Corn Rust
Corn rust or Southern rust is a common fungal disease in corn. The disease affects the plant at flowering, fruiting, seedling and vegetative stage.
Puccinia polysora is an obligate parasite. When infected tissues senesce, thick-walled uredospores are produced which survive adverse environmental conditions. Dispersal may be attributed to airborne and waterborne spores from pustules.
What are the symptoms
Symptoms are initially seen as round, light green to yellow spots on the leaf surface that eventually develop into pustules with light cinnamon brown color, circular to oval in shape of 0.2-2mm long and densely scattered on the upper leaf surface. Pustules can also be observed on ear husks, leaf sheaths, ear shanks and stalks.
Impact to the crop
Infection may result in a decrease in photosynthetic activity resulting to yield reduction. For each 10% increase in the severity of rust, yield losses range from 3-8% of potential yield.
How to control
Early detection of disease is important in controlling the disease. Fungicides should be applied in a timely manner usually before the disease spread throughout the canopy and before corn reached near physiological maturity. Fungicides with active ingredients of propiconazole, pyraclostrobin, picoxystrobin, azoxystrobin, trifloxystrobin and prothioconazole or their combination can be applied as a foliar spray.
Source:Dela Cueva, FM, CB Pascual, CM Bajet and TU Dalisay. 2015. Pests and diseases of economically important crops in the Philippines. Pest Management Council of the Philippines, Inc. c/o Crop Protection Cluster, University of the Philippines Los Banos, College, Laguna; Shaner, G. 2000. Corn rust -an epidemic? Botany and Plant Pathology Dept., Purdue Univ. Retrived from https://www.agry.purdue.edu/ext/corn/news/articles.00/Corn_Rust-0713.html
