Integrated Fusarium head blight management: Employing all the tools

Fusarium head blight continues to be of significant economic concern in Ontario as well as other provinces. Although new tools have helped, it is not realistic to expect a single cultural or management practice to effectively manage this devastating disease alone. The integration of the various cultural or management practices (“tools”) into a coordinated FHB management program can minimize producer losses and risk. The components of an integrated FHB management program include: (1) seed quality, (2) seed treatment, (3) variety selection (tolerant/resistant), (4) crop rotation, (5) disease forecasting and fungicide application, (6) residue management, and (7) harvest management.

(1) Seed Quality – Begin by planting good quality seed that is free of Fusarium. Although seed infection is not considered a primary inoculum source for late season head blight, the use of infected seed has been shown to reduce seedling emergence, vigour and tillering. Infected seed increases the survivability of the fungus from one year to the next and is a potential means of spreading or introducing Fusarium into previously non-infected fields or new wheat producing areas.

(2) Seed Treatment – Fungicide seed treatments are effective against many seed-borne and soil-borne seedling blights and seed rots and therefore are a recommended practice. The use of these products on scab affected wheat can increase germination, emergence, and tillering and thereby limiting stand losses due to Fusarium seedling blight. Seed treatments will not prevent late season FHB from developing.

(3) Variety Selection – Although, no truly resistant wheat varieties are presently available, public and private breeding programs have made significant progress in the development of varieties with partial resistance or “tolerance”.

(4) Crop Rotation – Rotation of non-host crops will reduce FHB levels. Avoid planting small cereals following other small cereals or corn. Two years between small grain or corn crops will allow for residue decomposition. Rotation will not eliminate the disease since inoculum from neighbouring fields still pose a risk.

(5) Disease Forecasting and Fungicide Application – Various Fusarium head blight or DON Prediction Models such as DONcast have been developed. Although, these models provide a new and effective “tool” for managing and timing fungicide applications for FHB, they do not replace good old fashion scouting. The emphasis on weather data requires knowledge of the local (field) weather conditions and crop development. Fungicide efficacy is dependent on delivery systems (coverage) and variety susceptibility. A number of new fungicides such as Caramba, Proline and Prosaro are available and have provided more consistent control of Fusarium head blight and DON over Folicur. Remember Fusarium head blight timing starts at Day 0 which occurs when 75% of the heads on the main stems are fully emerged. Target your spray applications for Day 1 to Day 4, with optimum timing of Day 2 although with these new fungicides the window maybe extended to Day 6-8.Understanding the parameters that make these prediction models work and how the various components interact is necessary for successful implementation and management of Fusarium head blight.

(6) Residue Management – Infested cereal (including corn) residues are a primary source of inoculum. The longer infested residues remain intact on the soil surface, the greater potential for disease development. Removal of residues will reduce inoculum levels but tillage on its own will not eliminate the disease. In areas with a history of the disease, inculum production from surrounding fields could led to Fusarium head blight development under favourable environmental conditions.

(7) Harvest and Storage Management – Grain sample improvements are possible at harvest through simple adjustments to the combine. Increasing air blast velocity (speed) will remove many of the smaller, lighter Fusarium infected kernels. Although a small amount of healthy kernels will be removed, the improvement in sample grade will off set these losses. Reducing combine ground speed and adjusting cleaning sieves can further separate out infected kernels. Proper storage and drying will limit further Fusarium development after harvest. Check stored grain frequently to ensure that the grain stays in good condition.

Reducing producer risk and economic losses to FHB requires the integration of available cultural and management “tools” or practices into a sustainable program.