Yellow Rust in Wheat
गेहूं में पीला रतुआ — पहचान और नियंत्रण
Introduction / परिचय
Yellow rust (stripe rust), caused by Puccinia striiformis f. sp. tritici, is a major threat to wheat in northern India — Punjab, Haryana, Uttar Pradesh, Uttarakhand, and Himachal Pradesh. Epidemics in 2020–21 wiped out 15–20% of yields in affected districts. Early identification saves the crop.
पीला रतुआ (Puccinia striiformis) उत्तर भारत में गेहूं की प्रमुख बीमारी है। पंजाब, हरियाणा, उत्तर प्रदेश, उत्तराखंड और हिमाचल प्रदेश में 2020–21 में 15–20% उपज हानि हुई थी।
Identification / पहचान
Symptoms / लक्षण
- Bright yellow-orange pustules arranged in distinct stripes running parallel to leaf veins — unlike brown rust which has randomly scattered pustules
- Pustules first appear on upper leaf surface of young leaves and leaf sheaths
- Infected leaves turn yellow, then brown and dry as pustules rupture and release urediospores
- In severe infection, entire flag leaf turns yellow — direct impact on grain filling
- पत्ती की नसों के समानांतर धारियों में चमकीले पीले-नारंगी pustules — भूरे रतुआ से अलग जो बिखरे होते हैं
- pustules पहले युवा पत्तियों की ऊपरी सतह पर दिखते हैं
- गंभीर संक्रमण में फ्लैग लीफ पूरी तरह पीली पड़ जाती है — दाने भरने पर सीधा असर
Differentiation from Brown Rust / भूरे रतुआ से अंतर
| Character | Yellow Rust / पीला रतुआ | Brown Rust / भूरा रतुआ |
|---|---|---|
| Pustule colour | Bright yellow-orange | Reddish-brown |
| Arrangement | Striped (parallel to veins) | Scattered, random |
| Preferred temperature | 7–15°C (cool) | 15–22°C (warmer) |
| Stage affected | Seedling to flag leaf | Mainly heading–grain fill |
Favourable Conditions / अनुकूल परिस्थितियां
- Temperature: 7–15°C with cool nights
- High relative humidity (>80%) and dew on leaves
- Dense crop stands; susceptible varieties
- January–March is peak risk period in north India
Economic Threshold / आर्थिक दहलीज
- Spray immediately when any yellow stripe pustules are visible on flag leaf or the leaf below it
- Do not wait for 5–10% infection — this disease spreads exponentially under cool, humid conditions
Chemical Control / रासायनिक नियंत्रण
| Product | Active Ingredient | Dose/acre | Remarks |
|---|---|---|---|
| Propiconazole 25% EC | Propiconazole (DMI) | 100–120 ml | Standard; low cost; widely available |
| Tebuconazole 25.9% EC | Tebuconazole (DMI) | 150 ml | Good systemic movement |
| Tebuconazole 50% + Trifloxystrobin 25% WG | DMI + Strobilurin | 80–100 g | Broad-spectrum; 2 MoA groups; best for epidemic conditions |
| Azoxystrobin 11% + Tebuconazole 18.3% SC | Strobilurin + DMI | 200 ml | Protective + curative; rainfast |
Spray volume: 200 litres water per acre. Ensure complete upper canopy coverage including flag leaf.
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Spray Timing / छिड़काव समय
- First spray: At first sign of disease (do not wait)
- Second spray: 15 days later if conditions remain cool and humid
- Pre-harvest interval (PHI): Observe label; most products: 21–35 days PHI
Resistant Varieties / प्रतिरोधी किस्में
Use rust-resistant varieties where possible: HD-3086, HD-2967 (with resistance genes), DBW-187, WH-1105. Check local recommendations from ICAR-IIWBR or your state agriculture department.
Prevention Summary / रोकथाम सारांश
- Scout fields weekly from December onwards in north India
- Act immediately — do not wait for high disease incidence
- Rotate DMI and strobilurin groups
- Use certified seed of rust-resistant varieties next season
- Report epidemic situations to the local agriculture officer for area-wide warnings
