Fusarium Head Blight of Wheat Fusarium Head Blight (FHB) • Also called head scab • Caused by the fungus Fusarium – Survives on grass crop residues • Corn • Grain Sorghum • Small grains • Fusarium shown growing on wheat residue in picture to the right Life Cycle of FHB Credit: M. McMullen & S. Zhong North Dakota State Univ. FHB Life Cycle • Wheat is infected at the flowering stage • Environmental conditions required for infection – Free moisture – Temperatures from 75 to 85 F – Source of inoculant • These conditions are less prevalent during flowering west of I-35 than east of I-35 FHB Symptoms • Bleached or white heads with pink or salmon-colored residue • Heads can be partially infected • Other things can cause similar symptoms and be misdiagnosed as FHB – – – – Freeze injury Hail damage Waterlogged conditions Various root rots FHB on some partially-infected wheat heads Partially infected wheat heads on the left and entirely infected head on the right Note the pink/salmon color in the black circle Normally developing grains of wheat FHB-infected grains FHB Consequences • FHB-infected grain can contain compounds called mycotoxins • DON (deoxynivalenol – also called ‘vomitoxin’) is the most common of these compounds • FDA guidelines for use of DON-infected wheat are in the table to the right Use FDA Advisory Level Human 1 part per million (PPM) for Consumption finished grain products for human consumption. No standard for raw grain going into milling process. Cattle over 4 months old 10 ppm (providing grain at that level doesn’t exceed 50 percent of diet). Poultry 10 ppm (providing grain at that level doesn’t exceed 50 percent of diet). Swine 5 ppm (not to exceed 20 percent of ration). All other animals 5 ppm (providing grains don’t exceed 40 percent of diet). FHB Management to Reduce Risk • Crop rotation – rotate to a nonhost crop such as sunflower, soybean, or sesame • Tillage – getting rid of the corn or wheat residue will reduce the amount of inoculant present • Fungicides – triazole fungicides applied at flowering can provide suppression but not complete control Foliar wheat fungicides – 2009 PHIA (days/GS) Leaf rust Stripe rustB Powdery mildew Septoria complex Tan spot FHB_ 4 10.5 VG VG VG VG VG P 4 30 E E G VG VG F Caramba 10-17 30 E E --- --- --- G Proline 5.0-5.7 30 VG --- --- VG VG G Prosaro 6.5-8.5 30 E E G VG VG G 10.5 10.5 E E E E G F-G VG VG E E NR NR E VG E E VG E VG G G VG VG VG VG G E NR NR NR Product TRIAZOLE Tilt Folicur Rate (oz/A) STROBILURIN Headline 6.0-9.0 Quadris 6.2-10.8 MIXED Quilt Stratego TwinLine 14 10 6-11 45 35 30/10.5 APHI = pre-harvest interval; number of days required between last application & harvest ratings from the North Central Regional Committee on Management of Small Grains Diseases; E=excellent; VG=very good; G=good; F=fair; P=poor; NR=no rating. BEfficacy This information is provided only as a guide. It is the responsibility of the pesticide applicator by law to read and follow all current label directions. No endorsement is intended for products listed, nor is criticism meant for products not listed. FHB Management of Harvested Grain • Increase air flow– remove shriveled seed by increasing combine airflow • Clean seed– remove as many small seed as possible by postharvest screening and cleaning • Seed treatment – if seed will be saved for planting, consider applying a seed treatment. The same fungus that causes FHB causes many seedling diseases Summary • FHB requires a specific set of environmental conditions for infection of wheat. • Planting wheat after a non-host crop will greatly decrease the likelihood of infection. • FHB-infected grain may or may not be useable depending on the level of mycotoxins in the grain.