Southern rust of corn can be an extremely damaging disease of corn if weather is favorable and if infections occur early enough in the season for yield losses to occur. Although southern rust does not impact corn yields in Kentucky every year, the 2016 growing season was an example of a year where southern rust reduced yields by up to 60 bushels per acre in some fields. Fortunately for Kentucky corn growers, southern rust does not overwinter much in the U.S., but it does survive in southern North America (such as Mexico) and Central America where corn may be grown year-round. Infections in the U.S. during the growing season are dependent upon the southern rust pathogen traveling northward in weather systems and on local weather to be favorable for infection and disease development. In states like Kentucky, we generally can watch the movement of southern rust into states to the south and make predictions on when it may move into Kentucky.

Dr. Carl Bradley began coordinating monitoring of southern rust of corn in the U.S. for the 2017 growing season. To do this, maps were created on the iPiPE online system (https://ext.ipipe.org/). Dr. Bradley received observations of southern rust of corn and added them to the iPiPE map. These observations came from extension plant pathologists from across the U.S. In addition, observations posted on the social media platform, Twitter, were used as additional observations. Dr. Bradley created a Twitter handle, @corndisease, and coordinated a Twitter campaign for users to tweet @corndisease pictures of corn diseases, including southern rust, along with the county and state they were observed. The @corndisease Twitter account is the primary way that stakeholders were informed of new southern rust observation maps being posted on the iPiPE.

During the 2017 growing season, July 1 to September 30, 2017, tweets from @corndisease earned over 79,600 impressions. Over 1,500 Twitter users follow @corndisease, and rely on this Twitter account and the iPiPE to know the whereabouts of southern rust in the U.S. Although southern rust was observed in Kentucky in the 2017 growing season, movement into Kentucky and spread of the disease was slowed due to hot and dry weather. Crop consultants, corn growers, and others in the ag industry that followed the @corndisease Twitter account and iPiPE southern rust observation maps, used this information to make decisions on spraying a foliar fungicide for management of southern rust. 

This project was funded by a grant from the United States Department of Agriculture National Institute of Food and Agriculture through the Integrated Pest Information Platform for Extension and Education (iPiPE) Cooperative Agricultural Project (CAP). In addition to the outputs mentioned above, a multi-state extension guide on southern rust of corn was developed (Bradley et al., 2017) and is available on-line at: https://cropprotectionnetwork.org/, and a peer-reviewed journal article is currently in-press that reports on using the social media platform of Twitter to track plant diseases (Mueller et al. 2018).

References:

Bradley, C., Allen, T., Faske, T., Isakeit, T., Jackson-Ziems, T., Mehl, K., Mueller, D., Sisson, A., Tenuta, A., Weems, J., and Wise, K. 2017. Southern Rust. Publication no. CPN-2009-W, available on-line at: https://cropprotectionnetwork.org/.

Mueller, D. S., Sisson, A. J., Kempker, R., Isard, S., Raymond, C., Gennett, A. J., Sheffer, W., and Bradley, C. A. 2018. Scout, snap and share: First impressions of plant disease monitoring using social media. Plant Disease (in press). (Will be available on-line at: https://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS-11-17-1862-SR).