Cercospora leaf spot disease is a fungal infection that is largely cosmetic in most cases. However, if the disease is left unchecked over time, it can cause defoliation and weaken the plant, allowing infection from other diseases. Being aware of the signs and symptoms of cercospora leaf spot, as well as the appropriate response to it, will help you keep your plants happy and healthy.
Cercospora infects plants by splashing onto lower leaves during hard rains. As the infection starts to create spots and even holes in the leaves and new spores form, the cercospora spreads throughout the upper levels of the plant, invading the entire canopy of trees in some cases. Left unchecked, the disease can cause the canopy to yellow and wither, ultimately leaving the plant open to other infections.
Cercospora leaf spot starts out with spots appearing on the leaves of the plant. These spots may be brown, purple or gray. They may be ringed with a light tan color. Leaves that are heavily spotted often turn yellow and eventually fall off the tree. When cercospora infects a plant, it often creates the necessity for the plant to produce more leaves over the course of a growing season to replace the ones that have been lost. This can stunt the growth and yield of the plant.
Cercospora is best prevented by removing plant debris from underneath plants before the growing season begins. Rake away all debris and dispose of it by burning or in a sealed plastic bag. If you fertilize, do so with a slow-release nitrogen and potassium fertilizer.
If your plant has already been infected with cercospora, then you will need to use sterile pruning techniques to remove all impacted foliage. Wipe your clippers down with rubbing alcohol after each clip, and dispose of all pruned vegetation by burning or in a sealed plastic bag. You can also fertilize your tree with a quick-release treatment of nitrogen fertilizer. Mancozeb, a chemical pesticide, will eradicate the problem in most cases, but it must be applied by a licensed professional.
Ideal Cercospora Conditions
Cercospora is largely a problem in warm areas that are wet and humid. When the spring season involves heavy, frequent rains, this fungus is most likely to infect plants and trees. Generally, areas with temperatures between 68 and 95 degrees Fahrenheit are good for disease development and infection.