Karnal Bunt (KB) was recently found outside the existing quarantine areas in Arizona, California, and Texas. The disease was confirmed in central Texas (San Saba and McCulloch counties) and in new localities in north central Texas (Archer, Throckmorton and Young counties). These areas are now under USDA quarantine. In addition, the USDA is temporarily designating Baylor County, as a regulated area because grain stored in that county may be infected with the fungus. The counties are on the southern fringe of the wheat belt that spans from Texas to Canada. A fair part of the acreage throughout the winter wheat belt is typically harvested by custom harvesting that move north as the crop ripens and ultimately make it into the Dakotas and Minnesota.

Karnal bunt (KB) is caused by a fungal disease (Tilletia indica) that infects kernels of wheat, and triticale. It usually causes minimal yield losses but it can impart a fishy odor to the grain. The disease is not harmful to humans or livestock. It is a quarantined pest for most of the grain importing countries of the world. They will not accept grain unless it can be certified to be from a KB-free production area. Therefore, the severe effect of this disease is on the grain export markets. As part of the quarantine measures the USDA has mandated that all harvesting and cleaning equipments operating in these areas have had to be disinfected prior to moving into another state.

The spread of the disease northward is remote but precautions to keep this problem from reaching Minnesota are still necessary. The USDA has sampled grain at the elevators at random for the presence of KB spores all throughout the USA to establish that certain areas are KB free and meet the export requirements. Presence of even spores that were inadvertently brought up by custom harvesters would pose a great threat. It is recommended for wheat producers in Minnesota to ask custom harvesters and operators of seed cleaning equipment whether they have been in quarantine areas. If so, they are required to have a federal inspection certificate indicating that their equipment has been cleaned and disinfected before they are allowed to enter the fields.

Below is a voluntary cleaning protocol suggested by Vernon Schaffer, director of the Kansas State University Foundation Seed program and Bob Bowden, Extension plant pathologist: Rather than using a vacuum cleaner, steam cleaner, or compressed air, we recommend low-pressure, high-volume water for cleaning. The goal is to remove virtually all of the debris to avoid contaminating the next field. Be aware that this is not as stringent as the protocol used by USDA for cleaning combines from quarantine areas.

Try to do a preliminary cleaning before you leave the old field. Clean off the feeder house and reel, open the trap doors, then run the machine until the loose grain is all out.

1. Select an area for cleaning with access to a water hydrant.

2. Remove the header and clean it separately.

3. Park on pavement where waste grain can be swept up and disposed of properly. You might want to tilt the combine to help drain the horizontal augers.

4. Open all the access doors, traps, and elevators and remove the sieves.

5. Run the machine until the loose grain is all out.

6. Use a garden hose and nozzle to dislodge debris. Start at the front and clean in the direction that grain flows through the machine. That way if you need to run the machine to shake some debris loose, you won’t re-contaminate an area you’ve already cleaned.

7. If possible, remove the concaves and wash the cylinder area. On some machines, the concaves will be very difficult to remove. Try using the water to thoroughly flush them in place. Continue cleaning toward the back of the machine.

8. Clean the grain tank and unloading augers.

9. Run the machine again to shake any remaining grain loose.

10. Don’t forget to look underneath and clean debris and grain that collects on the undercarriage.

11. Dispose of waste grain, weed seeds, and debris in a landfill or bury it deeply.

Cleaning a combine can be hazardous, so always make safety a top priority. Wear proper eye protection and be especially careful when running with the access doors open.