Epidemiolgy of boxwood blight in western North Carolina and Virginia and validation of the boxwood blight infection risk model.

The goal of this project is to investigate the field epidemiology of boxwood blight in western North Carolina and Virginia and validate the latest Boxwood blight infection risk model with field data.

Abstract

Boxwood blight is a highly invasive emerging disease. Since the first US report in North Carolina and Connecticut in 2011, boxwood blight has spread to over 30 US states, risking more than 90% of boxwood production. A boxwood blight infection risk model was developed from limited studies in controlled environments as disease field epidemiology was largely unknown. Our study investigated the disease field epidemiology and validated the model’s prediction using leaf wetness estimated by leaf wetness sensor or algorithms by analysing weekly blight monitoring data collected on detector plants exposed to the prevailing environmental conditions from spring through fall of 2014 to 2017. Boxwood blight was recorded in 61 of 86 weeks, with the highest infected leaf count recorded in late summer or early fall. Rainfall, high relative humidity outside rainy periods and optimal temperatures during prolonged leaf wetness had a significant positive effect on boxwood blight development. Classification analyses showed that predictions from the model using leaf wetness estimated by leaf wetness sensor were more closely aligned with observations from the field. This study improved our understanding of disease field epidemiology, provided leads to improve the existing model, and generated essential knowledge for formulating effective strategies for blight mitigation.

Reproducibility and data availability

This analysis is packaged and fully reproducible. All data from this work are included in this repository in the “inst/extdata” folder. Code used for importing data, data munging, visualisation and model fitting are available to run in R Markdown vignettes, including extra instruction for which we did not have space in the paper. A user-friendly website of the research compendium can be accessed via this link https://ihsankhaliq.github.io/epiboxwoodblight/ where the vignettes can be accessed under the “Articles” menu item. The archived code and data are available at https://doi.org/10.5281/zenodo.12594039