Crazy top of corn
Sweet corn Crazy top Sclerophthora macrospora
Scientific Classification
Kingdom: Chromalveolata
Phylum: Heterokontophyta
Class: Oomycetes
Order: Peronosporales
Family: Peronosporaceae
Genus: Sclerophthora
Species: Sclerophthora macrospora

Crazy top
Crazy top of corn

Nozemia macrospora
Phytophthora macrospora
Phytophthora oryzae
Sclerospora kriegeriana
Sclerospora macrospora

Sclerospora oryzae

Crazy top of corn is caused by the soil borne fungus, Sclerophthora macrospora. The disease develops where soils have been saturated for 24 to 48 hours soon after planting. The fungus infects the growing point of the young corn plants usually before the second or third leaf stage, then grows systemically within the plant and develops in the rapidly growing tissues. The systemic growth causes a hormonal imbalance, which initiates the proliferation of leafy tissue in the ears and tassels.[1]


The most characteristic symptom is the proliferation of leafy structures from the ears and/or tassels, In many cases, leafy protrusions occur in only the ears resulting in a mass of strap-like leaves protruding from the ear zone. Affected plants may also have profuse tiller development.[1]


No highly effective control measures can be recommended for crazy top. Very little is known about the level of resistance in corn hybrids to this disease. Proper soil drainage will reduce the risk of flooding and subsequent infection. Avoid planting corn in low wet spots where the disease is known to occur. Seed applied fungicides will not control crazy top.[1]


  1. a b c Thomison, P.; Geyer, A. (2008). Troubleshooting Abnormal Corn Ears and Related Disorders. The Ohio State University. Retrieved: 2010-11-08.

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