Anyone who has planted Periwinkle, or Annual Vinca, in the spring in Central Texas will tell you “that plant always dies when I plant it”. Well, there is a reason for that! Periwinkle, especially in the “old” days, before resistant varieties were available, was never grown until the cool wet weather ofspringwas behindus. It absolutely thrives in the scorching hot summers, but give itrain and cool weather, and disease takes over! Phytopthora fungus is the causal organism for both Aerial blight and Root blight on Madagascar Periwinkles. As mentioned above, the disease thrives in cool wet weather. Most bedding plant growers will not even attempt to begin growing it until the weather has begun to warm, for that reason. This aggressive disease is soil borne, and causes the plant to wilt,turn black and die. Once the Phythopthora fungus is in the soil, it is very difficult to control if the conditions for the disease are there.In the “old” days, we would “fumigate” the soil with chemicals that are no longer used. Thankfully, we now have biological means to control this destructive fungus.The “secret” to planting Periwinkle in the spring is to choose resistant varieties (almost all plants on the market today are resistant), and to spray the plants and inoculate the soil with a bacterium called Streptomyces lydicus. Thisissold as a wettable powder called Actinovate. When introduced into the rootzone or applied to the foliage, S. lydicus colonizes plant structures and forms a mutually beneficial relationship by feeding off of the plant’s waste and secreting beneficial byproducts. These byproducts have a high level of chitinase (an enzyme) that breaks down chitin, a key structural component of fungal cell walls. This forms a defensive barrier around the plant, which in turn keeps pathogens out.Our favorite organic multi-purpose fertilizer, MicroLife 6-2-4 also contains strains of Streptomyces lydicus. Using either of these organic products will help control Phytopthora fungus on early-planted Periwinkle.Don’t forget to plant them in well-drained soil and let the soil approach dryness between watering.