Stem-end browning

Stem-end browning is a physiological disorder of potato tubers characterized by internal necrosis of the vascular tissue, originating at the stolon end. Unlike parasitic diseases, this condition is non-infectious and arises from the plant's stress response to unfavorable environmental conditions during the tuber development stage.

The primary crop affected by this disorder is the potato. Tubers often appear normal from the exterior, but when sliced across the stolon end, dark brown to black necrotic streaks or a ring are visible. The severity of the browning can range from slight discoloration to deep, extensive necrosis within the vascular ring.

The development of stem-end browning is triggered by high-stress environmental factors. Key contributors include extreme fluctuations in soil temperature, prolonged drought followed by heavy irrigation or rainfall, and nutrient imbalances, particularly high nitrogen application levels which can disrupt the proper translocation of nutrients and water to the tubers.

The economic impact of this disorder is significant for both fresh markets and the processing industry. Affected tubers are downgraded or rejected because the necrotic areas darken significantly during frying or baking, leading to unacceptable consumer quality. Furthermore, the weakened tissues can become susceptible to opportunistic secondary infections during long-term storage.

Management and prevention focus on maintaining consistent soil conditions throughout the growing season. Strategies include:

• implementing efficient irrigation scheduling to prevent moisture stress;
• using straw mulch or irrigation to moderate soil temperature;
• balancing fertilizer applications according to soil test results;
• selecting potato varieties that demonstrate high tolerance to heat and drought stress.