Soybean White Mold Map Description

The soybean white mold risk prediction maps give the risk probability for the development of white mold mushrooms, called apothecia. These apothecia are the source of inoculum for disease development. These apothecia will only develop under specific environmental conditions such as cool soil temperatures (50-70F), soil moisture, and canopy closure. White mold infections will only occur when soybean flowers are present (R1-R3 growth stages).

These maps are meant to guide recommendations on when to apply fungicide products for the management of white mold in soybeans. These risk models have not been validated in any other crop other than soybeans, so caution is advised when considering other crops such as canola, dry beans, and sunflowers. It is important to only use this tool when flowers are present on the soybeans and after canopy closure has occurred. If either of these conditions is not present, then the risk of disease development is drastically reduced.

When the map is blue, this means the risk level is Low for your area. When the map is yellow, this means the risk level is Moderate for your area. When the map is red, this means the risk level is High and a fungicide application is recommended. Previous studies have shown that white mold susceptible varieties may benefit from fungicide applications within the Moderate risk level.

These models have been shown to have an accuracy of 78% in North Dakota, but there are still instances in which the models are inaccurate in specific microenvironments.

This work was supported in part by the North Dakota Soybean Council for validation of models in North Dakota.