West Bengal’s Sanjoy Guha Roy Identifies Why Potato Crops Fail Every Year. In India, the potato is more than just a vegetable—it is a staple, a livelihood, and a cornerstone of food security—a silent enemy has long eluded the grasp of science. For decades, farmers in the Indo-Gangetic plains have watched in despair as their lush green fields turned into a blackened, rotting mass within days. This devastation is caused by Late Blight, a disease triggered by the notorious oomycete Phytophthora infestans. While the symptoms were well-known, the source of the recurring infection remained a subject of intense debate. A groundbreaking study led by Professor Sanjoy Guha Roy from the Department of Botany at West Bengal State University (Barasat) has finally unmasked the culprit. Published in the prestigious journal Phytopathology—the century-old flagship publication of the American Phytopathological Society—the research identifies seed potatoes as the primary reservoir for the disease. Specifically, the study reveals that even “high-tech” seed potatoes, produced under laboratory conditions, harbor hidden, dormant infections that bridge the gap between cropping seasons. The Historical Ghost and Modern Economic Toll To understand the weight of this discovery, one must look back at the 1840s. Phytophthora infestans was the primary cause of the Great Irish Potato Famine, which led to the death of over a million people and changed the course of history through mass migration. In modern India, the second-largest potato producer in the world, the pathogen remains a formidable foe. Link According to the research team, Late Blight claims approximately 15% of India’s total potato production annually. In monetary terms, this translates to a staggering loss of roughly ₹2,700 crore. In years where the disease takes an epidemic form, the losses can be even more catastrophic, pushing debt-ridden farmers to the brink of suicide. Despite the use of expensive fungicides, the disease frequently returns, leading scientists to ask: where does the pathogen hide during the blistering Indian summer when the soil temperature becomes too high for it to survive? The Myth of Soil-Borne Survival In many parts of the world, Late Blight survives in the soil through thick-walled structures called oospores. However, in the tropical and sub-tropical plains of India, the intense heat of the “off-season” (summer) was long thought to be lethal to the pathogen. Some experts theorized that the infection migrated every year from the cooler Himalayan regions or survived in alternative host plants. Professor Guha Roy’s research has effectively debunked these theories for the Indian plains. Through rigorous soil testing and experimental trials under high-temperature conditions, the team found no evidence of the pathogen surviving in the soil between seasons. Instead, they turned their attention to the seed tubers themselves. The study involved testing over 7,000 seed potatoes that appeared perfectly healthy to the naked eye. Using advanced molecular diagnostics and genetic analysis, the researchers discovered that approximately 1.6% of these “healthy” seeds were actually asymptomatic carriers. These tubers contained the pathogen in a dormant state, waiting for the cooler, humid conditions of the winter planting season to reactivate and spread to the rest of the crop. The Paradox of High-Tech Seed Production One of the most alarming findings of the study is that even modern seed production systems are not immune. Today, many farmers rely on seeds produced via tissue culture in specialized labs. These “Pre-Basic” seeds are initially pathogen-free. However, before they reach the farmer, they must be “multiplied” in the field or in greenhouses (often called net-houses or glasshouses) to produce enough volume for commercial sale. Link The researchers identified this multiplication phase as the critical point of failure. In many potato-growing regions, such as Punjab and West Bengal, these seed-multiplication nurseries are located in close proximity to commercial potato fields. During the growing season, spores from infected commercial crops can easily find their way into the supposedly “protected” greenhouses through wind or human activity. Once the seed plants are infected, the pathogen hitches a ride inside the newly formed tubers, where it remains hidden throughout the summer storage period. The European Connection: A More Aggressive Lineage The research also provided a genetic profile of the enemy. The dominant strain currently wreaking havoc in India belongs to the “European clonal lineage,” specifically the genotype known as EU_13_A2. This lineage is significantly more aggressive than the strains previously found in India. It is also notably resistant to Metalaxyl, one of the most commonly used and affordable fungicides. The presence of this lineage explains why recent outbreaks have been so swift and difficult to control. By surviving inside the seed potato, this aggressive strain ensures its survival across seasons, effectively “seeding” the next epidemic even before the farmer has finished planting. Identifying the “Stem Lesion” Clue The study sheds light on how the disease begins its visible assault. In many cases, the infection starts not on the leaves, but as small, dark lesions on the stem of the plant. These stem lesions often go unnoticed by farmers in the early stages. However, they serve as a factory for spores that quickly wash down into the soil or blow across the field, leading to the rapid-fire destruction characteristic of Late Blight. The identification of stem-focused infection pathways is crucial for improving early warning systems. If farmers can be trained to look for these early indicators on the stems of emerging plants, they may be able to take preventative action before the entire field is compromised. A Roadmap for the Future The recognition of Professor Guha Roy’s work as an “Editor’s Pick” in Phytopathology highlights its global significance. It provides a clear directive for policymakers and agricultural scientists in India and other developing nations. To break the cycle of Late Blight, the following steps are essential: Stricter Certification and Monitoring: Current seed certification processes must include molecular testing for asymptomatic infections. Relying on visual inspection alone is clearly insufficient. Strategic Relocation of Nurseries: Seed multiplication should be moved to “blight-free” zones or areas geographically isolated from commercial potato crops to prevent cross-contamination. Modern Diagnostic Kits: There is an urgent need to develop affordable, field-level diagnostic kits that can help seed producers and government agencies identify latent infections in stored tubers. Integrated Management: Since the pathogen is now known to be seed-borne, farmers should be encouraged to use certified, tested seeds and adopt “prophylactic” (preventative) fungicide applications rather than waiting for symptoms to appear. Conclusion The work of the West Bengal State University research team marks a turning point in the fight against one of the world’s most devastating plant diseases. By identifying the humble seed potato as the secret hideout for Phytophthora infestans, they have provided the missing link in the epidemiological chain. As India strives to ensure food security for its growing population, protecting the potato crop is non-negotiable. This discovery not only honors the scientific excellence emerging from Bengal but also offers a beacon of hope for millions of farmers whose livelihoods depend on the health of their tubers. The “Silent Saboteur” has been found; the next challenge lies in making sure it has nowhere left to hide.
पश्चिम बंगाल के संजय गुहा रॉय ने पहचान की है कि हर साल आलू की फसलें क्यों असफल होती हैं। भारत में, आलू केवल एक सब्जी नहीं है—यह एक मुख्य खाद्य पदार्थ, जीवन यापन का साधन और खाद्य सुरक्षा का आधार है—एक मौन दुश्मन लंबे समय से विज्ञान की पकड़ से बाहर रहा है। दशकों से, इंडो-गंगेय मैदानों में किसान निराशा से देखते आ रहे हैं जब उनकी हरी-भरी फसलें कुछ ही दिनों में काले, सड़ते ढेर में बदल जाती हैं। यह विनाश लेट ब्लाइट द्वारा होता है, जो कुख्यात ओमीसाइट फाइटोफ्थोरा इंफेस्टन्स द्वारा उत्प्रेरित बीमारी है। जबकि लक्षण अच्छे से ज्ञात थे, पुनरावर्ती संक्रमण का स्रोत गहन बहस का विषय बना रहा। पश्चिम बंगाल राज्य विश्वविद्यालय (बराकपुर) के वनस्पति विज्ञान विभाग के प्रोफेसर संजय गुहा रॉय द्वारा किए गए एक क्रांतिकारी अध्ययन ने अंततः दोषी को बेनकाब कर दिया है। प्रतिष्ठित जर्नल फाइटोपैथोलॉजी में प्रकाशित—अमेरिकन फाइटोपैथोलॉजिकल सोसाइटी का शताब्दी पुराना प्रमुख प्रकाशन—यह शोध बीमारियों के प्राथमिक भंडार के रूप में आलू के बीजों की पहचान करता है। विशेष रूप से, अध्ययन में यह खुलासा किया गया है कि यहां तक कि “उच्...