by Matt Lollar | Jun 4, 2018
Normally we think of rust as something that deteriorates metal, but a number of different fungal rusts can affect plants in the garden. Rust disease can affect corn plants, cedar trees, and even blueberry bushes. Just like the broad range of plant species that can be plagued by rust, there are a number of species of rust fungal spores floating around and ready to infest your garden. This article will focus on leaf rust of blueberry.
Blueberry leaf rust on the top of a leaf. Photo Credit: Philip Harmon, University of Florida/IFAS Extension.
Leaf rust of blueberry in Florida is caused by the fungus Pucciniastrum vaccinii. Although the common name of the disease is “leaf rust”, the disease can also infect the stems and fruit of blueberry plants. The disease causes small, round spots visible on the tops of leaves. Spots will multiply and the leaves will eventually yellow and fall off. Young stems and green fruit can also become infected as the disease progresses. Bright orange lesions will form on stems and fruit as the thousands of microscopic spores conjoin. The clusters of spores are easily wiped or washed off of plant material. When spores dry out, they become airborne and can be transferred to nearby plants.
Blueberry leaf rust on fruit. Photo Credit: Philip Harmon, University of Florida/IFAS Extension
The rust fungus thrives in hot, humid, wet conditions. A number of cultural practices can be adopted to reduce disease progression and survival.
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Irrigation
Disease persistence can be reduced by limiting the amount of water that contacts the plant leaves. Water the base of plants or install drip irrigation for your bushes rather than watering from overhead. If overhead irrigation is the only option, then water plants in the morning rather than in the evening. This allows the leaves to dry out over the course of the day.
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Pruning
Removal of approximately 25% of the oldest canes in late winter before spring growth begins will stimulate the production of new canes and should result in plants with canes of different ages and will provide a good mix of vigorous branching and fruit production. Moderate summer pruning can also improve yield and shoot growth. When pruning, cut out vigorous shoots that are growing well beyond the desired canopy height and are in the interior portion of the bush. This will promote a more open growth habit and help with air circulation on the remaining plant material. Some vigorous canes developing from the ground and growing on the outside of the bush can be topped to stimulate branching and flower bud formation.
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Mulch
Pine bark mulch helps with establishment of young plants and helps keep soil pH low in existing plantings. A layer of aged pine bark 3 inches deep extending about 2 feet out from the plants will provide a good growing medium for surface feeder roots. Pine straw can be used if pine bark is unavailable. Mulch also moderates soil temperature, helps keep weeds at bay, and adds organic matter to the soil. Make sure to keep mulch raked back about three inches away from the plant canes to provide good air circulation to the roots.
Hopefully this article has given you some tips to have a good blueberry crop for years to come. For more information on growing blueberries in Florida, please visit the University of Florida/IFAS EDIS Publication: Blueberry Gardener’s Guide.
by Daniel J. Leonard | May 4, 2018
H. macrophylla ‘Bloomstruck’
Photo courtesy of Andrea Schnapp
Generally, when folks find out what I do for a living, among the first questions asked is “What is your favorite plant?” Being somewhat of a plant nerd, that can be a tough question to answer! However, I usually circle back to the same answer, “Hydrangea”. There are many reasons my fellow gardeners and I love hydrangeas. It’s undeniable that few plants conjure more fond memories of summers gone by or cause more impulse purchasing at nurseries than a hydrangea in full, billowy bloom. Additionally, few specimen shrubs give more floral firepower and ask so little of the gardener in return. My own love affair with hydrangea stems from my first propagation experience, a softwood cutting of Hydrangea macrophylla ‘Nikko Blue’ (taken with the help of someone who knew a lot more about what they were doing than I did) that, seemingly magically, sprouted roots in a makeshift greenhouse, a cypress box with an old, crusty, sliding glass door. Hydrangeas hooked me. However, even with all of those attributes to its name, Hydrangea, as a genus, remains underappreciated and underutilized in modern landscapes. Let’s shed some light on the two primary reasons for gardeners’ failure and frustration with hydrangeas in the landscape and highlight some of the best Hydrangea species and cultivars to look for at the nursery!
First, hydrangea has a reputation as being a high water user. As the name (hydrangea comes from “hydor”, which is Greek for water) might suggest, hydrangeas are indeed water sensitive. However, this does not necessarily mean they require more or less water than other plants, rather they simply betray drought quicker than most other plants. This feature makes hydrangea particularly useful in the landscape as an indicator plant. As a general rule, hydrangeas (particularly those planted in too much sun) wilt in the afternoon heat; this is totally normal. However, if the plants remain wilted the next morning, it is an indicator to the gardener that irrigation is required! If they don’t get irrigation soon after telling you they need it, the plants may begin to decline. Rather than being viewed as a drawback, think of this feature as an early warning system. Name another plant that looks out for us gardeners like that!
The second primary reason people fail with hydrandea is improper site selection. Attempting to grow hydrangea in full sun in Florida leads to less than spectacular results. All species of hydrangeas are most happy when sited to receive at least some afternoon shade, if not filtered shade throughout the entire day. Exposure to blistering afternoon sun is problematic and results in increased wilting from heat stress, increased irrigation requirements and “bleached” flower coloration. Remember, there are fewer frustrating things than growing the right plant in the wrong place!
Now that you know how not to fail with hydrangeas, it’s time to select the proper plant for your property! Three primary species perform noticeably better here than the rest of their kin and deserve the gardener’s consideration in Northwest Florida: H. macrophylla (Bigleaf Hydrangea), H. quercifolia (Oakleaf Hydrangea), and H. paniculata (Panicle Hydrangea).
H. macrophylla
H. macrophylla, the old-fashioned hydrangea everyone’s grandmother grew, is truly one of the standouts in the shady, Southern landscape and commands attention when in flower. Sporting giant “mopheads” of inflorescences in gorgeous hues of blue (or pink, depending on soil pH), H. macrophylla is an extremely low maintenance plant, requiring only periodic irrigation and infrequent fertilizer; H. macrophylla even tolerates salt spray and can be grown on the Gulf Coast! By far, the greatest percentage of questions I receive concerning H. macrophylla involve plants not flowering because of pruning at the wrong time of year. For best flowering results, time pruning of once-blooming traditional cultivars like ‘Nikko Blue’ soon after flowering is finished in late summer. These plants set flower buds on the previous season’s wood; pruning older cultivars in the fall or winter may rejuvenate the plant but will prevent flowering the next year! Fortunately, over the last twenty years, advances in Hydrangea breeding have given gardeners the option of planting remontant cultivars that bloom on current season’s wood. Commonly sold remontant cultivars like ‘Endless Summer’, ‘Penny Mac’, ‘Bloomstruck’, and ‘All Summer Beauty’ have an early summer flower display like the traditional types but then continue to flower periodically throughout the rest of the summer! Even better, they may be pruned at any time without worry of damaging the next season’s flower show!
H. quercifolia (Oakleaf Hydrangea) Photo Courtesty of Andrea Schnapp
Those looking to diversify their hydrangea collection should next look to the native Oakleaf Hydrangea (H. quercifolia). The Oakleaf Hydrangea is a Florida native, growing wild on the steep, shady ravines along the northern end of the Apalachicola River. If the plants never flowered, the Oakleaf would be worth planting; its massive leaves, oak-shaped as the name suggests, can grow up to a foot in length and provide some of the best fall foliage color available to Floridians. However, the real show, as with all hydrangea species, are the flowers. This species flaunts 8”-10” white, panicle shaped flowers that are held elegantly above the coarsely textured foliage. In addition to these features, Oakleaf Hydrangeas couldn’t be easier to grow; obtaining heights up to 10’ and asking very little of the gardener other than adequate irrigation and some shade in the heat of the day! Look for the author’s favorite cultivars: ‘Alice’, ‘Semmes Beauty’, and ‘Snowflake’. Each of these cultivars and selections of the common species H. quercifolia perform very well in Northwest Florida.
H. paniculata ‘Quickfire’
Photo courtesy of Andrea Schnapp.
Finally, the newest hydrangea species introduced to Florida gardens, H. paniculata, has made significant inroads in the landscape industry over the last decade. Primarily grown as the cultivar ‘Limelight’, H. paniculata overcomes some of the weaknesses of the two aforementioned species, namely it tolerates full-sun and persists on much less water, making it a potentially more sustainable plant for many landscapes. This plant, like the remontant H. macrophylla cultivars, blooms on new wood and even seems to enjoy a hard pruning each winter; plants pruned this way seem to be more vigorous the next season and produce larger greenish-white flower panicles than unpruned specimens. Though it is a relative newcomer, H. paniculata, particularly ‘Limelight’, is a worthy addition to any landscape.
As you can see, there is a hydrangea for every yard and no true Southern landscape is complete without a few. When perusing your local garden center this summer, look for the selections and species mentioned above, plant properly, and enjoy the ensuing annual flower show for many years into the future! Who knows, you may be hooked by hydrangeas as I once was!
by Matthew Orwat | Apr 17, 2018
Monsieur Tillier – Tea rose from the late 1800s. A good choice where a large, free-flowering shrub is needed – Image Credit Matthew Orwat
Home Gardeners, when they think of roses, their mind inevitably turns to the ‘Knockout’ rose and its offspring. That’s fine, there’s nothing wrong with ‘Knockout’ roses, it makes a great ornamental landscape plant, and it’s easy to propagate.
With all the ‘Knockout’ mania, since the early 2000s, many garden roses, that are well adapted to the Northwest Florida climate, have been left out of the home garden to a large degree.
Several roses, which were grown in Florida commonly in the last hundred years, and recommended by former University of Florida president H. H. Hume in his book “Gardening in the Lower South,” are still grown here today. To obtain these roses gardeners must look to small nurseries scattered throughout central Florida and Alabama, or order them from larger nurseries in Texas where the “Texas A&M Earthkind Rose Program” has taken off.
Below are a few examples of easy to grow roses, that are just as disease resistant as the ‘Knockout,’ but offer more variety in color and form that home gardeners might enjoy as much as or more than ‘Knockout’. They have been grown successfully throughout southern Texas for over 30 years, and at the Washington County Extension Office for the past seven years without spraying fungicides or insecticides. Several of these cultivars were also involved in a 3-year rose trial at the UF/IFAS North Florida Research and Education Center, in Quincy.
One caveat I have regarding these roses is that disease resistance is lessened when irrigated with overhead irrigation. Even the most disease resistant roses will develop issues if leaves are constantly left wet.
Belinda’s Dream makes a moderately sized shrub and produces large flowers, especially in the spring and fall. Image Credit – Matthew Orwat
‘Belinda’s Dream’
‘Belinda’s Dream‘ was bred by Texas A&M Professor Robert Basye in 1988, as a culmination of years of intense breeding and selection for disease resistant landscape and cut flower roses. It makes a 4-5 foot shrub that grows about 3 feet wide. Apple-green foliage clothe its pleasing shrub form. It’s free flowering but not overly vigorous, so it’s easy to keep in bounds. Disease resistance is high, there’s rarely any blackspot of note, under no-spray conditions, and only slight powdery mildew in a few years when conditions are favorable for fungus development.
In cool spring or fall conditions, the clear pink flowers can top six inches in diameter, and contain over 200 petals, but regular hot conditions during the summer usually reduce flower size to four inches. This rose loves to be part of mass plantings, particularly when planted 3 feet apart in a triangular formation. It has a reputation as being moderately easy to propagate.
Rosette Delizy is very colorful and disease resistant. A great addition where a spot of color is needed – Image Credit Matthew Orwat
‘Rosette Delizy’
‘Rosette Delizy‘ is a French Tea rose that was introduced to the U.S. nursery trade in the mid-1920s. Since it was bred before the days of modern fungicides, it sports excellent resistance to disease. It shows no powdery mildew, and only the occasional leaf with blackspot under no-spray conditions.
This is strictly a rose for the coastal south, since it does not like cold temperatures, and cannot thrive north of zone 7b without protection.
Color is striking, opening yellow with petal edges changing to pink as the flowers age. Cooler weather brings out deeper russet and maroon tones. It has a light “tea” fragrance. This mannerly shrub gets 4-5 feet tall and 3-4 feet wide. It requires very light pruning, and can actually be killed from heavy-handed gardeners with shears in hand. Minor flaws noted in this rose are that it is somewhat sparsely foliated, and somewhat difficult to propagate.
Madame Antoine Mari – The perfect buttonhole rose produces flowers with delicate, soft colors perfect for arranging. This rose is a mannerly grower suitable for smaller landscapes. Image Credit Matthew Orwat
‘Madame Antoine Mari’
‘Madame Antione Mari’, a Tea rose, was introduced in 1900 when the buttonhole rose was all the rage. Massive quantities of perfectly formed delicate buds of pink and ivory quickly open into 3 inch flowers that decorate the bush like butterflies fluttering in the wind. Re-bloom is fast. Additional interest in the landscape is created by the deep red color of new foliage.
This makes a mannerly shrub for the small landscape, easily kept at 3-4 feet tall, and 5-6 feet wide by light pruning. Disease resistance is above average in a no-spray garden, with very low blackspot infection rates, and only occasional powdery mildew. This rose has been found to be easily propagated with the author reaching near 100% success rate.
Mrs. B. R. Cant at the Quincy rose trial in 2013.
‘Mrs. B. R. Cant’
No mention of easy to grow roses is complete without the mention of ‘Mrs. B. R. Cant’. In the trials UF/IFAS horticulturists performed at Quincy and Plant City, this variety was rated the best performer. It has been in continuous cultivation since 1901, and is often found at old home sites and gardens in Washington County.
This makes a large garden rose, easily topping 8 feet in height, and just as wide. Deep pink flowers are borne profusely from March to first frost. Disease resistance is outstanding, and it’s easy to propagate. Plants are densely clothed in medium green leaves. This rose is often grown in hedges as a substitute for a fence. One of the best all-around garden roses for the gulf south.
Nursery Availability
I provide presentations at workshops on these roses multiple times a year, throughout the Florida Panhandle. The recurring question I get is, “Where are these roses available locally?” Hopefully this article will inspire some local gardeners to try these easy to grow roses, and others, since these are just a few of the roses available that do very well in North Florida under no spray conditions. If you are interested in more information, contact, Matthew Orwat at UF/IFAS Extension Washington County.
by Beth Bolles | Apr 9, 2018
The change in North Florida temperatures from cooler to warmer is making many winter weeds more noticeable as they begin to flower and form seed. Not all of these plants should be considered for mowing or hand pulling. There are several wildflowers that grow in landscape beds and thinning areas of lawns and can be enjoyed before consistent heat returns.
Toadflax flowers are held above the foliage and are light purple. Photo by Beth Bolles, UF IFAS Extension Escambia County
One very delicate wildflower that is growing now is the Toadflax, Linaria canadensis. The leaves are very small and grow low on the ground. Thin flower stalks grow several inches and are topped with light purple flowers. Although toadflax pops up in beds and lawns don’t be so quick to pull it out. This wildflower is a host to the Buckeye butterfly, one of our earlier visitors to gardens. If you look closely you may even see the tiny black, spiny caterpillar eating toadflax leaves. Visit the UF publication on the Buckeye butterfly to learn more.
Adult buckeye butterflies are common in landscapes in early spring and late summer. Photo by Lo Sitton, UF IFAS Extension Escambia County
