The White Mold Forecaster
The purpose of Sporecaster is to assist farmers in making management decisions for white mold in soybean.
The best time to manage white mold is during flowering (R1 and R2 growth stages) when apothecia (small, mushroom-like structures) are present on the soil surface. Apothecia release spores which infect senescing soybean flowers, leading to the development of white mold.
University research has indicated that the appearance of apothecia can be predicted using several variables including weather and amount of soybean row closure in a field. Based on this research, Sporecaster models have been developed to forecast the risk of apothecia being present in a soybean field. Farmers can easily input site-specific information about their soybean field into the app, which combines field information with the research-based models to predict the best timing for white mold treatment in that field.
Sporecaster uses GPS coordinates to determine if weather has been favorable for the development of apothecia during soybean flowering in a specific field. Models in the app use 30-day averages of maximum temperature, relative humidity, and maximum wind speed to predict favorable conditions for most soybean growing regions. Based on these predictions and crop phenology, a site-specific risk prediction is generated for three scenarios (non-irrigated soybeans, soybeans planted on 15″ row-spacing and irrigated, or soybeans planted on 30″ row-spacing and irrigated).
Sporecaster is designed to predict the probability of white mold apothecial presence. However, fields still need to be scouted to determine if the soybean crop meets thresholds such as canopy closure and presence of flowers.
To use the Sporecaster app, download it onto your phone from the Apple Store or Google Play. The app allows the user to locate and setup multiple fields and run the apothecial risk prediction model using weather data from a third-party provider (Dark Sky API).
Once opened, you can create Fields and determine their apothecial risk. The app will prompt the user for information, such as field name, row spacing, if the field is irrigated and the field location. Then the risk of apothecial presence can be calculated. The model will only run if it is told that flowers are present and if canopy closure meets threshold (for 30-inch row spacing only). A forecast risk expressed in percentage units is then shown, with red being above the 40 percent action threshold for a fungicide application. It is possible to rerun the model as desired and even go back to previous years to examine previous risk.
The first step to create a new white mold risk forecast is to enter field information. This includes field name, row spacing, GPS location, and irrigation status. Use ‘Tap to select a location’ to open the map or enter custom GPS coordinates using the text input. You can use road or satellite view on the map; then tap ‘Done’. Next tap ‘Save’ and the field information will be saved in your ‘Field List’.
The forecast screen is displayed next, where flowering information is required to progress. The forecast models only run when you indicate that at least one soybean flower is present. Generally, the optimum time to run the models is between flowering and beginning pod (R1-R3 growth stages), however, flowers can be present even into full pod (R4 growth stage) on some varieties in some environments.
On 30″ rows, sufficient canopy closure is needed for the formation of apothecia. Roughly 40% closure between rows is required for apothecia to develop. The forecast models only run when canopy closure of 40% or more (Over threshold) has been selected in the app. Pictures in the app will guide this choice.
Choose a date for the forecast. The calendar defaults to the present date. Choose any day previous to this date to run historical risk calculations. You can also choose one or two days in the future; but be aware such forecasts are less accurate due to rapid changes in weather. Also, the models only run when the app is able to connect to the internet and download a complete 30-day set of weather for the field’s GPS location.
If Sporecaster predicts high risk (a red indication is displayed) in your area for your planting scenario, a fungicide application would be recommended. If medium risk (yellow indication in displayed) is predicted, consult Sporecaster again over the next few days to monitor the situation. High risk scenarios can develop quickly. If low risk (blue indication in the display) is predicted, then infection is not likely. However, Sporecaster should be consulted again in a week during soybean bloom (R1 and R2 growth stages) to monitor the situation.
There are two buttons at the top of the forecast screen that will show a history of past forecast results and will create an email containing the risk forecast(s) for a field that can be shared for further record keeping or management.
If a field receives a High Risk prediction using Sporecaster, we recommend consulting your local Extension personnel or resources for the best fungicide management options for your area.
To use Sporecaster in other locations, add new fields to your Field List. You can edit the Field List by swiping to delete fields. After you have used Sporecaster on several fields, you can create an email containing the forecast history of multiple fields using the ‘Export’ button.
- If the weather data download is incomplete at the field GPS location (a rare occurrence) and the forecast won’t run, create a new duplicate field a few miles away on the map and re-run the forecast model. The app uses weather data on an ~2 mile grid, so a new location will try to download a similar but new data set.