7/2/2013 - By Marshall Horsman

Later in the month of May with the late spring /early summer rains, Cercospora hydrangea will start to ap­pear in the nursery on Hydrangeas. Many nurseries produce this plant which is why we are focusing on it this month, now is the time to start your preventative sprays to control this leafspot. Also known as “Frog Eye” spot, this fungus usually has a tan to brown center surrounded by a reddish to purple halo. This disease usually starts on the lower portion of the plant, spores overwinter on leaf debris and the soil and splash up to new leaves in the spring during watering and rain events. Cercospora rarely will kill a host plant, but is rather aesthetically unpleasing and can defoliate a plant in severe infestations. The preventative approach should be used to control this disease, spray Heritage, Daconil, Dithane, and Eagle starting now, every 14-21 days through the summer.

By Matt Shultz, Horticultural Tech Support Specialist and Sales Representative, Harrell’s LLC and Marshall Horsman, Technical Services Manager, Harrell’s LLC.