Sclerotinia species are soil-borne and persistent pathogens which enter greenhouse production as sclerotia on cuttings or infected native soil contamination. The pathogens produce hard survival structures termed sclerotia which resemble peppercorns or mouse droppings. These germinate and infect plants at the soil line where they cause stem cankers and crown rot. The most common causal species is Sclerotinia sclerotiorum which is favored by moisture and high humidity. Avoid overhead irrigation and/or irrigate early in the day to allow quick drying. Protective applications of fungicides require thorough plant coverage (add a spreader/sticker). Appropriate fungicides (26 GT, 26/36, Cleary's 3336, Compass, Contrast, Sextant, Medallion, and/or Terraguard) may also be incorporated into soil to inhibit germination of sclerotia. Check labels for host appropriateness.
