Bacterial blight of Lobelia

Bacterial leaf blight of Lobelia, caused by the bacterium Pseudomonas viridiflava, was recorded on nursery plants for the first time in Victoria in 2008. P. viridflava has been described as a multi-host bacterium.

Limited information is available on how this disease is distributed across nurseries in Victoria. In one detection in Victoria, 100% of the crop was decimated by the disease.

Symptoms of bacterial blight of Lobelia

The disease starts as leaf spots but develops into a blight. The following symptoms can indicate bacterial blight of Lobelia:

  • Initial leaf spotting on the flowers and leaves of Lobelia plantlets — these leaf spots are surrounded by a distinct brown border.
  • Leaf spots can appear on margins of older leaves.
  • Initially, leaf spots are water-soaked. Later they become brown, dry and papery, giving a blighted appearance.
  • Affected plants eventually die.

Managing bacterial leaf spot

Key management practices include:

  • employ good sanitation
  • avoid handling plants when they are wet
  • avoid overhead head irrigation during the evening and night
  • rogue out infected plants.

Exotic Plant Pest Hotline

To report suspect exotic or unusual pests and diseases, call the Exotic Plant Pest Hotline on 1800 084 881.

Page last updated: 19 Aug 2021