Greenhouse and Landscape - Pansy Diseases

Keep your eyes out for two diseases of pansy that have been increasing over the years.

Black root rot shows up just about anytime in the greenhouse and landscape. If plants are not establishing or declining without any obvious leaf spotting or other problems carefully dig the plants and check out the roots. If roots are black to very dark suspect black root rot and send in a sample.

Control: in the greenhouse keep medium pH between 5.5 and 6.0 do not reuse plug flats without sterilizing; control fungus gnats. Chemicals that work best as preventative treatment include thiophanate methyl (3336, Fungo) Medallion and Terraguard.

Cercospora leaf spot. Look for irregular spots with dark red- brown margins. This disease can be found in all stages of crop production as well as in the landscape. In the greenhouse try and keep the foliage dry, check frequently, rogue out badly spotted plants from the greenhouse. Fungicides for outside and inside use to control Cercospora leaf spot include Daconil, Compass, Heritage, Insignia, or SI’s such as Eagle (or Immunox for home use).

Information from Bob Mulrooney, Extension Plant Pathologist, UD