Impatiens have been the best choice for an annual that will produce fantastic color in shaded areas. Now we may have to go for another option.
Recently, I have noticed impatiens that have suddenly lost all of their leaves and are naked stalks. The cause is downy mildew.
This fungus moved into our area a couple of years ago. It can attack the plants at any stage in the growing season and is aided in its attack by our extreme humidity, particularly at night.
There are a couple of fungicide sprays that will help prevent it and again, prevention is the key to control.
Maneb was a favorite of mine, used to control tomato blights, but it is becoming difficult to find.
A newer organic chemical for control is Excel LG. Its active ingredients are potassium salts and phosphorus acid.
Usually when we have to rely on chemical control to prevent a disease, we recommend two different classifications of chemicals so that the fungus or disease does not build resistance and these two do a great job for prevention.
If you have experienced downy mildew in your impatiens, you will want to be prepared to do battle if you want to continue to use impatiens.
That fungus can remain viable in the soil for years. So, the first step would be to clean up ALL of the infected plant debris and dispose of it in the garbage. If you have containers, do not reuse any of that potting soil for impatiens.
Next spring be sure the plants you purchase are healthy, and not a sickly, off-green color. That color is the first indicator of infection.
I did my first application of Excel LG in mid-June and repeated the spray two more times through the season and I had great success. I’m telling you this now so you can be prepared if impatiens are on your radar for next season.
You can continue to enjoy the color of dahlias, cannas, and glads until our first frost puts an end to that show. These tender bulbs will not be harmed unless they are left in the ground until the soil starts to freeze.
I do clean off the glad bulbs, but I have better results with cannas and dahlias just lifting the whole clump and storing them in what soil comes with the mass of bulbs.
I store them in a cold room in my basement where the temperature doesn’t drop to freezing, but usually stays around 40 degrees.