Written by Jeanne Falk Jones, K-State Agronomist for Cheyenne, Sherman and Wallace Counties.

It is that time, when we start discussing rust reports in wheat.  There have been reports of both stripe rust and leaf rust in south central Kansas last week and this week.  For both leaf rust and stripe rust in wheat, we listen to the south for rust reports.  This is because rust spores move north on the wind.  Therefore, I listen for reports in the panhandle of Texas and Oklahoma and southwest Kansas.

First, let’s discuss the reports from Kansas.  Leaf rust and stripe rust were found in low incidence last week in south-central Kansas by a UDSA plant pathologist and wheat breeder as they were checking research plots in Reno County.  Yesterday, leaf rust reports came in for Finney (Garden City), Gray (Cimarron), Ford (Dodge City), Hodgeman (Jetmore), and Edwards (Kinsley) Counties.  So far, it appears to be leaf rust that is most active but stripe rust is also present. The disease is still at low levels and restricted to the low and mid canopy.  Wheat in these areas of the state is jointing but will be at flag leaf emergence soon. Some early fields may already be at flag leaf emergence.  (Report from Erick DeWolf, K-State Wheat Pathologist)

Here is the current map for leaf rust infections in Kansas.  This map was released yesterday afternoon.

The rust diseases were found in varieties of wheat that are known to be susceptible.  This means there is no evidence of changes in the populations of rust fungi to date. The disease was located in mid-canopy and still at low incidences (less than 1%).

I have been out in the field and have not found leaf rust or stripe rust in any wheat I have looked at.  I will continue to scout for these diseases.  If you see something you are concerned about or think you see rust, please let me know.

For Texas, the latest report that I have is from a wheat nursery in Castroville, just west of San Antonio.  The plant pathologist said there was uniform infections of leaf rust on susceptible wheat varieties.  In addition, stripe rust was present on susceptible varieties, but was drying up because of weather conditions.  This report didn’t contain any information on area west of that location, so I haven’t heard a great deal on what they are seeing in western Texas.

For Oklahoma, we received a report last Friday.  This report was from the plant pathologist at Oklahoma State University.  He reported rust beginning to increase in severity in southwest Oklahoma.  This is primarily leaf rust that is being reported and it is quickly approaching a time for the growers in southwest Oklahoma to make a decision about treating with a fungicide.

In addition, the incidence across the rest of the state of Oklahoma has been mixed, with some locations with no rust infections and other locations with very low incidence of leaf and stripe rust infections.  However, given the present and short-term forecast for temperature and moisture, the Oklahoma State University pathologist expect leaf rust to increase.  These conditions also are favorable for stripe rust, but the fact that it is being found in such low incidence, it indicates that the wheat may be more at risk from leaf rust than from stripe rust. (Report from Bob Hunger, OSU Plant Pathologist)

For northwest Kansas, there is no need for you to make management decisions based on these reports right now.  The timing for fungicide applications is when there are flag leaves emerging and rust present on leaves just below the flag leaf.  Mostly, I just want you to know what I am hearing about leaf rust and stripe rust infections to the south and east of our area.

I will keep you up to date on what I am hearing and seeing in the field, in relation to stripe rust and leaf rust.  And if needed, we will discuss fungicide applications and wheat variety resistance.  If you have any questions, please get ahold of me at the K-State Extension Offices in Sharon Springs, Goodland or St. Francis or on the K-State Experiment Station in Colby.  You can see what I am finding in the field by following me on facebook at K-State Sunflower District Agronomy