’s where the eggs will remain for the winter. Start next spring egg-free.

For more information go to: http://entomology.ifas.ufl.edu/creatures/orn/shrubs/azalea_lace_bug.htm

Natural Walls

Natural Walls

Everyone likes their privacy. Usually, a large eight-foot privacy fence is built for that reason. That option tends to be expensive. What is a different approach for a similar result? A natural wall!

One advantage of having a natural wall is that a homeowner has options when choosing plants. When it comes to choosing plants for a natural wall, the first thing to decide is if a wall needs to be year round or seasonal. Size would be the next factor to determine.

Japanese Cedar (Cryptomeria japonica) has the capability of growing 40 to 60 feet in height and 15 to 20 feet in width. There are some smaller varieties to pick from, but where is the fun in having a small wall?

Another plant option that would require pruning, but make an excellent natural wall is Japanese Yew (Podocarpus macrophyllus). This specimen will grow 30 to 40 feet tall and 20 to 25 feet in width if left unpruned, however, it is a slow grower. Yaupon Holly (Ilex vomitoria) comes in several selections of various sizes so the height range is 3 to 20 feet. The width range is 5 to 15 feet.

The Emerald Green Arborvitae is a fast grower that would be ideal for the homeowner who does not want a tall wall. It keeps a tight pyramid shape that will reach heights up 12 to 14 feet and needs 4 to 6 feet of space. Green Giant Arborvitae or Thuja Giant (Thuja standishii x plicata ‘Gre) is an excellent tree to pick for a natural wall. It has the capability to reach 50 to 60 feet in height and spreads out 12 to 20 feet at maturity. This arborvitae is considered to be a fast grower since it can increase more than 24” per year.

The larger selections of Loropetalum are other shrubs that homeowners have used to establish their privacy wall. One can expect a height up to 15 feet if left unpruned and pinkish to purple strap-like flowers, which makes for a great wall height.

‘Yoshino’ Japanese cryptomeria
Photo by Karen Russ, ©HGIC, Clemson Extension

A yaupon holly cultivar (Ilex vomitoria ‘Roundleaf’). John Ruter, University of Georgia, Bugwood.org Creative commons license.

Thuja plicata: Giant Arborvitae. Credit: Ed Gilman, UF/IFAS

Podocarpus macrophyllus or Japanese Yew. Credit: UF/IFAS

These plants are some of the selections homeowners may choose to start their natural walls. Given time, these shrubs will develop into a dense screen for the interruption of unwanted light or noise. To learn more about the aforementioned plant material, contact your local UF / IFAS extension agent.

Applying Florida Friendly Landscaping™ Principles During Hurricane Recovery

Applying Florida Friendly Landscaping™ Principles During Hurricane Recovery

Tree debris snowman

Storm debris turned into holiday cheer in Bayou George. Photo: J_McConnell, UF/IFAS

By the time this article publishes, we will be more than 70 days since Hurricane Michael toppled or damaged an incredible number of trees in the Panhandle. Enormous piles of once stately shade trees line the streets in neighborhoods and business districts in. The cleanup efforts have been phenomenal, over 4 million cubic yards of storm debris picked up in Bay County to date, but there is still a long way to go in the recovery process.

So, as gardeners, how can you help our community get back on track amidst your own struggles to recover? A few Florida Friendly Landscaping™ Principles come to mind.

  • #1 Right Plant, Right Place – as you rebuild your landscapes, make sure to choose the appropriate plant for the location. Consider mature size and give those plants space to thrive!
  • #4 Mulch – do you have bare ground that will eventually become landscape beds or turf but no resources or time to replant yet? Consider mulching the area to keep soil from eroding and to help improve soil though decomposition of natural products. Hint – see Recycling for free sources!
    • Mulch tips https://sfyl.ifas.ufl.edu/media/MulchBrochure.pdf
      • keep mulch 12 inches from tree trunks
      • recommended depth in beds or under dripline of tree canopy (excluding within 12” of trunk) is 2-3 inches
      • leave an 18-24 inch buffer around building foundations mulch free to reduce conducive termite conditions
  • Potted plant on stump

    Dress up stumps with plants and whimsical designs. Photo: D_VanderMeer, UF/IFAS Master Gardener

    #7 Recycle – driving around town I have seen some really creative uses for stumps, trunks, and branches that homeowners have constructed and messages of hope that bring a smile to my face. Another method of recycling is to use the chipped vegetative debris as mulch, either available as “utility mulch” by cities and counties or you may have some in your own yard right now.

    • Utility mulch does come with some words of caution because there is an increased risk of introducing weeds to your landscape with untreated storm debris. However, if you need mulch for pathways or planting beds you will be helping your community’s cleanup effort by reducing waste accumulation. Just watch for “volunteer” plants and manage as needed.

In Bay County, there are 4 locations where you can load and haul off your own utility mulch from storm debris

  • Under the Oaks Park – 5843 E. U.S. 98, Panama City, FL 32404
  • G. Harder’s Park – 8110 John Pitts Rd., Panama City, FL 32401
  • Chapman Park – 2526 Rollins Ave., Bayou George, FL 32404
  • Laird Park – 6310 Laird Park Rd., Panama City, FL 3240

For sources in your county, check with your Solid Waste Department for utility mulch availability.

Post Hurricane Landscape Care:  Replant Smartly with Hurricane Resistant Trees

Post Hurricane Landscape Care: Replant Smartly with Hurricane Resistant Trees

After a devastating windstorm, as we just experienced in the Panhandle with Hurricane Michael, people have a tendency to become unenamored with landscape trees.  It is easy to see why when homes are halved by massive, broken pine trees; pecan trunks have split and splayed, covering entire lawns; wide-spreading elms were entirely uprooted, leaving a crater in the yard.  However, in these times, I would caution you not to rush to judgement, cut and remove all trees from your landscape.  On the contrary, I’d encourage you, once the cleanup is over and damaged trees rehabilitated or disposed of, to get out and replant your landscape with quality, wind-resistant trees.

First, it’s helpful to take a step back and remember why we plant and enjoy trees and the important role they play in our lives.  Beyond the commercial aspect of farmed timber, there are many reasons to be judicious with the chainsaw in the landscape and to plant anew where seemingly sturdy trees once stood.  For example, trees provide enormous service to homes and landscapes, from massive cooling effects to aesthetic appeal.  Take this thermal satellite image of Hurricane Michael’s path that simultaneously shows the devastation of a major hurricane and the role trees play in the environment.

Lightly shaded area showing higher ground temperatures from loss of vegetation.

In the lighter colored areas where the wind was strongest and catastrophic tree damage occurred, the ground temperatures are much higher than the unaffected areas.  Lack of plant life is entirely to blame.  Plants, especially trees, provide enormous shading effects on the ground that moderate ground temperatures and the process of transpiration releases water vapor, cooling the ambient air.  Trees also lend natural beauty to neighborhood settings.  There is a reason people termed the hardest hit areas by Michael “hellscapes”, “warzones”, etc.  Those descriptions imply a lack of vegetation due to harsh conditions.  In this respect, trees soften the landscape with their foliage colors and textures, create architecture with their height and shape, and screen people from noise, unpleasant sights and harsh heat.

Though all trees give us the benefits outlined above, research conducted by the University of Florida over a span of ten major hurricanes, from Andrew to Katrina, shows that some trees are far more resistant to wind than others and fare much better in hurricanes.  In North Florida, the trees that most consistently survived hurricanes with the least amount of structural damage were Live Oaks, Cypresses, Crape Myrtle, American Holly, Southern Magnolia, Red Maple, Black Gum, Sycamore, Cabbage Palm and a smattering of small landscape trees like Dogwood, Fringe Tree, Persimmons, and Vitex.  If one thinks about these trees’ growth habits, broad resistance to disease/decay, and native range, that they are storm survivors comes as no surprise.  Consider Live Oak.  This species originated along the coastal plain of the Southeastern United States and have endured hurricanes here for several millennia.  Possessing unusually strong wood, they have also developed the ability to shed the majority of their leaves at the onset of storms.  This defense mechanism leaves a bare appearance in the aftermath but allows the tree to mostly avoid the “umbrella” effect other wide crowned trees experience during storms and retain the ability to bounce back quickly.  Consider another resistant species, Bald Cypress.  In addition to having a strong, straight trunk and dense root system, the leaves of Bald Cypress are fine and featherlike.  This leaf structure prevents wind from catching in the crown.  Each of the other listed species possess similar unique features that allow them to survive hurricanes and recover much more quickly than other, less adapted species.

Laurel Oak split from weak branching structure.

However, many widely grown native trees and exotic species simply do not hold up well in tropical cyclones and other wind events.  Pine species, despite being native to the Coastal South, are very susceptible to storm damage.  The combination of high winds and beating rains loosens the soil around roots, adds tremendous water weight to the crown high off the ground, and puts the long, slender trunks under immense pressure.  That combination proves deadly during a major hurricane as trees either uproot or break at weak points along the trunk.  In addition to pines, other widely grown native species (such as Pecan, Laurel Oak and Water Oak) and exotic species (such as Chinese Elm) perform poorly in storms.  Just as the trees that survive storms well possess similar features, so do these poor performers.  We’ve already mentioned why pines and hurricanes don’t mix well.  Pecan, Laurel Oak, and Water Oak tend to have weak branch angles and break up structurally in wind events.  The broad spreading, heavy canopy of trees like Chinese Elm cause them to uproot and topple over.  It would be advisable when replanting the landscape, to steer clear of these species or at least site them a good distance from important structures.

This piece is not a warning to condemn planting trees in the landscape; rather it is a template to guide you when selecting trees to replant.  Many of our deepest memories involve trees, whether you first climbed one in your grandparent’s yard, fished under one around a farm pond, or carved your initials into one in the forest.  Don’t become frustrated after a once in a lifetime storm and refuse to replant your landscape or your forest and deprive your children of those experiences.  As sage investor Warren Buffett once wisely said, “Someone is sitting in the shade today because someone planted a tree a long time ago.”

For these and other recommendations about how to “hurricane-proof” your landscape, contact your local UF/IFAS Extension Office.  Plant a tree today.

See the Forest for the Trees

See the Forest for the Trees

Trees have a pretty bad reputation in north Florida these days. They’re on our homes, cars, streets, power lines, and all over the yard causing a lot of grief. While my heart goes out to all of those dealing with trees in places they shouldn’t be, now’s a good time to remember all the reasons we should want trees around. It’s also a good time to review how to minimize tree impacts from future storms.

An older, poorly branched loblolly pine in Tallahassee. Credit: Mark Tancig

Benefits of Trees

Beyond being a huge source of oxygen, necessary for many organisms to live, trees provide other benefits such as well. According to a recent analysis of Tallahassee’s urban trees, approximately three million pounds of pollutants, such as carbon monoxide, nitrogen dioxide, ozone, sulfur dioxide, and particulate matter, are reportedly removed each year. The same report calculated that half a billion gallons of precipitation was intercepted by these trees rather than becoming stormwater runoff, reducing impacts of erosion and non-point source pollution. These trees also saved citizens an estimated one million dollars. Total annual benefits to the citizens was over $15 million per year! Researchers have found that trees increase residential or commercial property values an average of 7%!

Ways to Minimize Tree Failure

Select Replacement Trees Wisely

While very few trees could make it through sustained winds of 155 mph, replanting trees sooner will help communities see the benefits mentioned above and help them return to their former beauty. Even the most wind-resistant trees are likely to fail in a storm like Hurricane Michael. UF/IFAS researchers have studied wind-thrown trees following hurricanes and have found these trees to be some of the most wind-resistant – hollies (Ilex spp.), southern magnolia (Magnolia grandiflora), live oak (Quercus virginiana), cypress (Taxodium spp.), cabbage palm (Sabal palmetto), and, interestingly, sparkleberry (Vaccinium arboreum).

The least wind-resistant trees include pecan (Carya illinoiensis), tulip poplar (Liriodendron tulipifera), laurelcherry (Prunus caroliniana), laurel oak (Quercus laurifolia), water oak (Quercus nigra), southern red oak (Quercus falcata), red cedar (Juniperus virginiana), pines (Pinus spp.), and Chinese elm (Ulmus parvifolia).

When replanting, consider planting at least three trees in a group rather than an individual tree, as researchers found that trees in groups fared better.

An older water or laurel oak. Credit: UF/IFAS.

Tree Care

With existing trees and newly planted trees, taking good care of the tree can help it withstand high winds. In addition to proper pruning techniques and providing adequate root zone space, paying close attention to minimize soil compaction and root zone disturbances will help create a stronger root system. Older trees should be regularly monitored for potential signs of decay.

An older oak with decay in trunk. Credit: UF/IFAS.

UF/IFAS has many great resources related to tree health and recovery after hurricanes. A search for Urban Forest Hurricane Recovery Program at our EDIS website (https://edis.ifas.ufl.edu) has several publications to help decide how to move forward and create a healthy urban forest. Let’s not allow our frustration with the tree on the roof to prevent us from recognizing that trees are good.