Archive for January, 2012

Urban Forestry Grant Awarded to Palm Beach County

Urban Forestry Education <UF Laura Sanagorski>

Palm Beach County Cooperative Extension Service would like to thank the Florida Department of Agriculture and Consumer Services and the Florida Forest Service for their award through the 2011 National Urban and Community Forestry Grant Program. This grant will support a project entitled ” Strengthening our Urban Forest Through Education”.  This project will support arboricultural training for professionals, residents, and Master Gardener volunteers, as well as the creation of electronic learning modules available to all for free.

We look forward to implementing this project and give a special thanks to Mr. Adam Putnam, Commissioner of Agriculture, Mr. James Karels, Director of Florida Forest Services, and Mr. Charlie Marcus, Urban Forestry Director of Florida Forest Services.

2012 USDA Plant Hardiness Map

The USDA has released its 2012 plant hardiness zone map.  Palm Beach horticultural professionals will note that more of our county is now considered 10b than before.

Downy Mildew on Impatiens

Discolored upper leaf surface and downy mildew growth on lower leaf surface. <UF Laura Sanagorski>

updated 1/31/2012

Laura Sanagorski, Environmental Horticulture Extension Agent

Bill Schall, Commercial Horticulture Extension Agent

Downy mildew on impatiens is currently a concern in Palm Beach County.  High humidity paired with cool nights created the perfect conditions for disease development.  Downy mildews are caused by a variety of pathogens that tend to be specific to hosts; however Plasmopara obducens is the one that affects impatiens.  Some literature indicates that downy mildew favors about 50 – 72 degrees Fahrenheit nighttime temperatures.

HOSTS – Downy mildew affects all hybrids and varieties of Impatiens walleriana, also called Busy Lizzy.  New Guinea impatiens, Impatiens X hawkeri, is considered very tolerant.  Counties adjacent to Palm Beach County have reported less severe outbreaks in 2011 and early 2012.

Symptoms of downy mildew showing first on newer growth: leaf edges curling downward <UF Laura Sanagorski>

SYMPTOMS – Young plants and new growth are most susceptible and may show symptoms first.  Initially, leaves may look a little yellowish or speckled.  In fact, these symptoms look very similar to nutritional deficiencies.  You may see faint gray lines on the tops of leaves or notice leaf edges curling downward.  Sometimes the yellowing is not visible before leaf curling begins.

As the disease continues to progress, whitish downy looking growth will be visible on undersides of leaves. This whitish growth is spore-containing structures that have emerged from the lower leaf pores (stomata). Next, leaves and flowers will drop quickly, leaving mostly stems.

Continue reading

Reclaimed Water May Affect Fertilization Needs

Reclaimed water is being used more frequently in the landscape.  It’s important to remember that reclaimed water has different properties than drinking water processed by our local water plants.  While it is perfectly safe to use, reclaimed water can have a higher salt and nutrient content than rainwater or drinking water.  If a property you maintain uses reclaimed water as its irrigation source, you should manage the landscape a bit differently.  Most importantly, you’ll want to test the water or otherwise obtain current test results so you know what level of salt and nutrients is being applied in the landscape.

From a landscape perspective, the most important item of interest is the Continue reading

Josephiella Wasp Galls on Ficus


Wasp galls on Ficus microcarpa caused by Josephiella microcarpae. Upper leaf surface. <UF Laura Sanagorski>

Here’s another Ficus pest that likes our Cuban Laurels.  These galls are caused by the Josephiella wasp (Josephiella microcarpae).  This wasp was first identified in Hawaii in the late 1980’s (read here: A new species of Josephiella (Hymenoptera Agaonidae) forming leaf galls) and then in Florida in 2007.  Most often, galls are merely aesthetic issues, such as in the case of the harmless  Sea Grape Blister Galls.  In general, leaf galls are less damaging to trees and plants than stem galls.  This gall caused by the Josephiella wasp, can cause defoliation of Ficus plants and trees, so treatment may be necessary, especially if this pest is present in combination with Ficus Whitefly or other types of stress.  Systemic insecticides may be helpful in managing this gall-forming wasp.  Neonicotinoids have been used for gall insects but there is no documentation on its use for this insect.  Imidacloprid is one possible suggestion for treatment.  Remember that treatment for gall-makers will not get rid of the galls.

Wasp galls on Ficus microcarpa caused by Josephiella microcarpae. Lower leaf surface. Look closely for exit holes caused by emerging adults. <UF Laura Sanagorski>

The Josephiella adult female lays her eggs in Ficus leaf tissue; immature wasps feed on a leaf’s nutrients, causing swelling in the leaf tissue.  When the adults emerge, they leave tiny holes on the undersides of leaves.  Dr. Doug Caldwell, Commercial Landscape Horticulture educator with UF / IFAS Extension in Collier County, wrote an excellent article, Ficus Trees Under Attack!, about this and other Ficus disorders. 

If you see signs of this gall wasp on your customers’ ficus hedges and trees, you may not need to treat, but its good to know what you’re dealing with.

Palm Management in the Florida Landscape: February 28 & 29

If you haven’t yet attended “Palm School”, this is a valuable, condensed educational opportunity.  I highly recommend it for all horticultural professionals who manage palms in the landscape.

Date:  February 28-29, 2012 (2 days – Tuesday and Wednesday)

Time:  7:45 AM – 5:00 PM each day

Location:   University of Florida – IFAS Fort Lauderdale Research and Education Center

Reservations/Payment:  $300 by February 14, 2012 (or until class fills up)

CEUs requested:  ISA, LIAF, FNGLA and FDACS (pesticide license)

Classroom and Field Topics: Ÿ Diagnosing Palm Problems, Palm Insects, Palm Anatomy and Growth,  Palm Diseases,  Physiological Disorders,  Normal Abnormalities, Nutrient Deficiencies,  Fertilizer Formulations, Sampling and Leaf Analysis,  Fertilizer Application Techniques,  Transplant Issues,  Pruning Palms

For more information and to reserve your spot for “Palm School”, download the pdf brochure (Palm Management Training – Feb2012) or contact: Dr. Monica Elliott ; phone:  954/577-6315

A Beneficial Insect to Papaya

Have you seen this cottony-looking mass on papaya trees in the landscape?  This mass is composed of the cocoons of braconid wasp larvae that emerged from one of the large sphinx moth caterpillars (hornworms) that feed on papaya.  Hornworms can be very damaging to papaya, so it’s a great sign when we see signs of this wasp.  Most likely, the hormworm that was attacked in this case is the juvenile ello sphinx moth, Erinnyis ello.

Papaya Beneficial insect: Brachonid wasp cocoons. You can see the hormworn's previous location in the center of the cottony mass. Look closely for emerging adult wasps. *click for detail* UF Laura Sanagorski

A few weeks ago I wrote about another beneficial Braconid wasp that attacks the tomato hornworm.  The lifecycle and mechanism of control for this one is similar.  The wasp lays its eggs just under the skin of the hormworm. When larvae emerge from the eggs, they begin feeding on the insides of the still-living hormworm. When the juvenile wasps have matured, they eat through the skin of the hornworm, and spin their cocoons, after which the hornworm will die.  Adult braconid wasps will then seek out other hormworms to attack.  The difference between this braconid wasp and some others is that the host hornworm is gone here, whereas in other cases we find it still intact.

The Braconid family is made up of over 1000 species of tiny wasps that pose no threat to humans.  Insects in this family act as parasitoids to control pest insects, including a number of harmful caterpillars, aphids, and other landscape pests.  These beneficial insects are another good reason to use pesticides responsibly in the landscape and to spot-treat when possible.