Kentucky is often described as belonging to the Upper South or the Southern Corn Belt; in other words, it does not fit naturally into standard geographies.  Situated just below the Mason-Dixon Line, Kentucky is the epicenter of doublecropping, in which growers produce 3 crops in 2 years: corn is planted no-till in the spring and harvested in September; wheat is sown without tillage directly into corn stover in October and harvested in June, with soybean drills following closely behind wheat combines to plant “doublecrop beans”.  This profitable rotation puts the SRW wheat crop at risk for FHB every year.  Our resistance breeding approach has relied heavily on phenotyping breeding lines and cultivars in a mist-irrigated nursery, inoculated with grain spawn. In 2016, however, the UK Wheat Breeding Program began to use genomic selection (GS) for FHB, agronomic and quality traits. Initially, we simply added GS to the protocol we had previously followed, testing preliminary lines in an augmented design at one or two locations.  After determining the augmented design was no more predictive of future performance than GS, we began to use GS alone at the preliminary line stage in 2021.  F_3:4 headrows are selected phenotypically and remnant seed is genotyped with genome wide markers. Genomic predictions for F_4:5 progeny are generated using the genomic data coupled with phenotypic data from field-tested lines (the training population) related to the F₄ lines.  Selections are ultimately based on genomic predictions with some attention to phenotype – height, maturity, vigor, clean leaves. Genomic predictions have been very useful for FHB resistance breeding: from 2019  - 2022, weather during the infection period made it impossible to create an epidemic in the irrigated scab nursery.  Genomic predictions for FHB index and DON were used in guiding selections for resistance.  In 2023 and 2024 we compared predictions developed from two very diverse sets of training populations: one set associated with Sungrains, a consortium of southern states, the second set with Norgrains, a consortium of northern states.  Differences between the two sets of predictions were abundant, but certain parents were present in the pedigrees of top performing lines from both sets of predictions.

Acknowledgment

This report is based on work supported by the USDA, under agreement no. 59-0206-9-54. This is a cooperative project with the US Wheat and Barley Scab Initiative. Any opinions, findings, conclusions, or recommendations expressed are those of the authors alone.