By Harry Brook
Fusarium graminearum is a disease of cereals. It most often affects wheat but can affect barley, and to a lesser extent, oats. It primarily infects the seed in the head as it starts to develop and the spores set up shop in the kernels just as the head is emerging from the stem until the head flowers. This causes some seeds to be chalky and shriveled. It is often called scab or fusarium head blight. Why is it a problem?
There are several species of Fusarium that can cause the typical kernel tombstoning and downgrading of the crop. However, Fusarium graminearum is notable in that it produces high levels of mycotoxins, DON in particular. Deoxynivalenol (DON) is also known as vomitoxin. High levels of DON in feed will cause a reduction in feed efficiency and poor animal performance, particularly in pigs. Allowed levels in feed are set well below where any symptoms would be seen. Severe levels of DON in grain can cause significant loss in value and a problem in marketing the crop.
F. graminearum tends to develop under moist conditions and temperatures around 25˚C or higher. We’ve had these conditions as heads were emerging from the stem. This disease was on the Pest Act, which is used to prevent pests from establishing and spreading in Alberta. However, F. graminearum has been found in trace and greater amounts in Alberta since 1989.
There are some fungicides that can provide some protection to cereal crops but they must thoroughly cover the head as it emerges. Once the flowers on the head are visible, it is too late to spray. Infected seed can be treated but infected kernels will rarely survive to maturity, suffering from seedling blight.
Other provinces, who have had the disease longer, have established maximum allowable levels of Fusarium that can be in their seed. In Alberta, we have a Fusarium Management Plan in place to try to prevent the disease from spreading further.
In early June, the Agriculture minister, Devin Dreeshan, declared his intention to remove Fusarium graminearum from the Pest Act. This will allow individual municipalities to deal with the disease on a local basis. Where it has not been detected, they can have a zero-tolerance policy. Where it is commonly found, a maximum level, allowed in seed, can be set.
Although it has been found in Flagstaff County off and on for a number of years, deregistering this disease from the Pest Act will allow counties the flexibility they need to deal with it effectively.