Botryosphaeria Dieback of Eugenia, Ligustrum, Oleander

Stephen H. Brown, Horticulture Agent
Lee County Extension, Fort Myers, Florida
(239) 533-7513 [email protected]
Brown’s Webpage
Aaron Palmateer, Plant Pathologist
Tropical REC, Homestead, Florida [email protected]
Botryosphaeria Dieback of Eugenia, Ligustrum, Oleander,
Pittosporum, Viburnum ’Awabuki’ and Wax Myrtle
Introduction
Eugenia (Syzgium paniculatum), Ligustrum (Ligustrum japonicum) , Oleander (Nerium oleander), Pittosporum (Pittosporum tobira), Viburnum (Viburnum odoratissimum ’Awabuki’) and wax myrtle
(Morella cerifera) are six ornamental plants common to South Florida landscapes. Dieback of these
plants are sometimes attributed to the fungus Botryosphaeria. Disease symptoms includes yellow, spotted and blighted leaves, dried leaves, defoliations, cankers, tip diebacks, branch diebacks, and often
death of the entire plant. Plants in a hedge row are often randomly affected with no discernable pattern.
Disease symptoms may be present at any time of the year.
Botryosphaeria
Genus Botryosphaeria contains fungal plant pathogens that are capable of causing disease that affects a
broad host rang of plants. Botryosphaeria is the sexual stage for many species of fungi. Botryosphaeria
are often identified by their morphological characteristics. (i.e. the size and shape of their spores). Spore
production allows for accurate laboratory identification of Botryosphaeria species.
One example, Neofusicoccum parvum was specifically identified as causing dieback of Eugenia. Neofusicoccum parvum is the asexual stage of the fungus that belongs to the Botryosphaeriaceae. The pathogen has been associated with dieback on many other tropical and subtropical hosts, including avocado,
citrus, eucalyptus, and mango.
Management Recommendations
The management recommendations are the same for the related Botryosphaeria pathogens and the diseases they cause in ornamental plants. Good sanitation measures are recommended to manage this disease. It is best to sanitize pruning shears between each plant that has been pruned. There are numerous
disinfectants commercially available at home or hardware stores for this purpose. One can also make
their own disinfectant solution.
Once symptoms (i.e. branch dieback) are present, the affected tissue should be pruned a minimum of 4
inches below the lowest symptomatic branch on the main stem. After pruning, ensure that the exposed
vascular tissue of the freshly cut stem is not discolored. If discoloration remains, cut lower on the stem
until only healthy tissue remain.
Chemical control options are available and should be applied as a preventative. The complex of fungi
belonging to the Botryosphaeriaceae usually cause disease when the host plant is under stress such as
drought or a nutritional disorder and disease is generally most severe under hot and humid conditions.
Consequently, preventative management should begin with fungicide applications in early to mid-spring.
Triazoles are products such as Myclobutanil, propiconazole, tebuconazole, or triadimefon. These products provide systemic activity with the ability to get into the plant tissue. Another group of systemic fungicides is the strobilurins, which include azoxystrobin, pyraclostrobin, and trifloxystrobin. Many contact
fungicides, which do not have the ability to get into the plant’s vascular tissue, provide cheaper alternatives but are generally applied more often and at higher rates that systemic fungicides. Active ingredients for contact fungicides include captain, Chlorothalonil, copper formulations, and Mancozeb. When
using contact fungicides adequate coverage is very important and the product should be applied to
freshly cut plant tissue.
Eugenia —Early October
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Yellowing and spotted leaves
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Twig dieback
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Plant dieback
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Stems with cnacker
Eugenia—Early October
Moderately affected
Most affected
Least affected
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Various degrees of Botryosphaeria affected plants that were used to conceal an conditioner
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Sporadic dieback of plants in a hedge row
Ligustrum—Late June
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Botryosphaeria sections of this shrub have been removed
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Affected leaves
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Discolored affected stems
Oleander —Early November
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Two dead oleander trees are among others of the same species
Dried leaves and stems
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First signs of cankers that may eventually girdle
the tree
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Limb dieback
Pittosporum—Mid July
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Affected hedge midsection
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Affected leaves
‘Awabuki’ Viburnum — Late May
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Botryosphaeria affected hedge row with “recovering” and defoliated plants
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Large canker
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Defoliated plants and exposed cankers
Wax Myrtle — Late August
The removal of infested stems leaves large holes in the canopies of two wax myrtle plants
Degrees of stem infections
Stem canker
The Necessity of Laboratory Analyses
Disease symptoms of various fungi are often similar in appearance. A laboratory analysis is often necessary to determine the cause of a plant’s decline and consequently recommended treatment. You may
submit plants for analysis to UF Extension Plant Diagnostic Center, 2570 Hull Road, Gainesville, FL
32511. Phone (352) 392-1795, Fax (352) 392-3438.
References
Harmon, P.F. and Bledsoe, S.D. 2012. Professional Management Guide for Ornamental Plants. #PP202.
UF/IFAS, Gainesville, Florida
Palmateer, A.J. and Tamowski, T.B., 2011. Branch dieback of Syzgium paniculatum (Eugenia). EDIS
#PP283. UF/IFAS, Gainesville, Florida
Useful Links
Anthracnose
Indian Hawthorn Diseases and Disorder
Fungicide Survey of Lee County
Hibiscus Insect Problems
Key Plants / Key Pests
Stinkhorns
Whitefly (Rugose Spiraling)
Florida Native Palms
Florida Native Plants Fact Sheets
This fact sheet was reviewed by Peggy Cruz, Lee County Extension
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, religion, age, disability,
sex, sexual orientation, martial status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension
Service, University of Florida, IFAS, Florida A. & M. 1/2013.