Orobanche Threat to Mustard: How a Parasitic Weed Is Undermining India’s Edible Oil Crop

Orobanche Threat to Mustard Latest News

• Mustard is India’s largest indigenous source of edible oil, cultivated across nearly nine million hectares, mainly in Rajasthan, Uttar Pradesh, Madhya Pradesh, Haryana and West Bengal.
• However, the crop is increasingly threatened by Orobanche aegyptiaca, a parasitic weed that attaches to mustard roots and siphons off water and nutrients, leading to poor plant growth and reduced seed yields.

How Orobanche Damages the Crop

• Orobanche attaches itself to mustard roots underground and siphons off water, nutrients and carbon. 
• This leads to wilting, yellowing, stunted plant growth and ultimately sharp declines in seed yields. 
• Because the parasite remains hidden below the soil initially, damage is already extensive by the time it becomes visible.

Farmers See Sharp Yield Losses

• Farmers report steep yield declines despite following recommended control measures. 
• In Haryana’s Sirsa district, yields have fallen from 9–12 quintals per acre earlier to nearly 6 quintals per acre in recent seasons. 
• Even herbicide sprays have shown little effect, pushing farmers to reduce mustard acreage in favour of wheat, chickpea and barley.

Why Infestation Is Spreading Fast

• Each Orobanche plant produces thousands of tiny seeds that can remain viable in soil for up to 20 years and spread through wind and water. 
• Fields repeatedly planted with mustard are especially vulnerable, as irrigation creates ideal conditions for seed germination and rapid underground attachment to crop roots.
• The rising infestation has shaken farmer confidence in mustard, traditionally valued for its low irrigation needs. 
• As Orobanche spreads, many farmers are cutting back on mustard cultivation, raising concerns over future domestic edible oil production.

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Why Mustard Matters for India

• Mustard is India’s most important edible oilseed crop, contributing over 4 million tonnes out of the country’s 10.5–10.6 million tonnes of annual indigenous edible oil production. 
• It is central to efforts to cut India’s heavy dependence on edible oil imports.
• Reducing Import Dependence – India imports nearly 16 million tonnes of edible oils every year — mainly palm, soybean and sunflower oil — costing $15.9 billion in 2023–24 and $18.3 billion in 2024–25. 
  • Improving mustard yields is therefore a key national priority to reduce this import bill.
• Rising Disease and Pest Pressure – Mustard’s increasing vulnerability to Orobanche (margoja), along with pests like aphids and fungal diseases such as white rust, leaf blight, stem rot and powdery mildew, has emerged as a serious concern for productivity and farmer confidence.

Farmers Flag Changing Threat Patterns

• Farmers report that Orobanche infestation is now appearing earlier in the crop cycle and in fertile soils, unlike earlier when it emerged later and mostly in sandy fields. 
• This shift signals a growing and more aggressive threat.
• The buildup of long-lasting Orobanche seed banks in soil has increased the weed’s damage potential, enabling early emergence and greater yield losses. 
• This has left farmers increasingly uncertain, sowing mustard largely on hope rather than confidence.

Herbicides as a Possible Control Tool

• Chemical control using herbicides such as glyphosate is one possible way to tackle Orobanche. 
• However, this approach has major limitations with conventional mustard varieties.

Why Conventional Herbicides Don’t Work

• Glyphosate and similar broad-spectrum, non-selective herbicides kill all plants by blocking the EPSPS (5-enolpyruvylshikimate-3-phosphate synthase) enzyme essential for protein formation. 
• Applied to normal mustard, they destroy the crop along with the weed. 
• At currently recommended low doses, they are also ineffective against Orobanche.

Role of Herbicide-Resistant Mustard

• A new approach lies in breeding mustard varieties that can tolerate specific herbicides. 
• Farmers are testing a hybrid mustard that is resistant to imidazolinone herbicides, allowing selective control of Orobanche without harming the crop.
• The hybrid ‘Pioneer-45S42CL’ can tolerate imazapyr and imazapic herbicides.
• Sold with a compatible herbicide formulation, it requires a single spray after 25 days of sowing and has shown encouraging early results in farmers’ fields.

GM Mustard as a Future Option

• Researchers have also developed GM mustard lines resistant to glyphosate and other herbicides, offering multiple chemical options and reducing the risk of resistance buildup.
• Given mustard’s strategic importance and the rising weed threat, policymakers face a critical decision on permitting GM crops. 
• Any decision, experts argue, should be guided by science and farm economics rather than ideology.

Source: IE