Gardening In The Panhandle

Small Cockroaches Flying Into Homes

Figure 1. Adult female Asian cockroach, Blattella asahinai Mizukubo, carrying an egg case (ootheca). Photograph by R.W. Baldwin, University of Florida.

The Asian cockroach was first identified as a newly introduced species in the U.S. in Lakeland, Florida in 1986. I started seeing this small cockroach in our area about 17 or 18 years ago. They’ve done well recently with the rains and their numbers are probably higher now as a result. They prefer warm, wet conditions. Populations of 30,000 to 250,000 per acre are reported in some literature.

They are mostly active at night, hiding in mulched landscape beds and lawns during the day. It’s not uncommon to disturb them as you walk through or hand water mulched plant beds during daytime hours. When doing so, the little roaches, which may be mistaken for small moths, quickly fly as they are disturbed.

Asian cockroaches occasionally fly into homes or automobiles at night, attracted to lights. Thankfully, they don’t live long indoors, though.

Control is difficult. Because they can fly 120 feet or more in a single flight, large areas around a home require treatment. And cockroaches in surrounding untreated areas (lawns, mulched plant beds and nearby woods) may result in re-infestation.

Traditional indoor treatments are ineffective because Asian roaches don’t typically live and breed indoors. The best control has been attained by using insecticide baits (labeled for roach control) in infested areas outdoors. Always follow the label directions and precautions when using any pesticide, including insecticides.

Sodium vapor lamps for outdoor lighting and yellow incandescent bulbs for porch lighting are less attractive to the flying adults.

Both the German and Asian cockroach adults are about 5/8 inch long and are brown to dark brown in color with two darker parallel bands running lengthwise just behind their head. But unlike the German cockroach, the Asian cockroach is a strong flier. Even though German cockroaches have wings, they do not fly. Also, unlike the German cockroach, which prefers to live indoors and is a major household pest as a result, the Asian cockroach prefers to live outside.

For more info on this roach species, visit the below UF/IFAS Extension EDIS website.

http://edis.ifas.ufl.edu/in277

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Author: Larry Williams – llw5479@ufl.edu

Larry Williams is the County Extension Director and Residential Horticulture Agent for the UF/IFAS Extension Office in Okaloosa County.

Larry Williams

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/07/22/small-cockroaches-flying-into-homes/

The Grass is Getting “Hungry”

The Grass is Getting “Hungry”

(UF/IFAS photo Thomas Wright)

Northwest Florida’s weather patterns can present challenges to maintaining a health lawn. Heavy rains promote fast growth and relentless sunshine causes lawns to fade.  In the last 200 days we have received at least 68 days of rain.  While the rest of Florida was experiencing record drought, the Panhandle was experiencing torrential downpours.  With every drop of rain your spring fertilizer is being metabolized by the lawn, reducing how many nutrients remain in the soil.  Even the best slow-release fertilizer will only last 3-4 months.  The message is: “It’s time for more fertilizer.”

A healthy lawn is an important component of the urban landscape. Not only do lawns increase the value of a property, they also reduce soil erosion, filter stormwater runoff, cool the air, and reduce glare and noise.  A healthy lawn effectively filters and traps sediment and pollutants that could otherwise contaminate surface waters and groundwater.  Lawns require nutrients throughout the growing season to stay healthy.  In Northwest Florida the growing season is typically April to October.

Proper fertilization consists of selecting the right type of fertilizer and applying it at the right time and in the right amount for maximum plant uptake. The type of fertilizer should be based on a soil test, available through UF/IFAS Extension. The timing of application and amount of fertilizer is dependent on the research-based recommendations for the grass species and the fertilizer analysis of the product being used.

Chart excerpted from Florida Friendly Landscaping publication

Select only a fertilizer that states that the product is for use on residential turf. Do not use a fertilizer meant for flower or vegetable gardens on lawns. By Florida Administrative Code, Rule 5E-1.003, the Urban Turf Rule requires that the fertilizers being applied to residential lawns are labeled for the site and the application rates be followed.  Typically, these products will contain both slow-release nitrogen and low or no phosphorus.  Slow-release nitrogen will provide a longer-lasting response from the grass and reduces the potential for burning. For more information on the Urban Turf Rule go to: http://www.edis.ifas.ufl.edu/pdffiles/EP/EP35300.pdf.

With frequent rain the soil is also losing iron. Keep in mind that the green fading to yellow appearance in your lawn may be an iron deficiency.  Before applying your summer fertilizer put out a liquid chelated iron.  It will improve the health of the lawn while you are trying to find a dry day to fertilize.  While it is necessary to water in fertilizer with ¼” of water to reduce burn potential and volatilization, never apply fertilizer when heavy rain is expected.  The rainfall over ¼” can encourage runoff and/or leaching of that fertilizer, which can be costly and environmentally harmful.

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Author: Sheila Dunning – sdunning@ufl.edu


http://okaloosa.ifas.ufl.edu

Sheila Dunning

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/07/22/the-grass-is-getting-hungry/

Mowing Your Lawn Correctly

Mowing Your Lawn Correctly

Northwest Florida has experienced an enormous amount of rain this summer. The western panhandle has received over 29 inches of rain since the beginning of May according to the Florida Automated Weather Network station at the West Florida Research and Education Center in Jay, Florida. That is 44% of average annual rainfall in less than two months. All of this rain has probably thrown off the normal lawn mowing routine. It is hard to get out and mow the lawn when its pouring buckets or the lawn resembles a swamp. With all of this in mind, there are a couple of mowing pointers that would be useful to implement to address the out of control lawn growth and the challenges posed by not being able to stick to normal mowing schedule.

  • Always attempt to mow at the IFAS recommended height for your species of turfgrass. The recommended heights are determined by how quickly the species grow in our climate. The chart below shows the best heights at which to mow your lawn. The fine textured zoysiagrasses are not listed but should be mowed at 0.5 to 1.5 inches. Check the lawn mowers mowing height by measuring the distance from the ground to the bottom of the mowing deck on a flat surface.

From Mowing Your Florida Lawn: http://edis.ifas.ufl.edu/pdffiles/LH/LH02800.pdf

  •  When you do get out to mow, never remove more than 1/3 of the leaf blade. If you cut to short you will “scalp” the turf and cause a brown look on the lawn. This can be damaging to the turf and allow for weeds to get established by exposing the soil to the sunlight. What is taking place more in northwest Florida is not mowing frequently enough and cutting off excess growth due to the rain. This also can cause scalping so it is very important to mow frequently enough to only remove 1/3 of the leaf blade.

A zoysia lawn that has been “scalped” after excess growth and infrequent mowing. (Photo Credit: Blake Thaxton)

Other practices such as keeping your mower blade sharp, mowing in different directions, and leaving clippings on the ground will help keep a healthy Florida lawn. Please see more information about mowing correctly in Florida in the University of Florida/IFAS Extension publication: Mowing Your Florida Lawn

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Author: Blake Thaxton – bthaxton@ufl.edu

Santa Rosa County Extension Agent I, Commercial Horticulture

Blake Thaxton

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/07/21/mowing-your-lawn-correctly/

The Predatory Praying Mantis

The Predatory Praying Mantis

 

Praying Mantis, Image Credit Les Harrison

Summertime is bug time in the Florid Panhandle.  The weather has provided enough rain for the bugs which depend on a supply of foliage and the temperatures have been ideal for a population explosion.

Stink bugs, leaf-footed bugs, grasshoppers, all sizes and colors of caterpillars and many more have been enjoying the lush and plentiful dining options.  More than one Panhandle homeowner or gardener has been plagued by the sudden appearance of a hoard of hungry nuisances which are eyeing the menu choices at residences.

Fortunately, nature has a way of eventually balancing all situations when left to its own devices. With the increase of the plant eaters comes a surge in those insects which restrain the excess population.

One of the most easily recognized predator insects is the praying mantis.  This beneficial insect is actually a family with multiple members, some of which have been introduced to Florida.

While there are over 2400 mantis members worldwide, Florida is home to eleven. Two of those exotics have been introduced from other regions, but considered non- invasive.

Mantises are thought to have evolved during the Cretaceous period about 100 million years ago, possibly from a predatory cockroach with similar front legs. Their closest surviving insect relatives are cockroaches and termites, both of which they will consume if given the opportunity.

Like many insects, the mantis is equipped with a tough, durable exoskeleton which provides a basis for successful close quarter combat and meal procurement. These hunters have three other advantages which create a severe vulnerability in their prey’s defense and potential for surviving a mantis encounter.

The mantis is an ambush predator which will lay in wait for the victim/meal to deliver itself.  The mantis has the instinctive ability to identify and hide in areas with high amounts of prey species traffic.

This insect is a master at stealth and camouflage. The creature’s coloration and linear shape allow it to blend into the earth tones of many settings.

To complement its ability to conceal itself in plain sight, the mantis can hold perfectly still and patiently wait for the oblivious bug to bumble into sticking range.  At that precise moment, the mantis is a blur of lethal motion.

The mantis’ forelimbs are a set of deadly spiked vices used to immobilize and secure its target.  It extends these spiny levers forward in a raised position which appears as though it is in a mealtime prayer, hence its name.

The kill technique is to impale and restrain the victim with a single stroke of the forelimbs while holding the victim securely to the mantis’ body.  On occasion the attempt fails and the mantis has to apply a more direct approach.

This insect’s beak is designed for slicing and tearing its victim’s body. Its jaw muscles provide the power to effectively employ this tool.

Depending on its stage of live, the mantis will eat a wide variety of creatures.  Early stage mantises will eat little flies and other tiny insect (including its siblings), but at maturity they will take on small reptiles and amphibians along with a variety of destructive insects.

Female mantises will even consume their prospective mates. Despite its vicious and cannibalistic nature, the praying mantis is the answer to many gardeners’ prayers.

To learn more about praying mantises and other beneficial insects, check out this EDIS site with many articles on various species of beneficial insects.

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Author: Les Harrison – harrisog@ufl.edu

Les Harrison is the UF/IFAS Wakulla County Extension Director, Agriculture and Natural Resources. He works with small and medium sized producers in the Big Bend region of north Florida on a wide range of topics. He has a Master’s of Science Degree in Agricultural Economics from Auburn University and a Bachelor of Science Degree in Journalism from the University of Florida.

Les Harrison

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/07/14/the-predatory-praying-mantis/

Ponder the Antiquity of Fruits and Vegetables

Ponder the Antiquity of Fruits and Vegetables

The modern carrot is available in many sizes, colors, and flavor profiles thanks to thousands of years of plant breeding. Photo by Kelly Thomas.

Fruits and vegetables have undergone various forms of domestication for thousands of years. Throughout this time, selective breeding of wild forages has allowed humans to develop crops with many desirable traits, such as increased size, higher sugar content, more nutrition, and brighter colors.

If you ate a carrot 5,000 years ago, you would be in for a surprise. First, it would not be orange. Instead, it would be white or purple, and would taste very bitter and be very small. We think wild carrots were first cultivated around 1,100 years ago, but that it took another 600 years to develop carrots that are not only available in white and purple, but also yellow, orange, and even red.

Sweet corn 9,000 years ago was a thousand times smaller, and barely edible, tasting more like a raw dried potato than corn, with only a few hard kernels per ear.

When you trace back the history of fruits and vegetables, you not only see many changes taking place through human intervention, but also many rituals, beliefs, and superstitions along the way. Take the mighty onion, for example. Did you know that Greek athletes in the Ancient Olympic Games would eat pounds of raw onion, drink the juice of onions, and rub onions all over their bodies before competing?

Roman generals believed garlic gave soldiers courage and strength, so they planted whole fields of it in areas they conquered, believing this transferred bravery to the armies. According to ancient Egyptian records, the Pharaoh gave the Egyptian slaves who built the pyramids garlic daily, along with their meager rations of beer and flat bread, as a means to increase strength and endurance. By today’s standards, it is believed it cost the Pharaoh two million dollars to keep the slaves supplied with garlic.

The Aztecs domesticated tomatoes around 500 BC, but they were not introduced to Italy until the 16th century. Even then, it took Italians another 250 years to embrace the tomato, as this member of the nightshade family was – understandably – feared to be poisonous. Can you imagine your pizzas and spaghetti without marinara?

Cucumbers originated in India, where their domestication started more than 4,000 years ago. They were traded to the Middle East and Europe about 3,000 years ago, and were even mentioned in the Epic of Gilgamesh. In Ancient Rome, Emperor Tiberius, who reigned briefly from 14 to 16 AD, demanded that he be served cucumbers daily. In the winter, his gardeners had to grow cucumbers in mobile wooden frames to protect the plants and expose them to the sun.

So the next time you enjoy the crunch of a bright orange carrot, sink your teeth into a chunk of hot garlic bread, or nurture your prized heirloom tomatoes, reflect back on just what it took our ancestors to get to the fruits and vegetables we relish today.

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Author: Molly Jameson – mjameson@ufl.edu

Molly Jameson

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/07/12/ponder-the-antiquity-of-fruits-and-vegetables/

Why Don’t My Plants Match?

Why Don’t My Plants Match?

Coontie (Zamia floridana) planted at the same time but growing at different rates. Photo: J_McConnell, UF/IFAS

When designing landscapes, it is popular to create lines and masses of plants for high visual impacts. Plants are carefully selected to be similar in size and shape at the time of installation. They are all grouped together, so they must be getting the same care, but why do they look different years later? There are several factors to consider when we are trying to figure out why a perfectly matched set no longer looks like a uniform planting.

Although plants may be in the same bed, shadows cast at certain times of the day may reduce sunlight to some sections and not others. This can be caused by structures or trees that have grown over time and changed light patterns.

Supplemental irrigation may also be variable even with the best system design. Over time plants grow and may block sprinkler emitters from reaching some sections of landscape beds. Even if the landscape relies on natural rainfall, there can be still be dry/wet spots in the landscape due to drainage off of hard structures, low areas, or wind direction during storms.

It might be possible to adjust some lighting and watering issues, but there is one factor that many gardeners have not considered – genetics. If plants were grown from seed, than variation is not only possible, but likely. This might be displayed as differences in height and width, foliage color, flower color, speed of growth – all may be influenced by parentage despite best efforts to care for each plant similarly.

Many landscape plants are cultivars. This means they are grown from cuttings or divisions which make them identical to the original plant. When a plant is grown from seed, however, there is no guarantee it will have the same specific qualities as the mother plant.

To combat this phenomenon, landscapers should check sunlight and watering for irregular growth patterns and adjust if needed. If a landscape design requires uniform plants, use named cultivars rather than seedling grown plants in lines or masses.

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Author: Julie McConnell – juliebmcconnell@ufl.edu

UF/IFAS Bay County Horticulture Extension Agent I

Julie McConnell

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/07/12/why-dont-my-plants-match/

Four Must-Have Native Perennials for Summer!

Four Must-Have Native Perennials for Summer!

Let’s be honest with each other and have a moment of transparency, one gardener to another. Even though we are plant people, most of us get a lot less enthusiastic once the mercury explodes over 90 degrees each June. All the things that were fun in the spring (watering our favorite fickle plants, deadheading spent flowers, staking, tying, fertilizing, the list goes on) have ceased to be fun.  At this point, like a baby bird pushed out of the nest, the plants in our yards have to either fly or die.  Fortunately, if we select the correct, tough-as-nails plants to start with, our gardens do not have to decline when we retreat into the air conditioning!  The following are four of my favorite ironclad native perennials that will reward you with color, texture, and overall excellent performance all summer and ask very little in return!

Black-Eyed Susan ‘Goldsturm’ (Rudbeckia fulgida var. sullivanti ‘Goldsturm’)

There is no more reliable plant in the garden than plain old Black-Eyed Susan. This beauty delivers yellow-gold flowers with its namesake black, cone-like centers perpetually from May to frost in the Panhandle and returns like clockwork each spring to do it all over again! While not exactly native, the 1937 selection ‘Goldsturm’ is still easily the most popular Rudbeckia eighty years later, with good reason.  ‘Goldsturm’ improves upon the native Rudbeckias in almost every way.  It is a more compact plant, forming a spreading mass of flowers about two feet in height, sports larger, showier flowers than the species, and flaunts lustrous dark green foliage.  If low-maintenance, raw flower power is what you are after, Black-Eyed Susan ‘Goldsturm’ is right for you!

If the landscape calls for a plant with flowers hotter than the July sun, Scarlet Sage is hard to beat! This tough, prolific perennial boasts fire engine red, tubular-shaped flowers throughout the warm season in Northwest Florida and is one of the very best attractors of a host of pollinators including butterflies and hummingbirds. Growing this native couldn’t be easier, it is not picky about soil type and texture so long as it doesn’t stay waterlogged, it requires little to no supplemental fertilizer or water, and will thrive in full sun or partial shade.  A word of warning before planting Scarlet Sage however, be aware that the plant will self-sow prolifically, potentially appearing in unwanted places and becoming a nuisance.  Though with a plant this undemanding and pretty, I do not mind one bit if it decides to ramble through the landscape.

Scarlet Sage (Salvia coccinea)

Carolina Petunia (Ruellia caroliniensis) (note: Not to be confused with Mexican Petunia (Ruellia simplex), which, despite its popularity, is an invasive weed and should not be planted)

For those of you that lament hot weather because it means the decline of the showy annual petunias sold by the thousands at big box stores across the South, there is a summer solution for you! Carolina Petunia is a compact (growing to 24” in height), hardy plant whose many outstanding ornamental qualities, including soft purple flowers produced in profusion, make it a great addition to virtually any garden border.  It is not picky regarding soil and while flowering is best in full sun, it grows just fine in the dappled shade of pines or other taller perennials and shrubs.  Like Scarlet Sage, Carolina Petunia will seed around in the landscape but is easily managed and never wears out its welcome.

Dwarf Fakahatchee Grass (Tripsacum floridanum)

 

 

 

 

 

 

 

Ornamental grasses have gained in popularity over the last few years and with good reason! Ornamental grasses tend to be drought tolerant, laugh at the summer sun, and require little maintenance.  However, many popular ornamental grass species like Miscanthus, Muhlenbergia, Pennisetum, and others tend to grow too large for most gardens and end up being replaced a few years later.  Dwarf Fakahatchee fits this niche perfectly, with its emerald green leaf blades only growing 2-3’ in height and width.  It is also more adaptable than most ornamental grass species as it will thrive in sun or partial shade and is tolerant of both wet and dry sites!  While it lacks the colorful flower panicles of Muhly Grass or Miscanthus, Dwarf Fakahatchee does possess interesting brown flower stalks and seed heads as well!

All of these awesome low-maintenance, native perennial selections can be purchased at member nurseries of FANN (Florida Association of Native Nurseries) or local independent garden centers. As always, if you have any questions about this or other horticultural topics, contact your local UF/IFAS County Extension Office.

 

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Author: Daniel J. Leonard – d.leonard@ufl.edu

Horticulture Agent, Walton County

Daniel J. Leonard

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/07/05/four-must-have-native-perennials-for-summer/

African Blue Basil: A Pollinator Favorite

African Blue Basil: A Pollinator Favorite

Many bees and beneficial wasps will be attracted to African blue basil. Photo by Beth Bolles, UF IFAS Extension Escambia County

Basil is a favorite plant in the summer herb garden and an absolute must for those who enjoy fresh leaves for a sandwich or delicious homemade pesto. While we grow basils as a food enhancer, an added benefit is that those basil selections that form flowers are very attractive to pollinators.  If you would rather not let your favorite basil form flowers, consider adding a specific species that is grown more for its attractiveness to pollinators than its culinary uses.

African blue basil is a hybrid of two basils that has inherited a camphor flavor from one of its parents. Although edible, the flavor may not be appealing to those who are familiar with more traditional basil flavors.  Plants produce abundant flowers that are pink with a dark purple base, although flowers are sterile so no seeds will be formed.  If you want more African blue basil, you must purchase transplants or start your own from cuttings off the main plants.

African blue basil enhances gardens and landscapes. Photo by Beth Bolles, UF IFAS Extension Escambia County

Flowers of African blue basil are also showy in the garden. Photo by Beth Bolles, UF IFAS Extension Escambia County

Like other basils, African blue basil does like soils amended with composts that are well-drained. Plants thrive in full sun and will form rounded mounds that will be much larger than more culinary basils, up to five feet in some gardens.  Plants do form woody stems and although frost tender, some plants may return in the spring in more protected areas.

Although some edible gardeners may not want to allow space for a basil that they will not use in the kitchen, the amount of pollinator activity on this selection makes it a benefit to any edible garden for all the frost-free months.

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Author: Beth Bolles – bbolles@ufl.edu

Horticulture Agent, Escambia County

Beth Bolles

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/07/05/african-blue-basil-a-pollinator-favorite/

Rain Gardens – A Solution for Runoff

Rain Gardens – A Solution for Runoff

This rain garden used stone for a berm and muhly grass as a decorative and functional plant. Photo credit, Jerry Patee

Tropical Storm Cindy’s early arrival soaked northwest Florida this month, followed by even more heavy rain. Homes in low areas and along the rivers flooded and suffered extensive damage. That being said, we are just entering our summer “rainy season,” so it may be wise to spend extra time thinking about adjusting your landscape to handle our typically heavy annual rainfall.

For example, if you have an area in your yard where water always runs after a storm (even a mild one) and washes out your property, you may want to consider a rain garden for that spot. Rain gardens are designed to temporarily hold rainwater and allow it to soak into the ground. However, they are quite different aesthetically from stormwater ponds, because they are planted with water-tolerant trees, shrubs, groundcovers and flowers to provide an attractive alternative to the eroding gully that once inhabited the area! Rain gardens are not “created wetlands,” but landscaped beds that can handle both wet and drier conditions. Many of the plants best suited for rain gardens are also attractive to wildlife, adding another element of beauty to the landscape.

A perfect spot for a rain garden might be downhill from a rain gutter, an area notorious for excess water and erosion. To build a rain garden, the rainwater leaving a particular part of the property (or rooftop), is directed into a gently sloping, 4”-8” deep depression in the ground, the back and sides of which are supported by a berm of earth. The rain garden serves as a catch basin for the water and is usually shaped like a semi-circle. The width of the rain garden depends on the slope and particular site conditions in each yard. Within the area, native plants are placed into loose, sandy soil and mulched.   Care should be taken to prevent the garden from having a very deep end where water pools, rather allowing water to spread evenly throughout the basin.

This larger rain garden, or bioretention area, functions as stormwater treatment for a large parking lot in North Carolina. Photo credit: Carrie Stevenson, UF / IFAS Extension

Besides reducing a problematic area of the lawn, a rain garden can play an important role in improving water quality. With increasing populations come more pavement, roads, and rooftops, which do almost nothing to absorb or treat stormwater, contributing to the problem. Vegetation and soil do a much better job at handling stormwater. Excess sediment, which can fill in streams and bays, and chemicals from fertilizers and pesticides are just some of the pollutants treated within a rain garden via the natural growth processes of the plants.

A handful of well-known plants that work great in rain gardens include: Louisiana iris, cinnamon fern, buttonbush, Virginia willow, black-eyed Susan, swamp lily, tulip poplar, oakleaf hydrangea, wax myrtle, Florida azalea, river birch, holly, and Southern magnolia. For a complete list of rain garden plants appropriate for our area, visit the “Rain Garden” section of Tallahassee’s “Think about Personal Pollution” website.

For design specifications on building a rain garden, visit the UF Green Building site or contact your local UF IFAS County Extension office.

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Author: Carrie Stevenson – ctsteven@ufl.edu

Coastal Sustainability Agent, Escambia County Extension

Carrie Stevenson

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/07/05/rain-gardens-a-solution-for-runoff/

Algal Leaf Spot Common on Magnolias and Camellias

Algal Leaf Spot Common on Magnolias and Camellias

Algal leaf spot, also known as green scurf, is commonly found on thick-leaved, evergreen trees and shrubs such as magnolias and camellias.  It is in the genus Cephaleuros and happens to be one of the only plant parasitic algae found in the United States.  Although commonly found on magnolias and camellias, algal leaf spot has a host range of more than 200 species including Indian hawthorn, holly, and even guava in tropical climates.  Algal leaf spot thrives in hot and humid conditions, so it can be found in the Florida Panhandle nearly year round and will be very prevalent after all the rain we’ve had lately.

Symptoms

Algal leaf spot is usually found on plant leaves, but it can also affect stems, branches, and fruit. The leaf spots are generally circular in shape with wavy or feathered edges and are raised from the leaf surface. The color of the spots ranges from light green to gray to brown.  In the summer, the spots will become more pronounced and reddish, spore-producing structures will develop. In severe cases, leaves will yellow and drop from the plant.

Algal Leaf Spot

Algal leaf spot on a camellia leaf. Photo Credit: University of Florida/IFAS Extension

The algae can move to the stems and branches in more extreme cases. The algae can infect the stems and branches by entering through a small crack or crevice in the bark. The bark in that area cracks as a canker forms that eventually can girdle the branch, killing it.

Algal Leaf Spot on a Stem

Algal leaf spot on a sycamore branch. (Platanus occidentalis). Photo Credit: Florida Division of Plant Industry Archive, Bugwood.org.

Management

In most cases, algal leaf spot is only an aesthetic issue. If only a few leaves are affected, then they can just be removed by hand.  \It is important that symptomatic leaves are discarded or composted offsite instead of being left in the mulched area around the trees or shrubs. If symptomatic leaves are left in the same general area then irrigation or rain water can splash the algal spores on healthy leaves and branches. Infected branches can also be removed and pruned.

Preventative measures are recommended for long-term management of algal leaf spot. Growing conditions can be improved by making sure that plants receive the recommended amount of sunlight, water, and fertilizer. Additionally, air circulation around affected plants can be increased by selectively pruning some branches and removing or thinning out nearby shrubs and trees. It is also important to avoid overhead irrigation whenever possible.

Fungicide application may be necessary in severe cases. Copper fungicides such as Southern Ag Liquid Copper Fungicide, Monterey Liqui-Cop Fungicide Concentrate, and Bonide Liquid Copper Fungicide are recommended. Copper may need to be sprayed every 2 weeks if wet conditions persist.

Algal leaf spot isn’t a major pathogen of shrubs and trees, but it can cause significant damage if left untreated. The first step to management is accurate identification of the problem.  If you have any uncertainty, feel free to contact your local Extension Office and ask for the Master Gardener Help Desk or your County Horticulture Agent.

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Author: Matt Lollar – mlollar@ufl.edu

Matt Lollar is the Jackson County Horticulture Agent. He has 5 years of experience with University of Florida/IFAS Extension and he began his career in Sanford, FL as the Seminole County Horticulture Agent. Matt is originally from Belle Fontaine, AL. He earned his MS and BS degrees in Horticulture Production from Auburn University.

Matt Lollar

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/06/29/algal-leaf-spot-common-on-magnolias-and-camellias/

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