|In a window box, I planted some New Guinea impatiens with regular impatiens surrounding the edge of the window box. The plants have been thriving for 2 months. Lately, I noticed a white film on the leaves and the plants have been looking sickly. I don't see any bugs. What can be the problem?|
|Based on your description it sounds like the plants are suffering from mildew. This can appear when the heather heats up and the air becomes more humid, especially at night. The best things to try are to thin the plants if they have become crowded and avoid wetting the foliage when you water. You might also consider some of the following steps: If you have a compost pile, make
some compost tea and spray it on leaf surfaces every couple
of weeks, or use baking soda-oil spray (1 tsp. baking soda
and 2.5 tsp. summer oil in 1 gallon of water) sprayed once
per week. A commercial organic alternative is Soap Shield
Fungicidal Soap from Gardens Alive (5100 Schenely Pl.,
Lawrenceburg IN 47025; ph# 812/537-8650).
Be sure to follow the label instructions and test any spray on a few leaves first to be sure your plants tolerate it well. Good luck with your plants!