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Poster: Epidemiology: Analytical & Theoretical Plant Pathology


Comparing epidemics of unique Phytophthora infestans clonal lineages with biometrically enhanced spatio-temporal modeling tools
K. MOREY GOLD (1), Z. Zhang (2), D. Rouse (1), A. Gevens (1) (1) University of Wisconsin-Madison, U.S.A.; (2) University of Wisconsin-Madison, U.S.A.

The oomycete Phytophthora infestans causes late blight, a plant disease notorious for giving rise to the Irish Potato Famine of the 1840s. In 2009, a pandemic caused by a newly emerged clonal lineage of P. infestans (US-22) destroyed gardens and small farm tomatoes and potatoes across the US. In the following years, three clonal lineages (US-22, -23, -24) comprised national epidemics, with US-23 predominating from 2013 onward. US-23 is of noteworthy aggressiveness, has small sporangial size compared to previous lineages, and is highly pathogenic on both potato and tomato. Previously, two disease dispersal models were fit using Markov chain Monte Carlo (MCMC) for late blight epidemics in central Wisconsin caused by clonal lineage US-8. In our current work, we validated and enhanced these models using the late blight epidemic caused by US-23 in this region for 2009-2015 and we fit a spatial-temporal semivariogram for both epidemics. Disease data were collected from scouting records of a cooperating crop consultant and were manipulated using ArcGIS and RStudio. The power law model predicted disease dispersion accurately with R2 values between 0.2 and 0.9. Sporangial size greatly influenced dispersion rate which played a role in disease progression. Modeling of specific clonal lineage epidemics in high-risk production regions can aid in developing prescriptive, risk-averse late blight management plans to reduce disease perpetuation and economic loss.