Cassava brown leaf spot

The disease is caused by the virus Ipomovirus brunusmanihotis, a member of the Potyviridae family. This pathogen specifically targets the vascular tissue of the host plant, disrupting nutrient transport and overall physiological health. Transmission occurs primarily through insect vectors, specifically whiteflies, which acquire the virus while feeding on infected sap and transmit it to healthy tissue.

The primary host for this virus is cassava (Manihot esculenta). Given its global importance as a staple crop in tropical regions, an outbreak of this viral disease can cause severe economic losses and food insecurity. The infection affects all stages of plant growth, often leading to reduced root tuber yields and lower-quality starch production.

Symptoms of the infection typically begin as brown necrotic spots or chlorotic mottling on the leaves. As the virus progresses, leaves may show signs of yellowing, severe curling, or distortion. Infected plants exhibit significantly stunted growth and an overall weakened appearance, making them susceptible to secondary infections or environmental stress.

The development of the disease is heavily dependent on the presence and activity of whitefly populations. Warmer climates with stable humidity levels create ideal conditions for the rapid multiplication of these vectors, leading to fast spread across plantations. The virus can persist in various alternative hosts and contaminated field debris, facilitating annual recurrence.

• Planting certified virus-free cassava cuttings or tissue-cultured plantlets.
• Implementing rigorous whitefly population management and monitoring.
• Rogueing or removing and burning infected plants to limit the inoculum source.
• Maintaining field hygiene by removing alternative weed hosts.
• Rotating crops and selecting cultivars known for higher viral resistance.