Symptoms of Fusarium graminearum on cereal grains
When driving down a country road on a bright afternoon and gazing out into a sea of rippling wheat, one might be deceived by the picturesque front, not realizing how the individual grains within that field may start suffocating from an aggressive fungal disease: Fusarium head blight (FHB), also known as scab.
FHB can be detrimental to wheat, causing grain to have low test weights, lost yield, low germination and mycotoxin contamination.
FHB can display disease symptoms, as we discuss below. But it can also be present in a field, harming the crop and yield before symptoms are even visible and the disease can be identified.
When scab is visible in the crop, the primary symptom is the bleaching of some florets before they reach maturity.
This causes sterile flowers which produce kernels that have a shrunken, chalky, white appearance. This appearance has earned them the industry moniker of "tombstones."
The Fusarium pathogen that causes scab isn’t unique to wheat. In fact, it causes disease in other crops, too, such as corn, and it can overwinter between crops among field stubble. This means that crop rotation practices often used to manage worm and insect pests aren’t effective when it comes to FHB.
For example, explained Jason Manz, cereals marketing manager, Crop Science, if a field of corn is infected with Gibberella stalk rot, that same pathogen can overwinter and appear as scab the next year in wheat planted to the same field. Plant that field back to corn the following year, and the cycle continues.