Pink root
Phoma terrestris
What is Pink root (Phoma terrestris)?
Pink root (Phoma terrestris) is a devastating fungal disease that primarily affects onion production. It is distributed worldwide and can be found in soil up to 45 cm deep. Besides onions, it can occasionally infect cereals, corn, cucurbits, pepper, spinach, or soybean. The disease is favored by environmental factors such as temperatures between 75-85ºF and heavy, poorly drained soils. The leaves of infected plants may wither, dry up, pink-colored roots turning dark red or purple, root death, and reduced bulb size.
How does Pink root (Phoma terrestris) occurs?
Pink root (Phoma terrestris) reproduces and spreads through fungal spores. The fungus can survive in the soil and plant debris, allowing it to persist and infect subsequent crops. It directly penetrates the roots of susceptible plants, without the need for wounds. The spores are produced in infected plant tissues and can be dispersed by wind, water, contaminated equipment, or through the movement of soil. These spores can then infect healthy plants, leading to the development of pink root disease.
Symptoms
1 - Plants Heath
Pink root disease in onions causes stunted growth, leaf dieback, discoloration of roots, root death, and diminished bulb size. It can lead to reduced yields and negatively impact the overall health and productivity of affected plants. Additionally, fungus, weakens, and compromises the root system.
2 - Soil Health
• The fungus can survive in the soil for extended periods, posing a long-term threat to subsequent crops. • Infestations of Pink root can contribute to soil degradation, especially in fields with repeated onion cultivation. • Infected soil can serve as a source of infection, spreading the disease to other susceptible plants
Solutions
1 - Prevention Strategies
• Avoid planting susceptible crops repeatedly in the same soil. Rotating with different crops helps break the disease cycle and reduces the buildup of pathogens in the soil. • Choose varieties that are resistant to pink root. Resistant varieties have built-in defence mechanisms that make them less susceptible to disease. • Maintain optimal soil fertility and drainage. Healthy soil promotes vigorous plant growth and reduces the risk of infection. Regularly test the soil and amend it with organic matter or fertilizers as needed. • Implement effective pest and disease management practices. Control insect pests and other diseases that can weaken plants and make them more susceptible to pink root. • Prevent the fungus spread by ensuring that equipment used in the field, such as tools and machinery, is properly cleaned and disinfected.
2 - Chemical Treatment
Fungicides that are commonly used for fungal disease control: • Mancozeb: Brand names include Dithane, Manzate, and Penncozeb. • Thiophanate-methyl: Brand names include Topsin and T-Methyl. • Azoxystrobin: Brand names include Amistar and Quadris. • Propiconazole: Brand names include Tilt, Orbit, and Bumper. • Boscalid: Brand names include Endura and Pristine. Specific brand names may vary by region and country, so it is important to consult product labels and local agricultural authorities for proper usage guidelines and availability.
