Dr. Rishi Burlakoti
Weather INnovations Consulting LP, Chatham
Common rust caused by the fungus Puccinia sorghi is an emerging disease of corn in Ontario. The pathogen does not survive in Ontario. The rust spores arrive in Ontario through wind current from the southern United States. The disease is favored by cool night temperature (18 to 22°C), moderate or warm day time temperature and high humidity or wetness hours.
Common rust has been observed this week in Chatham-Kent. The disease is characterized by appearance of brick red pustules in leaves, sheaths, and stalks (Fig. 1). The rust pustules appear in leaves first and later spread to sheaths and stalks. The urediniospores produced in brick red pustules infect the healthy corn foliage and repeat multiple cycles. The disease can quickly spread in the corn fields if high relative humidity and moderate temperature exists.
The weather conditions during the past two weeks in the southwestern Ontario were favorable for common rust infection (Fig. 2). The disease might spread in the region if warm and humid conditions will exist in the next few weeks. However, the disease may not be big concern if hot and dry weather conditions will exist in the region.
Source: weathercentral