While the azalea blooms are beautiful, it’s hard to remember what the leaves looked like last summer. But, if you look carefully, you may see some off-colored, bleached out leaves. Those are from a piercing-sucking insect. Its azalea lace bug, Stephanitis pyrioides. They overwinter as eggs on the underside of infested leaves or in the leaf litter or mulch under the shrub. 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.
Damage caused by azalea lace bug, Stephanitis pyrioides (Scott), feeding. Photograph by James. L. Castner, University of Florida.
Both adults and nymphs have piercing-sucking mouthparts and remove sap as they feed from the underside of the leaf. Lace bug damage to the foliage detracts greatly from the plants’ beauty, reduces the plants’ 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.
Adult azalea lace bug, Stephanitis pyrioides (Scott). Photograph by Jamba Gyeltshen, University of Florida.
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).
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.
Azalea leaf with azalea lace bugs, Stephanitis pyrioides (Scott), and excrement spots. 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.
January to February is the ideal time to plant trees. During dormancy, all the energy in a tree is in the root system. They will establish very quickly. In the spring, they will be ready to grow leaves. Planting and establishing trees is all about managing air and moisture in the soil. The exception is palms. They are not technically trees and should only be planted in the late spring and summer. Three of the most common causes of poor plant establishment or tree death are planting too deep, under watering, and over watering. If appropriate trees are planted at the right depth and they are irrigated properly, the trees will thrive for years to come. As simple as this sounds, problems often arise that lead to poor establishment or plant failure.
Following ten critical steps can ensure proper tree planting:
1. Look up for wires and lights. Make sure that the tree species’ mature size will not interfere with any utility lines.
2. Find the topmost root and treat root defects. After removing the pot from the tree, remove all excess soil on the top of the root ball, until a root that is similar in diameter to the lower branches is located. That is the topmost root. Look for any roots that encircle the rootball, particularly close to the trunk. Remove any roots that will strangle the trunk. Cut all encircling roots at the point they turn to encourage root branching. Then, rough up or shave off all the roots on the perimeter of the rootball. If the tree is balled and burlapped, use a metal skewer to locate the depth of the topmost root.
Remove an inch or more for extremely rootbound trees.
3. Dig shallow and wide hole. Using the corrected rootball as a gauge, dig the hole slightly less shallow that the rootball. Loosen the top six inches of soil around the entire rootball.
4. Carefully place tree in hole. Lower the tree into the hole slowly.
5. Position top root 1-2 inches above landscape soil. Make sure that the rootball is above the surrounding soil grade. If balled and burlapped, the nylon straps, metal pins, burlap on top of the rootball, and wire basket above the grade will need to be removed.
6. Straighten tree. Check the tree from two directions at 90% angles from each other.
7. Add and firm backfill soil. Tamp soil with fingers, not feet. Do not stomp on the soil. It will compact the soil and reduce the oxygen to the roots.
8. Add mulch. Apply a 2–3-inch layer of natural mulch out to the perimeter of the trees branches, or beyond if possible. However, there should be 1 inch or less mulch on top of the rootball. Do not allow mulch to touch the trunk.
9. Stake and prune if needed. If there is a strong steady wind, staking is necessary. Otherwise, don’t stake. Make sure to do all structural pruning is done at planting time. Establish a central leader and remove crossing branches. But do not remove the lower branches. Just reduce the length. The tree needs to bring food to the lower portion of the trunk to increase the diameter.
10. Water the tree. Don’t walk away until the tree has been watered. Apply at least ½ gallon. The tree will need to be watered twice a week for 20-30 weeks. The larger the tree, the more water needed at each event. However, if the water doesn’t perk in within a few minutes, reduce the amount being applied. Overwatering can be as harmful as underwatering.
The flower of the Christmas season is the poinsettia, a tropical plant from Mexico that changes its leaf color when the daylength changes. Poinsettias were originally noticed for their bright red color and are now available in many colors, shapes and sizes, thanks to decades of work by plant breeders. As much as we love them, caring for poinsettias during and after the holiday can be a challenge. Here are a few tips to extend the bloom for a longer period and encourage it to grow for the months to come!
Photo credit: Tyler Jones.
Provide plenty of sunlight. A sunny window facing south is ideal. Be careful to not let the leaves touch the glass. Keep temperatures around 55-60F at night and 65-70F during the day.
Keep soil slightly moist on the surface. Wait until the surface feels dry before watering, then add just enough to soak in. If water collects below the pot, pour it out. Those decorative wrappers make it hard to tell, so be sure to check. However, don’t wait for wilting before watering as that is too dry. Both overwatering and underwatering can lead to wilting and excessive leaf drop. Check the soil each day.
Don’t fertilize while “blooming”. While the colored parts of poinsettias are actually modified leaves called bracts and the true flowers are the tiny yellow centers, we often refer to the entire non-green portion as a bloom. The plant can maintain its nutritional needs throughout the flowering time without additional fertilizer.
In the spring, cut the plant back, fertilize and move outside. Remember, poinsettias require temperatures to always stay above 60F. If we receive any cool nights, bring it in for the night. Let the rootball become quite dry throughout April. You may have to move it under a cover if the April showers are occurring every few days.
If you want to try your luck at re-blooming, re-pot it in a slightly larger container and cut it back to about 4” high in mid-May. Keep it in nearly full sun. A little shading in the heat of the day is helpful. Water consistently and fertilize every two weeks with a water-soluble, complete fertilizer. As it grows, you will need to pinch the plant back every six weeks or so until October, I usually remove about half of the stem that has grown out. To get coloration in time for Christmas, find something dark to cover the plant or move it to a dark location each day. The poinsettia must be in complete darkness from 5 p.m. to 8 a.m. until the leaves start to turn color, usually 10 weeks. That means moving or covering and uncovering at the same time every day. Any deviation will delay the color change. Once you see a complete set of leaves coloring, the plant can be exposed to regular daylengths. If this sounds like too much work, spent poinsettias do make good compost and garden centers will be happy to sell you a new one!
Remember, poinsettia sap does contain a latex-like chemical that can cause allergic reactions. Small animals, young children, and adults with allergies should not handle poinsettias. If eaten, get medical attention immediately.
Throughout history the evergreen tree has been a symbol of life. “Not only green when summer’s here, but also when it’s cold and dreary” as the Christmas carol “O Tannenbaum” says.
While supporting the cut Christmas tree industry does create jobs and puts money into the local economy, every few years considering adding to the urban forest by purchasing a living tree. Native evergreen trees such as redcedar make a nice Christmas tree that can be planted following the holidays. The dense growth and attractive foliage make redcedar a favorite for windbreaks, screens and wildlife cover.
The heavy berry production provides a favorite food source for migrating Cedar Waxwing birds. Its high salt-tolerance makes it ideal for coastal locations. Their natural pyramidal-shape creates the traditional Christmas tree form, but can be easily pruned as a street tree.
Two species, Juniperus virginiana and Juniperus silicicola are native to Northwest Florida. Many botanists do not separate the two, but as they mature, Juniperus silicicola takes on a softer, more informal look.
Cedar waxwing, Bombycilla cedrorum
When planning for using a live Christmas tree there are a few things to consider. The tree needs sunlight, so restrict its inside time to less than a week. Make sure there is a catch basin for water under the tree, but never allow water to remain in the tray and don’t add fertilizer. Locate your tree in the coolest part of the room and away from heating ducts and fireplaces.
After Christmas, install the redcedar in an open, sunny part of the yard. After a few years you will be able to admire the living fence with all the wonderful memories of many years of holiday celebrations. Don’t forget to watch for the Cedar Waxwings.
Diascia (Twinflower) in full bloom! Photo courtesy of Walton County Master Gardener Andrea Schnapp.
Since 2005, multiple varieties of Diascia have added to the U.S. fall market of winter flowering plants. Its delicate flowers are far from being ordinary though. In the early part of the last century most British gardening encyclopedias listed just one diascia – Diascia barberae – derived from seed collected by Col. J. H. Bowker and sent by Mrs. Barber to Kew Gardens, England, in 1870. Annual and perennial diascias had, of course, already been discovered and classified by several botanists visiting South Africa much earlier. The dainty, little annual, Diascia barberae, is not a very showy flower, but one which will appeal to the true flower lover. The flowers are rosy pink with yellow-green spots in the throat. The flowers are lipped, being related to the Snapdragons, but have two spurs on the lower lips, and are sometimes called twinspur.
It was not until John Kelly was given a plant called Diascia cordata by Edrom Nurseries in 1971 that anything notable happened to diascias again. He took pollen from his Diascia cordata and applied it to one flower of Diascia barberae. Of the nine seeds he obtained, just one was worthy of attention. He named it Diascia ‘Ruby Field’ (not for the color of the flowers, but for a lady who devoted her live to the long-term care of deprived children). Despite the popularity of this new, hardy hybrid, little more happened with diascias for yet another decade.
Diascia ‘Romeo’. Photo courtesy of Walton County Master Gardener Andrea Schnapp.
The boom in the diascia trade began only recently. Today’s diascia offers larger flowers, larger plants with a more open growth habit and colors ranging from scarlet through salmon and coral into pink. They bloom throughout the cooler weather and may behave as a perennial in warmer sites. But, the uniqueness of their flower structure and ecological role are as fascinating as the flower is beautiful. The common name of twinspur refers to the two downwardly pointing spurs found on the back of the flower. The spurs contain an oil which is collected in the South Africa wild by Rediviva bees. The female bees have unusually long, hairy forelegs that are used to collect the oil to feed her larvae. However, the Greek origin of the Diascia name doesn’t refer to the spurs, but rather the two sacs found in the upper part of the corolla. The flower petals help the bees to orientate themselves to the oil glands of the spurs. While North Florida isn’t home to the Rediviva bee, we can grow Diascia and it is a wonderful opportunity to show the unique connection insects and plants can have. Look for other specialized flower structures and you will find other animals that fit them perfectly, even within the species found in the Panhandle.
