Asian soybean rust is the fastest-moving foliar disease in modern row-crop agriculture, and the reason strict fungicide-group rotation exists as a legal requirement in several producing countries.
- Grown in
- Brazil, USA, Argentina, India, Nigeria, China
- Season
- 90–120 days
- Soil & pH
- Well-drained loam, pH 6.0–7.0
What to scout for on Soybean
- Tan pustules on leaf undersides that rupture — soybean rust
- Interveinal chlorosis from iron or manganese limitation
- Purple seed staining at harvest
- Wilting patches spreading along the row — Fusarium or Sclerotinia
Diseases that attack Soybean
Leaf Spot
Septoria, Cercospora, Alternaria spp.
Rust Disease
Puccinia, Uromyces spp.
Nitrogen Deficiency
Abiotic — nutrient stress
Products you can buy for Soybean
Typical registered products for the diseases above, with active ingredient, mixing rate, spray interval and pre-harvest interval. Rotate FRAC/IRAC groups to avoid resistance.
Tebuconazole 25% EC
Active ingredient: Tebuconazole
- Dose:
- 1 ml per litre (500 ml–1 L/ha)
- Interval:
- Every 14–21 days, 2 sprays per season
- PHI:
- 21–35 days on cereals
The standard cereal-rust curative. Apply at first pustule, and again at flag-leaf if pressure continues.
Propiconazole 25% EC
Active ingredient: Propiconazole
- Dose:
- 1 ml per litre
- Interval:
- Every 14–21 days
- PHI:
- 21–30 days
Widely used on coffee leaf rust and cereal rusts; rotate with a strobilurin.
Azoxystrobin + cyproconazole
Active ingredient: Azoxystrobin 20% + Cyproconazole 8%
- Dose:
- 1 ml per litre
- Interval:
- Every 21 days, 1–2 per season
- PHI:
- 30 days
Built-in two-mode mixture — the safest way to slow rust resistance in intensive systems.
Copper oxychloride 50% WP
Active ingredient: Copper oxychloride
- Dose:
- 3 g per litre
- Interval:
- Every 14 days through the rainy season
- PHI:
- 3–5 days
Standard preventive base for coffee leaf rust in smallholder systems.
Chlorothalonil 75% WP
Active ingredient: Chlorothalonil
- Dose:
- 2 g per litre (1.5–2 kg/ha)
- Interval:
- Every 7–10 days
- PHI:
- 7 days
Backbone protectant for Septoria and Cercospora leaf spots. Full leaf coverage, including undersides, is essential.
Mancozeb 80% WP
Active ingredient: Mancozeb
- Dose:
- 2.5 g per litre
- Interval:
- Every 7 days
- PHI:
- 7 days
Adds zinc and manganese nutrition alongside disease control.
Doses shown are typical registered field rates. Always read the product label, confirm the product is registered for your crop and country, respect the pre-harvest interval (PHI), and wear the protective equipment the label specifies. PlantWatch AI provides agronomic guidance, not a legal spray recommendation.
Is your Soybean showing symptoms right now?
Photograph the leaf and PlantWatch AI will diagnose the disorder and prescribe the exact product, dose and spray interval to use next.
Diagnose a plant