Southern Bacterial Wilt on Marigolds
Ornamental Disease Information Note 9
R.K. Jones, Plant Pathologist (retired)
D.M. Benson, Plant Pathologist

Distribution and Host Range

Southern bacterial wilt, caused by Pseudomonas solanacearum, is a widespread and destructive disease of numerous crops in the warm climates of the world. It is a major disease of tobacco, tomato, potato, dahlia, geranium, hollyhock, hydrangea, marigold, nasturtium, zinnia and others. Bacterial wilt is the most frequent disease problem of marigolds in North Carolina landscapes.

Symptoms

Infected plants may become stunted with foliage light green to chlorotic (yellow) or grey green in color. The upper foliage may wilt slightly in the early stages of the disease but the plant rapidly wilts completely. Diseased plants often die within 7-14 days after the first symptoms are observed.
Control

Southern bacterial wilt is a difficult disease to control. There are no chemicals that provide effective control before or after planting.

The only control is to avoid susceptible plants or to grow resistant cultivars. The following marigold cultivars are resistant to bacterial wilt: Cupid; Irish Lace; Papaya Crush; Pineapple Crush; Pumpkin Crush; Rusty Red; Sparky; Sparky Mix; Bonanza Yellow; Choice Mix; Copper Canyou; Cupid Mix; Fort Knox; Golden Harmony; Goldie; Gypsy Dancer; Naughty Marietta; Orange Lady; Senator Dirksen; and Tangerine Gem. If it is necessary to grow a susceptible cultivar in an area where the disease has been a problem in the past, plant the susceptible cultivar in another part of the area or plant them in new soil or a soil-less media in planter boxes.

Other Resources

For assistance with a specific problem, contact your local North Carolina Cooperative Extension Service personnel.

Last update to information: March 1996
Last checked by author: May 1996
Web page last updated on Dec. 2000 by A.V. Lemay