Stem rot of rice in California: incidence-severity relationship, yield impacts, and fungicide management.
Data files
Jul 31, 2026 version files 35.61 KB
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README.md
2.92 KB
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SR_data_DRYAD.csv
32.69 KB
Aug 06, 2026 version files 35.56 KB
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README.md
2.88 KB
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SR_data_DRYAD.csv
32.69 KB
Abstract
Stem rot, caused by Sclerotium oryzae, is a common and important disease of rice grown in California. This study used 19 stem rot fungicide trials conducted between 2017 and 2024 in the Sacramento Valley of California to determine the relationship between disease incidence and severity. Eighteen of these trials were used to estimate the impact of stem rot severity on grain yield and seven to evaluate the best timing of application for the azoxystrobin containing fungicides Quadris and QuiltXcel. Results show that incidence and severity are related and that incidence up to values of 90% can predict the severity of stem rot up to a severity index value of 2. Yield loss due to stem rot severity was found to be described best by a linear model including yield level as a factor, with a rate of yield loss of 258 kg/ha (95% CI: 193 to 325 kg/ha) for each unit change in stem rot severity index. Relative yield loss per unit increase in severity index was calculated to be 2.63% (95% CI: 1.95 to 3.3%). The azoxystrobin containing fungicides Quadris and QuiltXcel reduced stem rot severity when applied at the boot stage but not at tillering. Application of Quadris at boot or QuiltXcel at heading resulted in significant yield increases.
Dataset DOI: 10.5061/dryad.j3tx95xxf
Description of the data and file structure
The data originate from 19 fungicide trials conducted between 2017 and 2023 in the Sacramento Valley of California. Each trial consisted of 3x6 m plots established in a randomized complete block design with at least four replications. Treatments consisted of an untreated control and application of different fungicides. Stem rot incidence and severity were determined at drain time before harvest. Using a small plot combine all but one trial were harvested. Rice variety M-206 was used in 18 trials and M-209 in one trial. Cells with N/A represent missing values (trial or plots could not be harvested, lost data, etc). Cells with "null" represent treatments of trials that were not used in the fungicide comparison analysis.
Files and variables
File: SR_data_DRYAD.csv
Description: This file includes all data
Variables
- Trial: Trial number.
- Treatment: This is the original treatment number for each trial. It shows the total number of treatments used in each trial. It is not used in the analyses.
- Treatment_1: This is the recoded treatment number used in the fungicide comparison analysis for the selected trials where the fungicides of interest were used. 1=untreated, 22=Quadris at tillering, 23=Quadris at boot, 24=Quadris at heading, 25=QuiltXcel at tillering, 26=QuiltXcel at boot, 27=QuiltXcel at heading. Cells with "null" represent treatments of trials that were not used in the analysis.
- Rep: Replication number for each treatment
- SR_Inc: Stem rot incidence, expressed as proportion.
- SR_Sev: Stem rot severity index. Tillers in a sample were classified into one of five severity classes (0-4), where 0 is no disease and 4 is tiller rotted through. To calculate the stem rot severity index, each class was multiplied by the number of tillers in that class, all the products summed, and the result divided by the total number of tillers in the sample. Each sample was between 30 and 50 tillers.
- Yield_kg: Grain yield in kg/ha at 14% moisture content.
- Year: Year when trial was conducted
- Variety: Variety used in trial. 1=M-206, 3=M-209.
- Disease_level: Trials were classified as belonging to one of two disease levels. 1=disease index in untreated plots below the median disease index in untreated plots for all trials (1.88), 2=disease index in untreated plots as being above the median disease index in untreated plots for all trials (1.88)
- Yield_level: Trials were classified as belonging to one of two yield levels: 1=average yield in the trial below the median yield of all data (9,861 kg/ha), 2=average yield in the trial above the median yield of all data (9,861 kg/ha)