by Mary Salinas | Sep 23, 2013
Is the newest growth on your sago palm turning yellow, brown, frizzy looking and dying – is it a pest or disease or something else?
Photo credit: Mary Derrick
This sago palm is suffering from a classic case of manganese deficiency. When sago palms lack manganese, the newest leaves will develop yellow splotches or be entirely yellow. As the leaves die, they turn brown and take on a frizzled appearance. Sometimes the leaves or fruit may be smaller than normal. If left unchecked, the sago usually dies.
Manganese is a micronutrient required by all plants for normal, healthy growth and is most available for plant uptake when the soil pH is between 5.5 and 6.5. Soils in the Florida panhandle are often naturally low in manganese and then what available manganese is present can be unavailable for the plant to use if the pH of the soil is much above 6.5. Also, manganese tends to be leached from the soil when the pH is below 5.5. Soil pH and nutrient testing is useful to determine if soils are nutrient deficient. Contact your county Extension office for information on getting that done.
[notice]Before treating, rule out an infestation of Asian cycad scale. Click here for a UF IFAS Extension publication on this damaging insect. Be aware that both are common problems for sago palms and that your sago may be afflicted with both![/notice]
If this is happening to a sago palm, the good news is that it is easy to correct. Manganese sulfate is readily available at garden centers, feed &seed stores and independent nurseries. Just make sure to get manganese sulfate and don’t confuse it with magnesium sulfate (Epson salts). The amount of manganese sulfate necessary to correct this deficiency will vary with its size, soil type and pH. Sago palms in sandy, acidic soils require less manganese sulfate than those in high pH soils. One ounce is sufficient for a very small plant in sandy, acidic soil. A very large sago in a high pH soil may require about five pounds, however. Spread the product evenly over the root zone and water in with about a half inch of water.
The affected leaves cannot be cured but new growth should return to normal. If the new growth is still affected, an additional application of manganese sulfate may be needed. Once sago palms have suffered from a manganese deficiency, half the initial rate should be applied yearly to prevent the deficiency from re-occurring.
Even though sago palms are not true palms – they are cycads – their nutritional needs are very similar to palms. Most of the time they grow well without any supplemental fertilization, but if they do need fertilizing, use a 8-2-12-4 (the fourth number is magnesium) palm fertilizer with micronutrients and avoid using other fertilizer products in their root zones.
For more information on sago palms please see:
Cycas revoluta, Sago Palm
by Matthew Orwat | Sep 16, 2013
Azaleas pruned late in the fall will have little or no bloom in the spring. 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 year because most bloom on previous years’ wood. 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.
Fall Pruned Azalea. Image Credit Matthew Orwat
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.
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 in a Minute.
by Matthew Orwat | Aug 19, 2013
Cercospora in Pepper
Image Credit Matthew Orwat
This summer’s rainy and humid weather has created a perfect environment for the proliferation of a variety of fungal diseases. In particular, Cercospora is a genus of fungus of which there are over 1,200 different species. Because there are so many species of this fungus, many different plant species are affected including many garden vegetables and ornamentals.
Cercospora leaf spot in Pepper
Image Credit Matthew Orwat
Cercospora causes purple, brown or black spots on a variety of garden vegetables and ornamental shrubs. The spots usually include a grey dead area in the center and a yellow “halo” or “ring” surrounding the entire spot. This disease usually starts at the base and interior of the plant, where there is more moisture and less air circulation, and moves outward.
Severe Cercospora infections have the ability to defoliate entire plants within a season and kill garden annuals, such as pepper, within a season. On shrubs, turf and perennials, Cercospora ranges from minor annoyance to major disease depending on the resistance of the cultivar or species. Serious infections can kill some ornamentals, such as Indian Hawthorn or Rose, in three years.
Several methods exist to limit the spread and severity of Cercospora outbreaks. It is a good practice to remove all dead plants and leaf litter from the garden. If Cercosproa infection occurs, remove and dispose of dead plants and pick up all leaf litter from the garden immediately upon drop. This will limit the fungal spore’s ability to reproduce. Another preventative strategy is to reduce water splash on leaves. Splashing water spreads Cercospora spores and allows them to take hold on a leaf. Irrigate the vegetable garden or landscape with drip irrigation to avoid wet leaves. Additionally, irrigate in the morning, so plants will not remain wet overnight. Cercospora requires 16 hours of moisture to reproduce. Specifically, infection of Indian Hawthorn has proven to be reduced by switching from overhead to drip irrigation.
Cercospora Infection on Rose
Image Credit U-Scout (Mathews Paret)
If fungicides must be used, be sure to follow label directions since some products labeled for the home ornamental garden, such as Chlorothalonil, are not labeled for turf. Be sure to use fungicides with more than one mode of action, since resistance may develop if only one type of fungicide is used.
For more information, please consult the following UF / IFAS publications regarding Cercospora:
Also, contact your County Extension Office for additional assistance.
by Gary Knox | Jul 29, 2013
Crapemyrtle flowering has been spectacular this year!
While most other garden plants droop from summer’s heat, humidity and heavy rains, crapemyrtle thrives and puts on an outstanding show of flowers all summer and fall. Thanks to modern breeders, there are all sizes of improved hybrid crapemyrtles with flower colors of lavender, purple, white, pink, or red.
Crapemyrtle Cultivar: ‘Tonto’
Image Credit: Gary Knox
Just say “No” to Pruning
- Crapemyrtle varieties come in tree-size, patio tree and shrub categories.
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Tree-size crapemyrtles grow 25 ft. tall and are ideal as flowering trees. Patio tree-form plants (up to 12 ft.) are beautiful as small, flowering specimen plants near patios, walkways, and entrances. Shrub forms (up to 6 ft.) make excellent accents in a shrub border and smaller types are effective as large groundcovers or container plants.
Crapemyrtle Cultivar: ‘Red Rocket’
Image Credit: Gary Knox
- Make sure you buy the right size crapemyrtle for your home. Don’t make the mistake of planting a tree-size crapemyrtle in an area too small for its ultimate size, or you’ll find yourself pruning it hard – and often – to keep it from out-growing its place.
Crapemyrtle Cultivar: ‘Sioux’
Image Credit: Gary Knox
Recommended Varieties
- Some of the best tree-size (25 ft.) types are Natchez (white), Red Rocket® (red), Sioux (pink) and Apalachee (lavender). Superior patio tree crapemyrtles (12 ft.) are Acoma (white), Cheyenne (true red), Tonto (fuchsia red), Hopi (pink) and Catawba (purple). Smaller shrub (6 ft.) crapemyrtles are hard to find, but Cherry Dazzle® is a nice mounding red and Pixie White and New Orleans (purple) are good selections.
Planting and Garden Care
- When it comes to planting, crapemyrtle is very tolerant and forgiving with three exceptions. First, crapemyrtle needs sun to flower freely, so plant it in a site receiving at least six hours of direct sunlight each day. Secondly, crapemyrtle will not grow in wet soils. Finally, never plant crapemyrtle too deep — if you do so, it will punish you by not flowering for years and years. Planting too deep literally smothers the roots, requiring the crapemyrtle to regenerate a new root system in the soil above.
- Crapemyrtle is very drought tolerant and almost seems to thrive on neglect. On the other hand, regular watering and fertilizer will help crapemyrtle grow faster and bigger.
Crapemyrtle Cultivar: ‘Acoma’
Image Credit: Gary Knox
More Beauty on the Way!
- Breeders are continuing to improve and introduce new crapemyrtles. Many new varieties were released in the last couple years. In particular, watch for new types with purple-burgundy leaf color all summer long! Time will tell which new ones grow best in Northwest Florida. Stay tuned as the world of crapemyrtle continues to evolve and improve!
*Gary Knox is Professor of Environmental Horticulture with the University of Florida. He is stationed at the North Florida Research and Education Center in Quincy, where he evaluates more than 100 cultivars of crapemyrtle.
by Julie McConnell | Jul 1, 2013
Blueberries
Have you tasted the great local blueberries available this season? Want to start your own Blueberry garden? Now that Blueberry harvest is in full swing in the Florida Panhandle, it is a good time to discuss blueberry culture.
Blueberry plants in garden centers lure us in with bell shaped flowers or especially if already setting fruit. Before you take one home, make sure your site is suitable. Doing your homework before you plant is important, but especially so when you want to grow a plant with specific cultural requirements such as blueberries. Blueberries require well-drained acidic soil that contains organic matter, a minimum of 4-5 hours of sunlight daily, and space away from competing roots. Chill hour requirements and bloom time vary by blueberry types.
Soil in the Florida Panhandle has a wide pH range (measure of acidity) and can vary greatly even within a half-acre site. Having your soil tested prior to planting is critical to growing blueberries successfully because it is very difficult to lower pH if your soil is higher than the target range. Blueberries need acidic soil (pH 4.2-5.5) to be able to use micro-elements in the soil such as iron and zinc. As the pH increases, these nutrients become less available to the plant even if they are present in the soil in adequate quantities. Nutrient deficiency leads to weak plants and loss of vigor. Plan to test your soil before you purchase plants to ensure your site has the ideal pH range, visit your local UF/IFAS County Extension Office to obtain a soil test kit. For more details about how soil pH affects your landscape, please see EDIS SL256: Soil pH and the Home Landscape or Garden.
Sandy soils commonly found in North Florida tend to be low in organic matter. Incorporating soil amendments directly into planting beds or using mulches that decompose (such as pinestraw or wood mulch) will help increase organic matter in your landscape. Peat moss or pine bark can be incorporated into beds planned for blueberries or pine bark can be used as mulch. Adding organic matter will help retain soil moisture, which is beneficial to blueberries that have shallow root systems.
Retaining soil moisture is valuable to blueberries, however, the site does need to drain well to a minimum depth of 18 inches. Areas that remain wet for long periods of time increase the risk of Phytophthora root rot damage. If an otherwise ideal site does not drain well, consider building a raised bed or changing the location.
Four to five hours a day is the minimum sunlight needed for good blueberry production. Make sure your sunny site is at least 20 feet from building foundations and competing tree roots. Blueberry plants can get large, over ten feet in height and width! Plan to give them room to grow; with pruning they can be maintained around 7’x7’.
There are two main types of blueberries that grow well in Florida: the southern highbush and rabbiteye. Among those types, there are specific cultivars with low chill requirements that perform better in Florida than in other southern states. Rabbiteye blueberries are recommended for areas north of Ocala, southern highbush for central and south Florida. When choosing cultivars, you need to plant at least two different cultivars within the same type (rabbiteye with rabbiteye) and make sure that bloom time overlaps so that cross pollination can take place.
Rabbiteye cultivars recommended for the Panhandle are:
Early season
• ‘Beckyblue’
• ‘Bonita’
• ‘Climax’
Mid- to late-season
• ‘Brightwell’
• ‘Powderblue’
• ‘Tifblue’
• ‘Woodard’
• ‘Chaucer’
• ‘Bluegem’
For more information about blueberry site preparation, selection, pest management, and care please see EDIS CIR1192 Blueberry Gardener’s Guide.
by | Jul 1, 2013
This summer parts of the Florida Panhandle have been blessed with ample rain, but coupled with high temperatures, this can be both a blessing and a curse.
Adequate moisture is critically important to landscape plants during hot weather, but too much rain or excessive watering also can bring problems. Wet soil combined with high temperatures can create stressful conditions for bedding plants, vegetables, shrubs and even trees – especially those just planted this year.
When the soil is saturated with water, pore spaces in the soil, which normally hold air, are filled with water. Since the roots of plants get the oxygen they need from the air in those spaces, the roots can literally drown in a soil that stays waterlogged over an extended period.
In turn, a sick root system leads to a sick plant. Plants in such situations often lose vigor, look wilted, turn yellow, are stunted and often die.
Symptoms of Root Rot on Azalea
Wet soil conditions also encourage fungus organisms that live in the soil to attack the roots or crown of a plant, thus causing rot. The crown is the area where the stem of a plant enters the soil. These disease organisms can cause die-back, inflict severe damage or even kill plants. Worse yet, once infection occurs, little can be done to help a plant affected by these disease organisms.
Plants with succulent stems such as impatiens and begonias, those that like cooler temperatures such as geraniums and dianthus and those that prefer drier, well-drained soils such as Indian Hawthorns are particularly susceptible.
Gardeners can take steps to help alleviate the situation. First , it is critical to adjust irrigation systems that are on automatic timers. Often seen are sprinklers unnecessarily watering at homes or businesses the day after or during a heavy rain simply because the timer turned them on. Turn off the automatic timer if the weather is wet, and turn the system on only when drier conditions occur.
Home Irrigation Timer
Beds should always be well mulched, at 2-4 inches, to control weeds and maintain soil moisture. If garden beds are staying too wet, however, the mulch can be pulled back from around plants or removed entirely to allow the soil to dry faster. Just make sure keep weeds are kept under control while the mulch is off.
Plants affected by wet soils or root rot may look wilted even though the soil is moist. A plant showing these symptoms immediately after a period of prolonged heavy rain may benefit from soil aeration in its root zone. Using a garden fork by driving the tines straight down into the soil and pulling straight out in numerous places around the plant is helpful. This provides air to the roots and encourages the soil to dry faster. Just be sure you don’t dig with the fork.
Gardening Fork
Fungal diseases that attack the foliage of many plants also are encouraged by rainy weather. Black spot on roses is prevalent even on fairly resistant varieties, and control is nearly impossible if it rains every afternoon. Cercospora leaf spot and Powdery mildew on crape myrtles can cause the leaves to turn yellow or red and drop off. The disease is not fatal, and the trees will recover without sprays, but flowering may be diminished.
Powdery Mildew on Crape Myrtle
Cercospora Leaf Spot on Crape Myrtle
Other pests such as snails and slugs thrive and reproduce rapidly during rainy weather. These pesky critters chew holes in the leaves and flowers of plants and are particularly fond of soft-leaved plants such as impatiens, begonias and hostas. Try not to let their populations get out of control. Note that Toads should be left alone because they feed on slugs. There also are numerous baits on the market that will help control snails and slugs. You can even place a bowl up to its rim in the ground and fill it half full of beer to attract and drown many snails and slugs.
Frequent rains can leach available nutrients from the soil in the landscape. Landscape plantings should be evaluated with this in mind and be fertilized, if needed. If possible, controlled release fertilizer should be used in this situation. Plants rapidly growing now such as lawn grasses, summer bedding plants and tropicals like ginger and hibiscus are especially vulnerable.
