The reduced amount of inoculum produced in 2002 will help decrease the amount of inoculum present in future years. However, if Fusarium was has been a problem in your area, you are still at risk for subsequent infections. Once the fungus is in the area, it is there to stay. The fungus causing FHB survives in the soil, straw and residue as well as native grasses and forage crops. Last season's drought will help to diminish the level of potential infestation, but the areas with the greatest incidence of Fusarium tended to be the areas that had adequate precipitation. While the absence of drought in these areas was generally a good thing, it did create conditions that favour the survival of the inoculum.
Fusarium graminearum can produce wind borne spores that spread an unknown distance. The march westward of these spores is blamed for the recent infestation in Saskatchewan. Conditions favourable for a large production of spores in the 1980's expanded the infected area to include many parts of eastern Saskatchewan. The expansion or contraction of the F. graminearum affected area through spore transfer will depend on future Fusarium levels and spore production.
An adverse side effect of the drought was to create a seed and feed shortage. Areas that were able to harvest the affected crops were generally areas where F. graminearum has been present. Introducing F. graminearum into areas previously unaffected by FHB through feed or seed can create the potential for infection to occur and spread into previously unaffected areas.
The shortage of feed has caused livestock producers to import feed. The imported seed and foliar material can contain F. graminearum inoculum. While not the most desirable feed source, feed shortages and price discrepancies may require using the infected material. Fusarium infected material that passes through a ruminating animal will be killed. However, the risk of subsequent infection occurs with wasted feed that doesn't pass through the cattle's digestive system. Special care in handling the feed in unaffected areas should occur. Clean up and dispose of spills by composting the material at 60 to 70 degrees for two weeks.
Fusarium reduces feed quality. While the toxin produced by F. graminearum is comparatively harmless, it can cause animals to go off their feed. Non-ruminants are particularly sensitive to the presence of DON. Agriculture and Agri-Food Canada guidelines are 1 ppm for swine, dairy cattle and horses and 5 ppm for growing beef cattle, sheep and poultry. The Federal Health Protection Branch allows 2 ppm of DON in uncleaned soft white winter wheat and 1 ppm in uncleaned soft white spring wheat intended for infant foods. A suspicion of Fusarium mould in malting barley can lead to rejection. Several malting companies have a zero tolerance for DON in barley.
Using infected cops for seed can quickly introduce inoculum into a previously unaffected area. Grain with a high level of infection isn't suited for seed use, but lower level infections are possible to use for seed. The decision whether to use infected seed or not should be based on the infection history of your area. In general SAFRR recommends:
Penny Pearse, Provincial Plant Disease Specialist, SAFRR