By Dr. Nathan Kleczewski, Research Assistant Professor and Extension Pathologist
It seems hard to believe, but soon we will be planting our winter wheat for the 2020 growing season. Diseases were not a major issue in Illinois this season and only some pockets of fields in parts of the state suffered from Fusarium head blight (FHB) at levels that resulted in vomitoxin (DON) contamination and reduced yields.
Successful management of FHB must include an integrated approach. No single management strategy will be effective at reducing yield loss and vomitoxin contamination in a disease-favorable environment. We cannot completely stop damage from FHB, but we can suppress its effects and reduce yield damage. The first and most important tool growers have in their tool box is the use of a variety with moderate resistance to FHB. Varieties with moderate resistance to FHB will have reduced yield losses compared to susceptible varieties and will help reduce vomitoxin contamination in the grain. As we are all aware, if the vomitoxin content in the grain exceeds the maximum acceptable levels, the grain will be docked or deemed not be acceptable for sale. My goal as an extension plant pathologist is to help producers effectively manage FHB so that the vomitoxin levels in their grain is below the acceptable thresholds allowing for the sale of their grain.
Vomitoxin advisory levels for wheat in the United States
| Animal | Maximum Acceptable DON Level |
|---|---|
| Swine | 5 ppm: Not to exceed 20 percent of ration with finished feed |
| Beef and feedlot cattle more than 4 months old | 10 ppm: Not to exceed 50 percent of diet with finished feed |
| Poultry | 10 ppm: Not to exceed 50 percent of diet with finished feed |
| Other animals | 5 ppm: Not to exceed 40% of diet |
| Human consumption = 1ppm |
In research conducted from 2007-2010, the use of moderately resistant varieties reduced severity of visual symptoms of FHB on wheat heads and grain by over 50% compared to susceptible checks (yellow bars in Figure 1a and 1b). Additionally, when using an FHB fungicide such as Prosaro or Caramba, the use of a MR variety reduced FHB and DON by over 70%.
Let’s put that in perspective. Grower A plants a susceptible variety and doesn’t spray for FHB, and grower B plants a MR variety and sprays with Caramba or Prosaro at FGS 10.5.1. Both varieties are stripped 3x into the same field. If average DON for grower A comes back at 10 ppm, then we would expect the average DON for grower B to come in around 3 ppm. Grower A will likely need to dispose of his/her grain, but grower B can sell his as feed quality grain.