Pre-harvest Sprouting and Falling Number

a close up image of wheat head exhibiting early sprouting

Persistent rainfall over the last several days has prevented some wheat fields from being harvested. This could lead to pre-harvest sprouting and other grain quality issues. However, the extent to which sprouting occurs will depend on the variety and how long the grain is exposed to warm, wet conditions before it is harvested. For instance, white wheats tend to be more susceptible to pre-harvest sprouting than the red wheats commonly grown here in Ohio. As a result, the level of sprouting will vary from one field to another. Sprouting is a trail that negatively affects grain quality. It actually is premature germination of the grain while it is still in the heads in the field. This process is driven by enzymes, including α amylase, and the activity of this enzyme can be measured to determine how bad pre-harvest sprouting it. See: for more on delayed grain harvest and grain quality. 

Falling number (FN in seconds) is a widely accepted measure of pre-harvest sprouting damage. The higher the FN, the lower the level of sprouting. As a guide an FN ≥ 300 sec would indicate that the grain is not sprouted, 200 ≤ FN < 300 sec would be indicative of some sprouting, 62 < FN < 200 would indicate that the grain is severely sprouted, and FN = 62 would mean that the grain is extremely sprouted. However, PLEASE NOTE that the specific numbers and ranges will depend on the equipment used to measure FN, and what the numbers mean in terms of utilization of the grain, depends on the intended end use. So, a grain buyer has some freedom to determine what he or she would consider to be an acceptable FN.

Falling number measures the time (in seconds) it takes for a weighted plunger to fall through a suspension of heated flour paste. In other words, it measures the thickness (viscosity) of the heated flour paste made from the grain being tested. Flour paste made from badly sprouted grain is thinner (less viscous) than paste made from healthy, unsprouted grain. As a result, the plunger taking less time to fall through the flour paste from sprouted grain, hence the lower falling number.   

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.