Spatial Pattern Analysis and Sequential Sampling for the Incidence of Leaf Spot on Strawberry in Ohio

Area of Science:

• Plant Pathology
• Agricultural Entomology
• Biostatistics

Background:

• Strawberry leaf spot, caused by Mycosphaerella fragariae (Ramularia brunnea), is a significant disease affecting commercial strawberry production.
• Understanding the spatial distribution of plant diseases is crucial for effective management and control strategies.

Purpose of the Study:

• To quantify the spatial pattern of strawberry leaf spot incidence on commercial farms in Ohio.
• To evaluate statistical models for describing disease frequency and heterogeneity.
• To develop and assess sampling methods for precise disease incidence estimation.

Main Methods:

• Field surveys were conducted on commercial strawberry farms over three years.
• Leaflet disease incidence was recorded from spaced sampling units along transects.
• Beta-binomial distribution and Spatial Analysis by Distance IndicEs (SADIE) were used for data analysis.
• Fixed and sequential sampling curves were developed based on heterogeneity information.

Main Results:

• The beta-binomial distribution accurately described disease frequency in 93% of datasets.
• Disease incidence estimates varied widely, with a median of 0.05.
• Significant spatial autocorrelation and disease clustering were detected in approximately 40% of the datasets.
• Disease clusters extended beyond sampling unit borders in many fields.

Conclusions:

• Strawberry leaf spot exhibits clustered spatial patterns influenced by mean incidence.
• The developed sampling curves provide precise disease incidence estimation.
• These findings support improved disease monitoring and management in strawberry cultivation.