The main focus of his research during this time period was developing crop cultivars resistant to early snap frosts, droughts, and lengthy cold temperatures, which were all conditions important to farmers in the state.

He determined that frosts were of the greatest concern in killing crop fields and so sought to make cultivars of tomatoes and corn with higher resistance to sudden extreme lower temperatures.

While Yeager was not affected by this incident, he was concerned about the ongoing budget cuts to scientific research and what had happened among the faculty, resulting in him resigning on September 30, 1937.

[4] Both the President, John West, and Dean, Archibald Minard, of the university tried to convince Yeager to return to his position with his full research space and funding provided and protected against future decreases.

But before he and his family moved away from Fargo, Yeager released a highly critical editorial of his own in The Forum, debasing the university for the lack of support of its employees and of allowing "some politician" to hold sway over its activities.

Yeager remained at Michigan State for several years, before taking a Horticultural Department head position at the University of New Hampshire in 1939, where he would stay until his retirement in 1959.

[6] The research of H. O. Werner as the university horticulturalist before him served as the template for Yeager's work, and he aimed to create a cultivar of sweet corn that was better than even the Golden Bantam, the most popular variety at the time.

Making attempts at hybridization with Gill's Early Market variety, he finally succeeded in creating a worthwhile enough cross in 1923, though had to go through another round of replantings to have enough seed in 1924 to send out to farmers for testing in the 1925 season.

[7] Another crop that Yeager began investigating was sweet potatoes thanks to their high nutrient levels, but determined that the growing season of North Dakota was too short for any hybrid cultivar or other trait improvement to overcome.

[4][8] Yeager's early work at the University of New Hampshire starting from 1936 focused on producing minuscule "midget" watermelons for easier public consumption.

He ultimately triumphed in 1950 in making the New Hampshire Midget cultivar, which was a hybrid cross of the Dakota Sweet from Russia and the Favorite Honey from Japan.

It took over a year and multiple generational trials to make the recessive golden rind consistent and to have other traits that allowed the melon to grow within 70 days.

[12][13] The agricultural experiment stations and their researchers were tasked with releasing periodic bulletins on farming and horticultural practices and methodologies, either generally or for specific crops.

[6] Throughout his academic work, he became friends with several other notable individuals, including the owner of the Bismarck seed company George Will, the "Flower Lady of North Dakota" Fannie Mahood Heath, and fellow researcher from Canada W. Russ Leslie.