Southern wilt of Mandevilla

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Mandevilla, a flowering vine, is occasionally grown in Michigan for use in containers and hanging baskets. This plant can be troubled by several insect pests and a few fungal leaf spots. Growers should also be aware that it is susceptible to Ralstonia solancearum, the bacterial pathogen that causes southern wilt.

Ralstonia solancearum is divided into several different races and biovars. A biovar 3 strain of R. solancearum can infect and cause disease of Mandevilla. Please note that the biovar 3 strain, which causes disease on Mandevilla, is distinct from the strain classified as a select agent (race 3, biovar 2). The strict regulatory guidelines associated with the presence of race 3 biovar 2 do not apply to biovar 3.

Symptoms of R. solanacearum infection on Mandevilla include yellowing and browning of the lower leaves, leaf drop, wilting, and plant death. R. solancearum does not seem to cause distinct leaf spots on Mandevilla, this helps distinguish the symptoms from those caused by the fungal foliar pathogens that affect Mandevilla.

Symptomatic plants should be tested for R. solanacearum. Testing can be done at a diagnostic lab or in the greenhouse with ImmunoStrip tests available from Agdia, Inc. Identification of the specific biovar requires more involved laboratory testing, please contact the MSU Diagnostic Services lab for more information on biovar testing

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