Ontario Grain Farmer October 2021

36 Agronomy A mycotoxin produced primarily by Gibberella ear rot that devalues grain corn when sold to buyers resulting in price reductions for grain sales. If infected grain is consumed, humans and animals can be negatively affected. • WHAT IS DON (DEOXYNIVALENOL)? Warm (27°C - 28°C), humid, rainy days are ideal conditions for infection when silks are viable at pollination. These conditions were commonly experienced between mid to late July in southern Ontario during the 2021 season. • Infection begins in the ear tip and moves down towards the ear base producing a dark red or pink coloured mould, sometimes it has a whitish appearance from the mycelium, but is usually referred to as pink mould. Toxins produced by Gibberella include DON, ZEN and T-2 toxin. • CONDITIONS FOR GIBBERELLA EAR MOULD INFECTION IDENTIFYING GIBERELLA EAR ROT DON in corn WHAT TO LOOK FOR