- A small number of fields were treated with a fungicide for leaf rust during the 2012 season.
- Inoculum to initiate a rust infection (either leaf, stem, or stripe rust) must blow in from somewhere south of Mississippi where the inoculum overwinters on alternate hosts.
Based on the 2012 season, and the overall amount of leaf and stripe rust that were observed in Mississippi, we were able to rate six wheat variety trial locations for the presence of rusts.
Typically, leaf rust is encountered on an annual basis but doesn’t amount to much of an issue.
A small number of fields were treated with a fungicide for leaf rust during the 2012 season. However, I suspect that the environment at those locations was more conducive for the development of the disease and this will not likely be an annual occurrence.
Keep in mind that the inoculum to initiate a rust infection (either leaf, stem, or stripe rust) must blow in from somewhere south of Mississippi where the inoculum overwinters on alternate hosts.
Just because you had rust in a wheat field during 2012 does not mean that it will be back in 2012-13 if you choose to plant a particular field to wheat.
In addition, stripe rust, the more aggressive wheat rust, was observed on more acres during 2012 than in the recent past.
Stripe rust can be an annual disease but more often than not the disease doesn’t threaten yield.
The environment during the 2012 season throughout much of the state was conducive for the development of stripe rust.
However, additional factors such as race of the fungus or susceptibility of the particular variety planted at a particular location can also result in increased disease incidence.
Regarding the ratings conducted, keep in mind that the six locations were geographically distinct within Mississippi (Brooksville, Fitler, Minter City, Newton, Renova, Stoneville) and the reaction of a wheat variety at that particular location to disease or other variables (e.g. yield) may have differed.
The entire wheat variety trial booklet can be accessed at: http://msucares.com/pubs/infobulletins/ib0469.pdf.
Also, the races of leaf and/or stripe rust may differ by location. so looking at the data across locations will allow you to make a more informed decision as to the overall tolerance of a particular variety to stripe rust (or leaf rust).
I have included the disease reaction information regarding the reaction of each of the 73 different varieties contained in the Mississippi wheat variety trials from 2012 (2012 wheat disease reactions).
Values in the table include the percentage of the flag leaf infected by either leaf or stripe rust.
Note that stem rust did occur, but was only observed at incredibly low levels on two varieties at a single location (stem rust infection was noted on the stem of the plants contained within the plots that were infected).