By Ryan McAllister, CCA, Beck’s Hybrids Team Sales Agronomist
Towards the end of last week and so far this week, I have been in numerous wheat fields all over the state of Ohio, from as far south as Chillicothee to as far north as Defiance. I have visited several fields in east central IN as well and am finding very high percentages of head scab in wheat. Here are some facts for you. Fusarium head blight of wheat, also called head scab, is caused mainly by the fungus Gibberella zeae. This happens to be the same fungus that caused growers in IN/OH vomitoxin problems in their corn last year. Therefore, the potential exists for vomitoxins to be of concern in this wheat crop as well. From flowering to early dough, temperatures of 75-85 degrees are required for infection with light to moderate rainfall for as little as 2-3 days during this time. It is safe to say that conditions were just right for head scab to appear. Unfortunately, many fungicides that are most commonly used do an average job at best of controlling head scab. There are several new fungicides on the market with a “Good” rating for head scab. However, any attempt to spray now would simply not work. Infected heads will appear light in color, almost a bleached look and sometimes will have pink on the head from the gibberella fungus.
At harvest, the combine may be adjusted so that light-weight kernels are removed along with the chaff. However, this will not remove all head scab kernels because some scab infections occur late in the development of the kernel, and these infected kernels still may be fairly plump. The majority of the heads I have seen however have little to no grain in the infected heads. Fortunately or unfortunately, however you want to look at it, it is fairly simple to get an idea of potential yield losses. I use the assumption that if 50% of the heads are infected, you can just about bet on close to a 50% yield loss. Most of what I have seen is in the range of 25-50% infections.
What to do? Caramba, Proline, Prosaro are the 3 newer fungicides with good to very good ratings for head scab. This information can be beneficial for next year.
As far as this year… set your combines to blow as much light weight kernels out the back to reduce the risk of vomitoxins in your wheat. Evaluate your stands to determine the severity of the infection. Some fields may be severe enough to consider a slightly early harvest so as to have time to recoup some losses with a potential second crop…double crop soybeans. Some growers are attempting relay cropping soybeans in fields that are severe as well.
The attached picture is a close up of a normal head of grain and one infected with head scab. As always, please don’t hesitate to call if you have any further questions. The Beck’s Agronomic Staff as well as our highly trained sales staff are here to help you in evaluating your crop and making any needed recommendations.