Submitted to: Journal of the Mississippi Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 20, 2003
Publication Date: April 20, 2003
Citation: ABBAS,H.K., BRUNS,H.A., FIRST REPORT OF CRAZY TOP IN MISSISSIPPI DELTA CORN (ZEA MAYS), JOURNAL OF THE MISSISSIPPI ACADEMY OF SCIENCES, 2003. v. 48 (2). p. 117-118. Interpretive Summary: Crazy top is a disease of corn that causes ears and tassels to change into leaflike structures. This is caused by the fungus Sclerophthora macrospora. This disease has not been previously reported in Mississippi. The widespread occurrence of the disease in one growing season suggests that the pathogen may be common and the disease may reoccur given an appropriate environment. The present study suggests that this disease can be avoided with attention to good drainage practices.
Technical Abstract: Crazy top is caused by the fungus Sclerophthora macrospora, which also causes downy mildew. It is a distinctive disease of corn (Zea mays) and can cause economic losses in localized areas. During surveys carried out in 2000 in 15 corn fields located in three counties of the Mississippi Delta, the relative number of plants infected with crazy top ranged from 5 to 40%. In 2001, less than 2% of plants were affected. In 2002, no disease has been observed yet. Diseased plants showed varying symptoms. Infected plants were sometimes taller, and tassels proliferated into a mass of leaf-like structures. Infected ears became a mass of leafy structures instead of a normal kernel filled cob surrounded by a husk. Where kernels normally developed, chlorotic, leafy striping grew. Some infected plants did not have any ear involvement. The fungal structures (S. macrospora) were detected in infected plant tissues by staining with zinc chloriodide. The mycelium stains a deep purplish-blue, while the host tissue remains nearly colorless. The fungus was not isolated using PDA. In conclusion, crazy top was identified on corn in the Mississipi Delta. The disease incidence was more prevalent in 2000 because of heavy rainfall immediately after crop was planted. This disease is seldom of economic importance but can be avoided if fields are properly drained. The widespread occurrence of the disease in one growing season suggests that the pathogen may be common and the disease may reoccur with appropriate environmental conditions.