Many of you have reported a sudden decline in your garden variety of impatiens plantings. This is due to the presence of downy mildew attacking your plants. Spores of this fungal disease are practically present everywhere – on the plants we buy, on our gardening tools (especially pruners), in our soil, and in the air. When we have warm days and cool evenings, these spores become attached to the watery film that develops on plant leaves. Once this moisture evaporates, the fungal spores form a white film on the undersides of leaves, followed by a yellowing and dropping of these leaves. What had been lush mounds of plant growth, turn into tangled messes of gnarled stems and eventual death of the plant.
We’re not alone with this problem either, 31 other states are also encountering it.
So what do you do? If the problem is serious and plants are declining, remove and dispose of the infected plants. Don’t replant impatiens in that same area, or if previously planted in containers, don’t reuse the soil. The best control in to provide good culture, sanitation, and close monitoring of your plants. If found in the early stages of development, you can apply either OrthoMax Fungicide, Neem Oil, or liquid copper fungicide, according to the package label.
To sterilize tools or pots that may have been contaminated with this disease, dip them in a 5% bleach solution, which will kill the spores.
New Guinea impatiens are reportedly not affected by Downy Mildew.