Pythium seedling blight, which can be caused by a number of Pythium spp., is a disease that affects soybean (Glycine max) in the United States and Canada. Pythium ultimum var. ultimum, one of the most common pathogenic species, is favored by cool, wet conditions in early spring and causes seed decay, root rot, and seedling damping-off. In all, 102 major ancestors of modern North American cultivars and "first progeny" cultivars developed directly from ancestral lines were evaluated for resistance to P. ultimum var. ultimum and two other species of Pythium in greenhouse assays. Several ancestors and first progeny cultivars, as well as the resistant check Archer, had varying levels of partial resistance to an Illinois isolate of P. ultimum var. ultimum. In a subsequent experiment, four of the most resistant lines (PI 84637, Maple Isle, Fiskeby III, and Fiskeby 840-7-3) and the susceptible cultivar Kanro were screened for resistance against isolates of P. irregulare and P. sylvaticum, and resistance to P. ultimum var. ultimum was confirmed. The lines that were partially resistant to P. ultimum var. ultimum in the first experiment were also partially resistant to P. irregulare and P. sylvaticum. The P. ultimum var. ultimum isolate was the most aggressive of the three isolates, followed by the P. irregulare and P. sylvaticum isolates. Modern cultivars descended from the soybean lines with partial resistance to these pathogens could be useful sources of resistance to Pythium seedling blight if they are found to have similar levels of resistance.

Fusarium graminearum, the major causal agent of Fusarium head blight (FHB) of wheat (Triticum aestivum) in the U.S., can produce mycotoxins, such as deoxynivalenol (DON), during infection. Contamination of wheat grain with DON is a major concern for wheat producers and millers, and the U.S. Food and Drug Administration (FDA) has set advisory levels for DON in finished wheat products for human and animal consumption. Practices utilized to manage FHB and DON contamination include planting wheat cultivars with moderate resistance to FHB and applying efficacious fungicides at the beginning of anthesis. Under severe epidemics, DON contamination can exceed FDA advisory levels despite implementation of these measures. Additionally, fungicide efficacy can be limited when anthesis is not uniform among plants in the field, which can occur when planting is delayed or if there is non-uniform seedling establishment. The objectives of this study were to evaluate the effect of (1) in-furrow phosphorus application at planting and seeding rate on heading and anthesis uniformity, FHB symptomology, DON contamination, grain yield, yield components, and test weight; and (2) harvesting at different grain moisture concentrations on FHB symptomology, DON contamination, grain yield and test weight. Field trials were established in Princeton, Kentucky, from 2017 to 2019, to evaluate in-furrow phosphorus application at planting (0 kg P 2 O 5 ha-1 and 47 kg P 2 O 5 ha-1); seeding rate (377 live seeds m-2 and 603 live seeds m-2); and grain moisture at harvest (20 to 22% and 13 to 15%). In-furrow phosphorus increased grain yield and spikes m-2 , but had no effect on heading and anthesis uniformity or DON contamination. The 603 live seeds m-2 seeding rate decreased the number of days to Zadoks 60 for the November planted wheat, and decreased FHB incidence, but did not decrease DON contamination. Harvesting at 20 to 22% grain moisture decreased Fusarium damaged kernel ratings and percent kernel infection but increased DON contamination in the harvested grain. Although in-furrow phosphorus, seeding rate, and harvesting 20 to 22% grain moisture did not decrease DON contamination, there is potential for these treatments to alleviate negative effects of late planted wheat grown in stressful environments.

Core ideas (3-5 impact statements, 85 char max for each)  Maturity group effected seed yield, yield components and protein concentration  Seeding rate effected seed yield, seeds m-2 , V2 and R8 plant populations  Greatest yield of each maturity group was attained with the highest seeding rate  The longest adapted rMG and higher seeding rates had the greatest net benefits

Double-crop soybean [Glycine max (L.) Merr.] production in Kentucky involves planting soybean after soft red winter wheat (Triticum aestivum L.) harvest during June and July. Double-crop soybean yields are lower than full-season soybean yield planted earlier in the spring. This research aimed to determine the effect of seeding rate, seed treatment, and applying foliar fungicide and insecticide at the R3 growth stage at two planting timings on double-crop soybean seed yield, yield components, and seed quality. Field trials were established in Princeton, KY, in 2017, 2018, and 2019 after wheat harvest. Planting double-crop soybean early, after wheat was harvested at 20 to 22% grain moisture, resulted in increased seed yield, seeds ft -2 , and protein concentration compared with double-crop soybean planted later. A seeding rate of 225,000 seeds acre -1 resulted in increased seed yield, seeds ft -2 , and seed protein concentration compared with 150,000 seeds acre -1 . A seed treatment including fungicides and an insecticide did not impact seed yield, yield components, or seed protein or oil concentration compared with no seed treatment. Applying a prophylactic foliar fungicide and insecticide treatment at the R3 growth stage increased seed yield and seed mass compared with an economic threshold application. In addition, the most intensive management (225,000 seeds acre -1 , seed treatment, and prophylactic fungicide and insecticide) yielded ∼25% more than the base treatment and had more seeds ft -2 . The results are the first to indicate the potential for intensive management practices to increase double-crop soybean productivity in Kentucky.

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