Higher aggregation of Cercospora leaf spot is a common spatial pattern in table beet fields in New York

Authors: HECK, DANIEL - Cornell University; KIKKERT, JULIE - Cornell University; Hanson, Linda; PETHYBRIDGE, SARAH - Cornell University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/30/2020
Publication Date: 7/20/2020
Citation: Heck, D.W., Kikkert, J.R., Hanson, L.E., Pethybridge, S.J. 2020. Higher aggregation of Cercospora leaf spot is a common spatial pattern in table beet fields in New York [abstract]. Northeastern Division of the American Phytopathological Society. 110(7S):S31. https://doi.org/10.1094/PHYTO-110-7-S1.27.
DOI: https://doi.org/10.1094/PHYTO-110-7-S1.27

Interpretive Summary:

Technical Abstract: Understanding how diseases are distributed in fields is the first step to develop efficient management strategies. Cercospora leaf spot (CLS), caused by Cercospora beticola, is the most common foliar disease in table beet fields in New York. The causes crop loss by reducing green leaf area and foliar health and deleteriously affecting the ability to harvest by top-pull machinery. The objective of this study was to analyze the spatial pattern of CLS in table beets fields in New York. Disease assessments were performed in 2017 (N = 16 fields) and 2018 (N = 15 fields). In each field, three transects with 51 sampling locations were evaluated. The sampling locations were separated by 0.3 m within each transect and 100 m between transects. Six leaves at each sampling location were assessed for the presence or absence of CLS symptoms. Incidence was calculated based on the number of diseased leaves in each sampling location. Maps were constructed to visualize the distribution of diseased plants in fields and spatial pattern analyses were used to quantify the degree of aggregation. Incidence ranged from 16.6 to 74.2%, with a median of 30.1%. Fisher´s aggregation index (D) for binomial data detected aggregation in all fields (D > 1; P < 0.001). D values ranged from 1.88 to 4.69 with a median of 3.94. Aggregated patterns were also detected by ordinary and median runs analyses for 38.7% and 51.6% of the fields, respectively. Autocorrelation analyses demonstrated significant correlation between diseased plants up the 5th spatial lag (~ 1.52 m) within most fields. Results of this study demonstrate that CLS is highly aggregated within table beet fields in New York. This information can be used as a primer to develop new hypothesis surrounding pathogen dispersal, sampling programs, assessment of crop losses and more efficient management strategies.