Can someone explain what the white spots are on my impatiens leaves-they seem healthy otherwise.?

Question

These spots appear on my impatiens around August each year and I would like to know what causes them and if they are harmful to my plants. Are they preventable?

Answer 1

could be sunburn

if there is water on the leaves during the day and the sun is shining and it is hot you will be sunburned leaves

this might help:

http://yardener.com/YardenersPlantHelper...

Answer 2

Powdery Mildew

http://www.agriculture.purdue.edu/produc...

It doesn't take as much for Powdery mildew to grow as other funguses.   Try spraying the leaves with water first as this usually can get rid of it.  If it doesn't go away use a fungicide.  

Answer 3

Could be spider mites that will kill their host plant in time.  Look under the leaves for very fine webs and the mites (about the size of this period  .  )  Imps are prone to mites.  Disyston (systemic pesticide) will murder them.  You can use a pistol grip sprayer, fine spray setting, blast them off with water (they'll be back).  There are also pesticidal soaps/oils available.

Imps root in water, take cuttings for more plants.  (They'll overwinter indoors.)