Frog eye leaf spot is a common fungal disease in soybean that can spread quickly in warm, humid weather, causing early leaf fall and yield loss if left unmanaged. It's caused by the fungus Cercospora sojina.
Signs of Frog Eye Leaf Spot in Soybean
- Small circular spots on the leaves with a grey-brown centre and a reddish-brown border
- Spots often merge as the disease progresses, giving leaves a speckled, scorched look
- Lesions can also appear on stems, pods, and seeds in severe cases
- Heavily infected leaves turn yellow and drop early
- Seeds from infected pods may show a pale, discoloured patch
Causes of Frog Eye Leaf Spot in Soybean
- Warm temperatures combined with high humidity or frequent rain
- Continuous soybean cultivation in the same field without rotation
- Infected crop debris left on the soil surface from a previous season
- Use of infected or uncertified seed
- Dense canopy that keeps humidity high and slows leaf drying
Prevention of Frog Eye Leaf Spot in Soybean
- Use certified, disease-free seed
- Rotate soybean with a non-host crop where the disease has occurred before
- Clear and destroy infected crop debris after harvest instead of leaving it in the field
- Maintain proper plant spacing to improve airflow and reduce humidity in the canopy
- Monitor the crop closely from the flowering stage onward, when the disease tends to spread fastest
Solutions to Treat Frog Eye Leaf Spot in Soybean
1. Fluxapyroxad 167 g/l + Pyraclostrobin 333 g/l SC
This combination pairs an SDHI fungicide with a strobilurin, giving soybean dual-action, long-lasting control of frog eye leaf spot. It also improves the plant's tolerance to stress, keeping leaves greener and healthier through the season.
Product Recommendation
2. Pyraclostrobin 20% WG
Pyraclostrobin is a strobilurin fungicide that blocks energy production inside fungal cells, stopping the disease from spreading further. Its granular formulation dissolves easily and gives even coverage across the leaf canopy.
Product Recommendation
Note: Both these products belong to related fungicide groups, so where possible, rotate with a fungicide from a different mode of action across the season to avoid resistance development.
Disclaimer: Always confirm current label registration, approved dosage, water volume, and pre-harvest interval (PHI) for your state before using any product, since labels are periodically revised by regulatory authorities.
This guide is a general advisory. Do your own research and verification before using any product. Always confirm suitability for your crop stage, region, and field conditions before making any purchase, spray, or crop-management decision.
