UF/IFAS Okeechobee County Extension Service

458 Highway 98 North

Okeechobee, FL 34972-2578

Phone: (863) 763-6469

E- mail:  dfculbert@ifas.ufl.edu

 

Sweep up Witch’s broom

 

A recent newsletter article came across my desk, along with a curious question in my phone message box.  The caller wanted to know why her old Oleander bush had these unusual tufts of growth that were turning brown.  It turns out that both the article and the call are concerned with the same condition: witch’s broom.

 

There are many unusual kinds of woody stem distortions that are called witches broom. When something causes the growing tip to die or become distorted, the buds below may produce a tight cluster of shortened stems. The resulting dense cluster of twigs growing from a central source looks like it belongs in a witch’s lair, not on the branches of ornamental plants.

 

In many cases it is a disease organism that causes this growth distortion.  It can not be controlled by chemical fungicides.  The best treatment is to keep an eye out for early symptoms, and prune it out according to the steps outlined in today’s column.

Witch’s brooms may be caused by mites, viruses, fungi, mistletoe, insects, or nematodes. Sometimes the effects are a result of natural genetic changes, and may be used to create different looking plants. On trees, witches brooms are easier to see if there are no leaves present.  

But in the case of our evergreen shrubs, infections may go unnoticed until neglect reveals the unsightly growths.

Other Old-world names for this affliction are staghead and hexenbesen. Several different spellings of witch broom or witches' broom have also been used.

Here in Florida, many of the witch’s brooms are a result of a fungal infection from Sphaeropsis tumefaciens.  Many plants in Florida are know to be affected by this disease, including oleander, holly, bottlebrush, citrus, Carissa, crape myrtle, Ligustrum and even the Brazilian Peppertree.  On some of these plants the symptoms produced are a knotty gall rather than the witch’s broom effects.

 

 

Dealing with infected plants

 

Prune branches at least 6 inches below where symptoms are seen.  Look at the cut end of the stem to see if any discoloration from the fungal growth in the wood is noticed.  Prune that branch back further if this is noticed.

 

Prune during dry times, avoiding periods when rainfall is expected 24 hours before or after pruning.  To prevent infection of unaffected plant parts, dip pruning tools in a disinfectant such as 10% Clorox or rubbing alcohol before using them on an  other branch o r plant.

 

For commercial landscapers, I’d suggest that they have a bucket of bleach handy, with several pairs or pruners on hand.  Make one cut, the place the pruner in the bucket, and retrieve another one from the sanitizing solution.   Bleach needs a good 30 seconds to sanitize the pruner surface if this disease is to be killed.

 

Severely infected plants should be removed and destroyed.  No chemical fungicides are available to control witches' broom. We don’t know of any Oleander cultivars that have resistance to this disease.

 

 

 

The newsletter I mentioned above reports on a study now being conducted by UF Horticulturalists.  They are trying to determine if holly cultivars show differences in the susceptibility to witch’s broom.  Early results suggest some differences, but the study needs to continue to see if seasonal differences are part of the infection process.

 

One interesting result of this study is that in some cases it only took four weeks from the time these plants were purposely inoculated until the disease symptoms were observed.  From the standpoint of taking care of your landscape, the lesson here is that infested pruning shears can rapidly spread this disease from on plant to another.

 

So if your plants appear to be left over from last Halloween, be sure to keep your pruners clean and look early and often to stay ahead of this witch’s curse.

 

I’ve placed more information including several photos of this disease on our Okeechobee web page, http://okeechobee.ifas.ufl.edu.  If you need additional information on witch’s broom, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners from 1 to 5 PM on Tuesday afternoons.  

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Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean Last update: 05/18/2006 .  This page is maintained by Dan Culbert  

references

Witch's Broom Nebula by T. A. Rector (U. Alaska)