About

When wheat grain is sold, the Hagberg-Perten Falling Number test is performed to detect starch degradation. Grain with a falling number below 300 seconds is purchased at a discount because starch degradation leads to poor end-use quality. For example, low falling numbers lead to sticky noodles, cakes that fall, and bread that doesn't rise.

Low falling numbers have led to substantial losses for farmers in the Pacific Northwest. Low falling numbers resulted mainly from preharvest sprouting due to rain falling on mature grain in the field in 2011, 2013, 2016, and 2023. However, low falling numbers have also occurred without rain. This can happen as a consequence of cool temperatures during late grain filling. This phenomenon is called late maturity alpha-amylase or LMA. During these years, different wheat varieties exhibited different tendencies towards low falling numbers in response to rain or temperature changes. Please note that the susceptibility of wheat to LMA and preharvest sprouting depends upon conditions at specific times in the wheat life cycle. This is influenced not only by location, but by planting and harvest dates. Thus, the falling number of a line in the variety trial may differ from that of the same variety planted in the same moisture zone.

The purpose of this website is to share some falling numbers data. This website was initiated in 2013 in response to a request from the Washington Grain Commission to make publicly available falling numbers data for varieties from the 2013 and 2014 Washington State University Cereal Variety Trials. This effort has continued, and so far there is data from the 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, and 2023 Washington State University Cereal Variety Trials. To see the data on this website click here.

The falling number test

The Hagberg-Perten Falling Number (FN) test is used to measure damage to the starchy endosperm as a consequence of amylase enzyme action. This method is based on the fact that a slurry of wheat flour in water will gelatinize upon boiling – just like making gravy. Starch chains cleaved by alpha-amylase fail to gelatinize well. The more alpha-amylase in the sample, the faster the stirrer falls, the lower the falling number. Bakers prefer a falling number above 300. While bakers can add alpha-amylase to their dough if the falling number is high, they cannot remove alpha-amylase once it is there. Also, bakers like to have a consistent product. Keep in mind that a small increase in alpha-amylase content has a big effect on falling numbers and quality – so it is unwise to mix sprouted grain with sound because it will just compromise the quality of the sound grain. For example, mixing equal amounts of grain with a falling number of 100 and a falling number of 400, will result in grain with a falling number much lower than 250. This video from Perten Instruments demonstrates the falling number method.

Some observations

It is possible to form hypotheses as to the causes of low falling numbers in the WSU Cereal Variety Trials in recent years. Our hypotheses were formed by comparing weather data from AgWeatherNet and other sources to the time when the wheat was likely susceptible to LMA and sprouting based on the average heading date and harvest date of each location. Our views are as follows.

2013. Preharvest sprouting occurred in Colton, Fairfield, Mayview, Pullman, Reardan, St. John, and Lamont for winter wheat, and in Endicott, Fairfield, and St. John for spring wheat. Potential LMA events occurred in Mayview, Moses Lake, and Walla Walla.

2014. Preharvest sprouting occurred in Almira, Anatone, and Fairfield. Potential LMA events occurred in Bickleton, Connell, Moses Lake, and Ritzville.

2015. Preharvest sprouting occurred in Pullman. It is difficult to determine the cause of low FN at the remaining locations. The Phadebas(R) Amylase Test revealed that some samples with FNs below 300 sec did not show alpha-amylase enzyme levels consistent with induction by preharvest sprouting or LMA. We speculate that some of the low FN in 2015 may have been due to the fact that kernels were shriveled as a result of heat stress and thus had low starch content. Thus, 2015 data must be interpreted with caution.

2016. 2016 had the most widespread problems with low falling numbers. Low falling numbers were due largely to LMA, but also resulted from preharvest sprouting. There was a mixture of both problems at many of the same locations.

2017. Problems with low falling numbers were observed only at a limited number of locations. Falling numbers were examined mainly in locations that had low falling numbers in highly susceptible cultivars. As in 2015, some of the low falling numbers were not associated with elevated alpha-amylase.

Additional information

A summary of current research by Washington State University and USDA-ARS on the topic of late-maturity alpha-amylase (LMA) and falling numbers appears in the November 2017 Wheat Life article All hands on deck by Camille M. Steber and Kimberly Garland Campbell. This March-April 2017 Crops & Soils Magazine article, "Avoiding problems in wheat with low Falling Numbers", by Camille Steber, provides general information about managing falling numbers. This August 2016 Washington State University Extension article, entitled "Managing the Risk of Low Falling Numbers in Wheat" answers frequently asked questions about falling numbers in wheat production. Some additional information can be found in the Wheat Life article Preventing those falling number blues from 2013, and the Wheat Life article Falling numbers: research strategies to stay out of the red from 2014, by Camille M. Steber, Arron H. Carter and Michael Pumphrey.

Funding

Washington Grain Commission (Projects 7599, 7336, 5389, 5333, and 3690) funded falling numbers testing of the WSU Cereal Variety Trial from 2013 through 2016 in a collabortaion with Washington State University and USDA-ARS. The USDA-ARS has funded falling numbers testing of the WSU Cereal Variety Trials as a collaboration with Washington State University since 2017. One goal of the project is to provide farmers and breeders with information about the falling numbers of released and experimental lines. Another goal of the project is to select for genetic material with robust falling numbers within the spring and winter wheat breeding programs. Thus many breeding and mapping lines are being tested for falling numbers, LMA, and preharvest sprouting susceptibility. These data do not appear on this website.

People

The principal investigators of the Washington Grain Commission and USDA funded projects that generated FN data were Camille M. Steber (USDA-ARS), Michael O. Pumphrey (WSU), and Arron H. Carter (WSU), and Kimberly Garland Campbell (USDA-ARS). Major collaborators included Clark Neely (WSU Cereal Variety Trial), Stephen Guy (WSU Cereal Variety Trial), Ryan Higgenbotham (WSU Cereal Variety Trial), Alison Thompson (USDA-ARS), Alecia Kiszonas (USDA-ARS), Craig Morris (USDA-ARS), and Douglas Engle (USDA-ARS). The lead technician obtaining the falling numbers data is Abigail Holtz (USDA-ARS) with the assistance of Rehana Parveen (WSU), Spencer Matley (WSU), and Grant Irey (WSU). In the past falling numbers testing has been performed by Galina Mikhaylenko, Brooklyn Schumaker, Drew Bowdish, Julia Jitkov, Tracy Harris, Rehana Parveen, Sarah Peery, Xavian Thompson, Allie Druffel, Courtney Broedlow, Samantha Beck, Robert DeMacon, Carissa Corrigan, Kristofor Ludvigson, Jason Wigen, and Rylee Suhadolnik. WSU graduate students working on other aspects of the project have included Shantel Martinez, Keiko Tuttle, Stephanie Sjoberg, Chloe Chang Liu, Sarah Peery, and Jason Wigen.