Frost Damage and Sooty Head Molds of Wheat

Alyssa Koehler, Extension Field Crops Pathologist; akoehler@udel.edu

As combining of wheat is coming underway, I have been in multiple fields with frost damage. Level of damage has varied greatly depending on what growth stage the wheat was in during the cold nights of May. Fields in the middle of flowering were the hardest hit. Freezing temperatures at flowering can kill anthers (the male part of the flower) leading to sterility and empty or only partially filled heads. Over the past week, we have observed numerous sooty molds colonizing these frost damaged heads. Multiple fungi can cause sooty molds and they can appear black, white, pink, or green depending on the organism. The most common I have seen this year are the traditional black splotchy look and heads covered in a flakey pink (Figure 1). Sooty molds are typically superficial and while they point to a larger problem of reduced yields due to frost damage, they should have a minor effect on the grain that is there.

Figure 1. Various fungi colonizing frost damaged wheat heads

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