Archive for November, 2011

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Sea Grape Blister Gall

You’re probably familiar with galls on Oaks and some other species. Galls are abnormal growths formed on plants as a result of insects’ egg-laying or feeding behaviors.  Most galls are not harmful to the plant (in fact we don’t even consider them pests), although they may be disturbing to your customers.

Sea Grape Blister Gall. UF Laura Sanagorski

This Sea Grape Blister Gall is caused by a midge (Ctenodactylomyia watsoni) , or a type of tiny fly.  Most gall midges prefer a specific species of plant, as in the case of this one, for which Sea Grape is the only host. The galls in this photo contain larval midges that have not yet hatched.  After they hatch, we will see a little hole in each gall where the larvae emerged.

If you notice Sea Grape Blister Gall on properties you manage, there is nothing you need to do.  This midge is not very prevalent in South Florida, and it causes very little damage.  If you do see these galls, it will only be on a few leaves here and there.  It’s definitely good to know what these interesting growths are!

Master Landscape Management 2012 ~ registration open

The 2012 Master Landscape Management Course schedule has been posted!  See the attached brochure for details. 2012 Master Landscape Management Brochure.

Master Landscape Management. UF Laura Sanagorski

The program is provided for all horticultural professionals.  FNGLA, LIAF, ISA, pesticide applicator, and CCA CEUs are being requested for the program.  Questions can be directed to Laura Sanagorski, Environmental Horticulture Extension Faculty, by e-mailing or calling 561.233.1748.

Soil Testing

Soil testing is the best way to determine the pH of  soil as well the nutritional content for properties that you care for.  This can be a way to troubleshoot problems in the landscape and can also be a value-added service to provide to your customers.

The University of Florida has soil testing labs and there are local ones as well.   We offer two types of test: one for soil pH and recommended liming requirements and one for pH plus soil nutrient availability of Phosphorus, Potassium, Calcium, and Magnesium.  The tests cost $3.00, and $7.00, respectively.  We don’t test for Nitrogen because this nutrient changes chemical forms rapidly in the landscape.

So why might you want to know the pH of the soil?  As pH levels become either more acid or more alkaline, nutrients in the soil become less available to our plants.  The nutrients may be there, but not in the chemical form that your plants can use.  Our pH in south Florida is typically on the high (alkaline) side.  Many of our landscape plants can tolerate a wide range of pH levels, but some are pickier.  Ixora is one example of a plant that is very sensitive to high pH levels. The red, splotchy discoloration on Ixora is the plant’s expression of Phosphorus and Potassium deficiency, induced by pH.

pH-induced Potassium and Phosphorus deficiency on Ixora. UF Laura Sanagorski

These two nutrients are most likely in the soil, but are not in a chemically available form at higher pH levels.  Your options in this case would be to either live with the deficiency or to reduce soil pH by applying sulfur or an amendment such as aluminum sulfate or ammonium sulfate.  However, the best outcome for this situation would have been to choose plants that are happy with the pH – the right plant, right place principle.

Many landscape plants are tolerant of a wide range of pH and nutrient levels.

Potassium deficiency. UF Laura Sanagorski

Palms are very sensitive to nutrient deficiencies.  Potassium (see photo on left) and Magnesium deficiencies are two nutrient problems to which our South Florida palms are very sensitive.  If a property you care for has a lot of palms or you are considering planting species that are sensitive to soil pH levels, you might want to recommend soil testing to your client.

To submit a sample to the University of Florida’s soil testing lab, you can either pick up a test kit here at the Palm Beach County extension office (531 N. Military Trail) or you can download the form at http://edis.ifas.ufl.edu/pdffiles/SS/SS18700.pdf .  This form gives detailed instructions on how to collect a sample.  When you receive you test results, in about a week, I’ll be happy to discuss the report with you.

Split Canopy on Date Palms

Split Canopy on Date Palm. UF Laura Sanagorski

I received a call about these Date Palms.  When we see older fronds drop like this, it is concerning, because older frond drop is a classic indicator of Lethal Yellowing (LY).  Fortunately, this isn’t LY.  The drop is pretty uniform around the trunks of the palms, so we can rule out wind damage (which has been very prevalent in eastern Palm Beach County recently).  Since the fruit are still attached, we can rule out LY.  If we saw palms that looked like these, and the dropped fronds were turning brown, paired with a sudden drop of the fruit, it would possible indicate LY.

Split Canopy on Date Palm. UF Laura Sanagorski

This look is referred to as “split canopy” and tends to occur when the Date Palm is fruiting.

We don’t have a full explanation of this, and it doesn’t happen to all fruiting Date Palms, but it may have to do with the weight of the fruit.

You can learn more about lethal yellowing through Dr. Nigel A. Harrison and Dr. Monica Elliott’s publication: Lethal Yellowing (LY) of Palm.

Florida-Friendly Fertilizing Cartoon

Please enjoy this cartoon about Florida-Friendly fertilizing!

Let us know what you think!

Wind Damage in the Landscape

I’ve gotten a lot of calls over the past few weeks about plants that are dying or burning up “suddenly” in the landscape.  The good news is that it is very likely wind damage.  If you remember, we had some incredibly windy days just over a month ago.   The persistent wind paired with salt spray off of the ocean caused salt and wind burning all over landscapes in Palm Beach County.  A lot of our landscape plants are just showing their stress now.  Most will recover quickly.  The telltale sign of the wind and salt damage we’re currently seeing is that the majority of the damage is on the portions of the plant exposed to the east.

Windburn on Jasmine. UF Laura Sanagorski

 The Jasmine, above, located on a property near the beach, is showing wind-burning on its eastern side.

UF Laura Sanagorski

The Beach Sunflower, above, is showing stress from the heavy winds a few weeks ago.  Beach Sunflower is a beach plant, and it is still susceptible to wind damage.

UF Laura Sanagorski

The Crown of Thorns, above, was partially defoliated by the winds.  

If you see signs like the ones above, don’t worry, its not a new disease- just a delayed response over some severe weather.  Keep plants healthy by ensuring that they aren’t over- or under- watered or fertilized, and minimize other stresses as much as possible, and they’ll be back to normal soon.