Soybean Diagnostic Guide

Troubleshooting Techniques and Diagnostic Aids

1. Identify the soybean growth stage when the problem occurs and know the types of problems and their symptoms which can occur at this stage.

2. When examining affected plants, try to determine if the problem occurred at one time or if it is continuous. All affected plant parts should be identified and symptoms noted.

3. Compare symptoms with those described in this troubleshooting guide.

4. When satisfactory diagnostic decisions cannot be made, take soil samples for nematode and fertility status and plant tissue samples for further fertility and pest diagnosis. All samples should be paired, i.e. one for normal soybeans and one from affected soybeans.

**Field identification.
**Cropping history (for at least the previous two growing seasons).
**Soil test results (soil pH and levels for P, K, Ca, and Mg).
**Plant tissue test results (major plus most secondary and minor nutrients).
**Soil nematode assay results (species and population levels, including races, if possible, eg. Soybean cyst).
**Fertilizer and liming practices (time, rate, and method of application).
**Pesticide application (time, rate and method of application).
**Tillage and planting procedures.
**Other cultural management information (eg. rainfall, soybean variety, soil temperatures, etc.)

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