Article recevied from Dale Cown, Senior Agronomist SCS / Sales Manager AGRIS – July 5, 2013
By now you have all seen or heard of the increased incidence ( number of heads infected) and severity (amount of head impacted) in both fields treated at T3 with Prosaro or Caramba and fields not treated. It would give the farmers that used T3 fungicides a reason to think it did not work. Why do treated fields have FHB?
- T3 fungicides are intended to offer suppression of FHB not total control, usually 60% control is typical- good to review that fact it is often forgotten.
- In a year like this one with ample rainfall and humidity we have had and continue to have perfect conditions for FHB
- We are seeing whole heads consumed and the top inch or two of the stems, like other living things it needs a food source so it keeps growing where it can find nutrients
- FHB is endemic ( always present) in our soils , it just needs a host (wheat) and conditions ( wet weather and moderate temperatures ) to infect. Not if, but when.
- We have had those perfect conditions
- The 60% control or suppression is challenged in a year of overwhelming disease environment and ongoing conditions for FHB to keep growing on the heads
- It still may well mean that DON production is reduced relative to untreated fields
- We likely will still see a yield boost from the fungicides, our typical 6 to 8+ bushels
- Encourage harvest to start early and pay drying charges
- FHB and DON stop growing when grain moisture drops to 18%
- When harvest is delayed by rain or heavy fog and the grain moisture rises above 18%, FHB and DON production start up again
- Each rain delay adds moisture and resumption of FHB growth and adds to the pre-existing DON level from before, it is accumulative
- Most farmers are aware of combine settings however setting higher fan speeds will blow the light infected kernels out the back of the combine and make for a better sample, DON will be highest in the light chaffy grain and fines.
- On a long shot bet we may get surprised and have lots of FHB but low DON levels. Testing will be the only way to know that
- What we do know for certain is the development of DON is a field disease issue.
- The longer the crop is in the field the greater the risk for higher infection levels
- Harvest as early and as fast as possible