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

Credit: M. McMullen & S. Zhong North Dakota State Univ. Life Cycle of FHB

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 UseFDA Advisory Level Human Consumption 1 part per million (PPM) for 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). Poultry10 ppm (providing grain at that level doesn’t exceed 50 percent of diet). Swine5 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 non- host 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 Rate PHI A Leaf Stripe Powdery SeptoriaTan Product(oz/A) (days/GS)rust rust B mildew complex spot FHB_ TRIAZOLE Tilt VG VG VGVG VG P Folicur 4 30 E E GVG VG F Caramba E E G Proline VG VG VG G Prosaro E E GVGVG G STROBILURIN Headline E E GVG E NR Quadris E E F-GVG E NR MIXED Quilt E E VG VG VG NR Stratego VG VG G VG G NR TwinLine /10.5 E E GVG E NR A PHI = pre-harvest interval; number of days required between last application & harvest B Efficacy 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. 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 post- harvest 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.