Boost Your Bushels | Syngenta US

Showing Results for

Back to Disease Search

The Problem

Jump to the Solution

Brown Spot

  • Cause: Septoria glycines
  • Environment: Requires moisture to grow and prefers warm, humid conditions
  • Timing: Can develop as early in the season as when the first true leaves develop
  • Appearance: Light to dark brown lesions that start on the lower leaves of plants, becoming more irregular in shape as they expand. Chlorosis or yellowing can occur around the lesions
  • Risk: Damage to leaf tissues and decreased yield potential
Photo of Septoria brown spot damage in soybean leaves

Close up of a soybean leaf with brown spot infection

Close up image of soybean leaves infected with Septoria brown spot

Septoria brown spot infection in the lower soybean canopy

Brown spot infected soybean leaves showing yellowing beginning on lower leaves.

Starts on lower leaves as small brown lesions.

Expand to Learn More

Understanding Brown Spot in Soybeans

Brown spot is caused by the fungus Septoria glycines and is one of the most common foliar diseases found in soybeans, occurring naturally almost everywhere soybeans are grown. Often resulting in defoliation and plant-health problems, brown spot can lead to premature plant death and yield loss. The disease can manifest in three key ways:

Lower-leaf lesions

Brown spot symptoms appear soon after emergence and can cause small angular to circular lesions varying in size.

Yellowing and defoliation

Lesions grow in size, causing leaves to yellow and drop. Infected leaves may develop yellowing around lesions and fall off prematurely.

Progression based on weather

If weather conditions say humid for long periods of time, the disease can progress into the upper canopy during grain fill.

Why Brown Spot Matters

Brown spot is found in most U.S. soybean-growing states and is highly dependent on weather and canopy position. While it is often confused with other foliar diseases, it plays a key role in fungicide timing decisions and disease scouting conversations.

 

Since brown spot develops early and thrives in warm, humid conditions, it is commonly found throughout the Soybean Belt in states like Iowa, Illinois and Indiana, where dense canopies and frequent moisture allow it to build quickly.

Why Brown Spot Matters

The Solution

Use Miravis Neo to Fight Brown Spot

  • Active Ingredients: ADEPIDYN® technology, Azoxystrobin, Propiconazole
  • Why Miravis Neo Works: Delivers dual-yield protection with broad‑spectrum disease control with a long‑lasting residual and added plant‑health benefits.
  • Crops: Corn and Soybeans
  • Benefits: Delivers consistent, comprehensive control and is the only premium fungicide labeled for Fusarium / Gibberella ear rots.

Why Use a Cleaner & Greener Fungicide?

From disease to crop stress, you don't know what the season will bring so your yield potential needs protection on all fronts! That's why only Cleaner & Greener fungicides are powered by exclusive ADEPIDYN® and SOLATENOL® technologies to provide a step change in broad-spectrum disease control and protection from crop stress like drought.

Cleaner & Greener