Cercospora Leaf Spot

Cercospora species

The various species of this fungus attack carrot, corn, eggplant, pepper, soybean, tomato and more. This disease is sometimes confused with Anthracnose, but produces round or angular brown spots with green, brown, gray or white centers. The leaves eventually die and the whole plant can become defoliated. It is most often a problem in cool (55 to 65 degrees F) wet weather. Actually it doesn’t really matter if you get this disease confused with Anthracnose because the treatments are pretty much the same in both cases.

Prevention

The spores overwinter on volunteer plants and weeds and can be spread to your crop plants by wind, rain or you (don’t work when plants are wet). Reduce these sources of infection by eliminating infected plants, volunteers and weeds. Give plants plenty of water and nutrients, good air circulation and well-drained soil. Rotate crops for 4 years.

It can also be seed borne too, in which case you can kill spores on seeds by treating them with hot water (127 degrees F for 25 minutes) or a bleach solution (1 part bleach to 10 parts water for 30 minutes).

Images: Howard F. Schwartz, Colorado State University, Bugwood.org