Growers across the country are scrambling for solutions, with the discovery of downy mildew on impatiens in the U.S. landscape. Look for these symptoms in the greenhouse when you’re scouting your impatiens crop this year:
• Plant foliage that’s yellowish or pale green in color
• Leaves that curl downward
• Leaves that are distorted
• Undersides of leaves that have white or light gray fuzz present
• New and emerging leaves that are small and a discolored yellow or pale green
• Flower buds that fail to form
• Stunted plant growth
If you see one or more of these symptoms on a plant, immediately seal it in a plastic bag before removing it from the greenhouse. Get it to a diagnostic lab for further testing.
Additionally, when spraying for downy mildew, there are three important things to remember when applying fungicides:
1. Apply fungicides preventatively.
2. Rotate among products with different modes of action to prevent resistance.
3. Be timely in re-applications.