Causal Agent: 

Fungus (Puccinia sorghi)

Characteristic Symptoms:
 
Pustules of common rust are large, circular to elongated with brown or cinnamon brown color.
   
Conditions for Disease Development:
 
Rust is favored by moist, cool temperatures and high humidity.
   
Hot, dry conditions typically slow or stop disease developement.
   
It is spread by the wind although leaf wetness is required for infection. Cool, moist conditions favour the disease. 
   

The fungus can survive on brassica weeds, in crop debris or soil for several months, even in the absence of a host.

   
Management and Control:
 
Plant resistant varieties (if available).
   
Plow in old crops as soon as harvesting is completed and ensure all crop residue is decomposed before planting.
   
The disease is spread by windblown spores.
   
Apply fungicides such as difenoconazole (e.g. ScoreⓇ, MontanaⓇ, PursueⓇ, BashⓇ), azoxystrobin (e.g. Amistar®, MiradorⓇ, RobatoⓇ), pyraclostrobin (e.g.Cabrio 25 ECⓇ), chlorothalonil (e.g. Daconil®, Agronil®, Yoda®, Rover®, Yoda 500Ⓡ, tebuconazole (e.g. Folicur 25 WPⓇ, OriousⓇ).
   
 
   

References

https://www.pioneer.com/home/site/ca/agronomy/crop-management/corn-insect-disease/common-rust-of-corn/

The CIMMYT Maize Program. 2003. Maize Diseases: A Guide for Field Identification. 4th edition. Mexico, D.F.: International Maize and Wheat Improvement Center (CIMMYT).

To view other diseases,  click here.

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