NOTE: The report below is contained in the Jan. 27, 2012, issue of Arkansas Wheat. Download a PDF of the Newsletter.
Wheat stripe rust has been found in Arkansas. On January 20, 2012, Richard Klerk, County Extension Agent in Cross Co. in northeast Arkansas, found stripe rust in a field of an experimental wheat variety that was planted October 6th.
This is approximately two months earlier than stripe rust has been found in Arkansas during previous seasons and appears to be the first report of stripe rust east of the Rocky Mountains in 2012. The affected area is about the size of a small car and plants contain numerous leaves with stripe rust on them.
This stripe rust likely was initiated from a single spore that blew into the field shortly after emergence last fall. The mild winter appears to have been ideal for several cycles of sporulation and re-infection. This early disease development increases the risk of a stripe rust epidemic this season.
What To Do Now??
Scout your fields – At this time; it would be prudent to scout wheat fields to determine the extent of stripe rust infection. It is odd to find stripe rust this far north and have not found any at locations further south. There are likely other fields that do have stripe rust, but have not been located yet.
Fungicide applications are not recommended at this time . If several infection centers of stripe rust are found in fields of varieties known to be susceptible to stripe rust, an earlier-than-normal fungicide application likely would be cost effective. If stripe rust is found in fields of varieties classified as resistant or moderately resistant, it may be more cost effective to monitor disease development to determine if adult-plant resistance is slowing development. Most of the wheat varieties grown in Arkansas have adult-plant resistance to stripe rust. That is, seedlings are susceptible and the plants become resistant as they mature. The level of adult-plant resistance can vary among varieties, and most of the adult-plant resistance appears to be race specific. That is, new races of the pathogen can evolve to overcome this resistance just like races evolve to overcome the more familiar seedling or all-stage resistance used in wheat varieties.
The most recent wheat variety stripe rust ratings can be found at: http://www.aragriculture.org/News/wheat_update/default.htm
Please contact your local county extension agent in Arkansas or the authors by email at, email@example.com, or firstname.lastname@example.org, if you have questions or comments regarding this newsletter.
We sincerely appreciate the Arkansas Wheat Promotion Board and the Arkansas wheat producers for their support. The authors appreciate all feedback and contributions.