Watch for rust on hollyhock. This is the most common disease on hollyhock
and can cause serious injury as leaves are progressively killed through the
summer. Look for yellow spots on the surface of the leaves and orangish to
brown pustules on the underside. Infections can also take place on stems and
green flower parts.
The first line of defense is to remove all hollyhock stalks, leaves and
other debris in the fall and destroy them. Remove any infected foliage you
see now. Just be sure the foliage is dry so you don’t spread the disease.
Continue to remove diseased leaves as soon as they show spots.
Try using a fungicide such as sulfur or myclobutanil (Immunox or Immunox
Plus) to protect healthy foliage. Note that sulfur may burn leaves if the
air temperature is over 85 degrees within 24 hours of application.
Follow label directions for timing and rate.
By: Ward Upham