Look Between the Blooms

Look Between the Blooms

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.
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.
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 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.

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

Native Azaleas in Bloom

Native Azaleas in Bloom

piedmont azalea

Piedmont azalea (Rhododendron canescens) flowers. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Native azaleas are stunning this time of year.  These deciduous shrubs (and sometimes small trees) often go unnoticed until they bloom in the spring.  Three species native to Florida are the piedmont azalea (Rhododendron canescens), the Florida flame azalea (Rhododendron austrinum), and the swamp azalea (Rhododendron viscosum).  Piedmont azaleas have whitish to pinkish blooms, Florida flame azaleas have yellow to orange blooms, and the white blooms.  All three species have a wonderful honeysuckle-like, sweet fragrance.  All three serve as outstanding focal points in the landscape.

Native azaleas and other deciduous azaleas have varying site preferences.  Like other azaleas, piedmont and Florida flame azaleas prefer moist, well-drained, acidic soils.  However, as the name would suggest, the swamp azalea tolerates wetter locations.  All three species prefer partial shade (morning sun and afternoon shade are best) locations and can grow up to 15 feet tall.

Rhododendron x 'Aromi Sunny-Side-Up' in bloom.

Rhododendron x ‘Aromi Sunny-Side-Up’ in bloom. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

In addition to these beautiful native azaleas, a number of deciduous hybrids have been developed.  Aromi hybrids have been bred to tolerate heat and humidity.  These azaleas were developed from four native species ()from Gene Aromi in Mobile, AL.  He developed more than 100 cultivated varieties (also referred to as cultivars).  Popular cultivars in the market include ‘Centerpiece’, ‘Aromi Sunrise’, and ‘Aromi Sunny-Side-Up’.

Deciduous azaleas do not require a lot of fertilizer.  A controlled release or slow release, acid forming (specifically formulated for azaleas or blueberries) fertilizer is recommended.  A fertilizer nutrient ratio of or close to 2-1-1 (N-P-K) should be selected.  Plants should be fertilized in spring or early summer, never in the fall or winter.

More information on azales, native and nonnative, can be found on the UF/IFAS Gardening Solutions website.

Satsuki Azaleas: Elegant small evergreens with oversized flowers

Satsuki Azaleas: Elegant small evergreens with oversized flowers

Article written by Dr. Gary Knox, North Florida Research & Extension Center – Quincy, FL.

‘Gumpo Pink’ flowers are 3 inches in diameter and are pink with purplish pink dots and occasional white blotches on petals.

Background

In the times before re-blooming azaleas like Encore®, Bloom-A-Thon® and others, Satsuki azaleas were valued for late flowering that extended the azalea “bloom season”. Even with modern re-blooming azaleas, Satsuki azaleas still are appreciated as refined evergreen shrubs for the sophisticated garden or discerning plant collector.

“Satsuki” means “Fifth Month” in Japanese, corresponding to their flowering time in much of Japan. These azaleas were developed hundreds of years ago from their native Rhododendron indicum and R. eriocarpum. The Japanese selected cultivars more for their form and foliage than for flowering. These beloved plants were used in gardens as sheared boxwood-like hedges or pruned into rounded mounds that might resemble rocks or boulders in classical Japanese gardens. Their size and form also made them well adapted for training as bonsai. Most of the Satsuki azaleas in America were introduced in the 1930s by USDA.

Description

Satsuki azaleas are small evergreen shrubs that flower in April and May in north Florida, long after most older type azaleas have finished. Satsuki azaleas also are known for producing large, mostly single flowers up to 5 inches in diameter in colors of white, pink, red, reddish orange and purple. Often the flowers will include stripes, edging, blotches, spots or flecks of contrasting colors (Sometimes all on the same plant!) with more than 20 different color patterns recorded.

Satsuki azaleas have an elegant subtle charm, quite unlike the flashy, over-the-top, heavy blooming all-at-once Southern Indica azaleas like ‘Formosa’ and ‘George L. Taber’. Typically, Satsuki azaleas display a few large blooms at a time, allowing one to better appreciate their size and color patterns as contrasted against their fine-textured, dark green leaves. To make up for a less boisterous display, Satsuki azaleas flower over a longer timeframe, averaging about 8 weeks, with some flowering an amazing 14 weeks. In another contrast, most Satsuki azaleas grow smaller in size, in my experience reaching about 3 feet tall and wide in a five-year timeframe. The rounded to lance-shaped leaves of Satsuki azaleas also are demure, ranging in length from just ½ inch to no more than 2 inches.

Culture

Satsuki azaleas enjoy the same conditions as most other azaleas: light shade and moist, rich, well-drained soil.  Mulch regularly to maintain organic matter and help hold moisture. Fertilize lightly and keep the roots evenly moist. Minimal to no pruning is required. Satsuki azaleas also are well adapted to container culture. Their small size and fine textured leaves make these a favorite for bonsai enthusiasts since their small leaves, branching habit and mounded form naturally make them look like miniature mature “trees”.

Sources and Cultivars

Look for Satsuki azaleas in spring at garden centers or year-round at online nurseries. There are hundreds of cultivars but some popular types to look for include:

Gumpo Pink – 3-in. diameter light pink flowers with purplish pink dots and occasional white blotches

Gumpo White – 3-in. diameter white flowers with occasional pink flakes and light green blotches

Gyokushin – 3-in. diameter flowers are predominantly white but with light to dark pink dots and blotches

Higasa – flowers are 4 to 5 inches in diameter and are purplish pink with purple blotches

Shugetsu – also called ‘Autumn Moon’, 3-in. diameter flowers are white with a broad, bright purplish-red border

Tama No Hada – flowers are 4 to 5 inches in diameter and are white to pink with deep pink stripes; usually flowers in fall as well as spring

Wakaebisu – 2.5-in. diameter flowers are “double” (hose-in-hose) and are salmon pink with deep pink dots and blotches; this also flowers in fall as well as spring

References:

Chappell, M. G.M. Weaver, B. Jernigan, and M. McCorkle. 2018. Container trial of 150 azalea (Rhododendron spp.) cultivars to assess insect tolerance and bloom characteristics in a production environment. HortScience 53(9-S): S465.

‘Gumpo Pink’ flowers are 3 inches in diameter and are pink with purplish pink dots and occasional white blotches on petals.

‘Gyokushin’ flowers are white with occasional pink flecks and light green blotches.

‘Shugetsu’ has 3-inch flowers that have bright purplish-red border on edges of petals.

Galle, Fred C. Azaleas. 1985. Timber Press, Portland, Oregon. 486 pp.

 

Timing is Everything: Pruning Azaleas for Maximum Bloom Potential

Timing is Everything: Pruning Azaleas for Maximum Bloom Potential

Fall Pruned Azalea. Image Credit Matthew Orwat

Although Northwest Florida is well known for its beautiful Azalea displays every spring, many do not understand that these shows of bloom could be sacrificed completely by pruning at the wrong time.

Pruning Azaleas in the fall will result in a loss of spring bloom the following spring, since flower buds are initialized on previous year’s growth for most azalea cultivars.This means that they flower on growth put on throughout the previous growing season. If a gardener removes the previous season’s new growth, they are removing the blooms as well.

So, when is the proper time to prune Azaleas? The ideal time to prune is directly after the spring bloom. This will give the plant enough time to generate abundant new growth, thus maximizing bloom next spring. One might think that when growing the repeat blooming Encore azaleas, pruning time doesn’t matter. Should the need arise to prune these compact, repeat blooming shrubs the optimal time is directly after spring bloom and not after the final fall bloom cycle.

For more information on pruning Azaleas or on general Azalea culture, please read the UF / IFAS publication Azaleas at a Glance or check out the Pruning Azalea page on Gardening Solutions.

Pruning Azaleas for Color

Pruning Azaleas for Color

Azaleas are a beautiful shrub for the north Florida landscape, especially if pruned properly. Source: Larry Williams, UF/IFAS

The sight of azaleas in the north Florida spring just makes you feel good. They are so vibrant, and with such variation, that you can’t take your eyes off them. As an appreciator of these beautiful displays of color, nothing pains me more than to see an improperly pruned azalea during this time. If you must prune your azaleas, please, please only prune them once a year and only soon after flowering has ended! This public service announcement will hopefully ensure we all get to see the full azalea show. Otherwise, we’ll be left with mostly green hedges, some flowers uncomfortably tucked in the interior of the plants, or flowers poking out the sides like a middle-aged man’s balding head.

If pruned properly and at the right time, this azalea shrub would be a mass of flowers. Source: Mark Tancig, UF/IFAS.

The common flowering azaleas in landscaped settings are native to Japan and a relative of blueberries. They comprise many different hybrids, cultivars, and varieties of plants in the genus Rhododendron (Greek for rose-tree) and have been cultivated for centuries. Long ago, I’m sure, those who studied plants and tinkered with azaleas realized that their vegetative growth (new leaves and stems) ends soon after flower bud initiation. This means that later prunings, or multiple prunings throughout the year, will be taking off more developing flower buds than new leaf and stem growth.

To prevent depriving us all of less flowers, consider why – or if – they need pruning in the first place. Proper planning and planting can prevent azaleas, which naturally want to be a sprawling shrub, from growing into the sidewalk or driveway. If you’ve inherited azaleas that may be the right plant, but slightly in the wrong place, they can be heavily pruned every couple of years to keep them in check, and can even be transplanted. Azaleas are not a good choice for formal hedges. If given the right place and enough space, the only required pruning would be dead, diseased, or crossing branches.

If you decide you need to prune – whether to knock back for space or for general shape – only bust out the loppers once the flowers have withered on the ground… and then lock those loppers away so that you won’t be tempted. If you have landscapers working for you, remind them to keep the hedge trimmers away from the azaleas.

Azaleas are vibrant, even in black and white! Source: Florida State Archives, Florida Memory Project.

For the love of flowers, please prune azaleas thoughtfully, and share this information with others

P.S. We also have several species of native azaleas (including Rhododendron austrinum and Rhododendron canescens) that can be a beautiful addition to the landscape.