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Relationship between soil health indicators and potato early-die in Michigan

George Bird: Michigan State University

<div>Potato early-die (PED) caused by the joint action of Pratylenchus penetrans and Verticillium dahliae is a limiting factor in potato production in Michigan. The objective of this research was to identify the relationships between soil health indicators and PED. Two 50-acre potato fields were used. The Defender was a conventional two-year rotation with potato (2015, 2017) and seed corn (2014, 2016, with soil fumigation and a biological nematicide. The Challenger had one cash crop (potato in 2015, 2017) and cover crops (2014, 2016), pearl millet (2014) and cover crop blends (2016). Annual soil samples from 32 permanent geo-positioned sites were analyzed for twelve soil health indicators, nematodes, bacteria, tuber yields and aerial NDVI (vegetative index). Mean Defender tuber yields were 371 cwt/A in 2015; whereas, Challenger yields were 293 cwt/A. 2016 soil health and NDV indices were greater for the Challenger than the Defender. The 2016 NDVI was superior for a four cultivar cover crop blend, compared to a seven species blend. The 2016, bacteria DNA sequences identified 28 phyla, 81 classes, 140 orders, 300 families and 814 genera. Sequence assignment was dominated by 9 of the 28 phyla recovered, comprising nearly 96% of the total bacterial community assemblage and present in all GPS locations. Every sample contained known beneficial bacterial taxa including Proteobacteria, Acidobacteria, Actinobacteria, Verrucomicrobia, Firmicutes. The greatest 2017 tuber yields were associated with the 2016 four cultivar cover crop blend and the aerial NDVI. The highest 2017 P. penetrans populations were associated with the greatest tuber yields.</div>