Expert: Mike Mascio - 7/9/2007

Question
I have some impatiens in containers.  The leaves look great and there are lots of blooms, but the blooms all develop white streaks and/or clear spots on them.  What is this? I do not see any aphids or bugs.

Answer
Michael, if you have ruled out insects, the most likely causes are excessive water or sun scald.

Impatiens prefer shady conditions. If they are placed in hot sun for prolonged periods of time, the foliage will begin to lose color. Also, if the soil is not draining well, or the plants are over watered, the nutrients in the soil will be depleted, resulting in problems similar to what you have described.

With this in mind, you still should not rule out insects. Many insects, including scale, mites, and minute beetles, are nearly invisible to the human eye. You can spray the plants with an insecticidal soap. This is an organic pesticide which is non-toxic and safe to the environment. You can purchase this product at most garden centers or on line through companies such as Planet Natural or Gardens Alive. Both companies also sell many other organic controls as well.

Finally, if the blooms themselves are the only issue, you may have slugs. Slugs only feed at night when the weather is cooler. They hide under mulch and soil during the day. They are notorious for eating blooms from certain annuals and perennials.

To control slugs, use a granular control such as Sluggo or Escar-Go. Attached is a link to the second product.

http://www.gardensalive.com/product.asp?pn=2111&ss=slugs

I hope this answered your question. Please write again if I can ever be of assistance.

Regards,

Mike