My Asiatic Trilliums have what looks like a Botrytis infection for the fourth year in a row, and when I checked them today the infection appears to have spread to a nearby T. rugellii. Can anyone recommend a systemic fungicide that can be used on Trilliums? Triforine maybe?
From Case and Case, Trilliums (Timber Press 1997) (emphasis added): The disease appears on leaves or flowers in early summer, usually after a period of very humid or rainy weather. At this time tree leaves shade the plants from any beneficial fungicidal action of ultraviolet rays. Plants that have been stressed are most susceptible. In trilliums, the leaves suffer. ... The process weakens rather than kills, but if the plants become infected for several years in a row, they may cease to flower or even die. If detected early and the plants sprayed with a fungicide, Botrytis can be stopped in its tracks. Repeated spraying may be necessary as indicated on the fungicide's instructions. Systemic fungicides, if not toxic to trilliums, offer the best protection, for they become absorbed into the plant's tissues throughout, preventing the invasion of the fungal hyphae at any point. Do not spray all your plants with any one fungicide until you have tried it experimentally on a few for signs of phytotoxicity. Note: There is a consumer relations phone number on all fungicides, so that you can contact the company and ask specifically about toxicity to trilliums. You could also contact Wallace Hansen, who recommends spraying with Captan or Aliette. http://www.nwplants.com/plants/perennials/trillium/index.html.
Thank you both for suggestions and links, it's probably too late to spray them this year, but I'll make sure to have a bottle ready for next spring. I'll try to replant one of the T. camschatcense as well, maybe that will make a difference.
