Maize chlorotic mottle

Pathogen and disease type. Maize chlorotic mottle virus (MCMV) is a significant plant pathogen belonging to the Machlomovirus genus. It is a viral disease that can occur independently, but it is most notoriously known for forming complex infections with other viruses, such as the Maize dwarf mosaic virus, which results in the lethal maize necrosis disease.

Host range. The primary host for this pathogen is maize (Zea mays). While it shows a high affinity for cultivated corn, the virus can also persist in various wild grass species which serve as secondary reservoirs, allowing the infection to survive in the field during the off-season.

Symptoms and signs of infection. Infected plants exhibit characteristic chlorotic mottle or spots on the leaves, which often develop into severe mosaic patterns. As the disease progresses, leaves may show significant necrosis, plant stunting is common, and the development of ears is severely impaired. In many cases, the ears remain small, deformed, and produce little or no viable grain.

Development and spread. The virus is transmitted by insect vectors, including various species of corn rootworms, beetles, and thrips. Spread is highly dependent on the population density of these vectors and environmental factors like temperature, which favor insect activity. Furthermore, the virus is easily transmitted mechanically, making the movement of farm machinery between infected and healthy fields a primary concern.

Damage and control measures. This disease poses a severe threat to food security, potentially leading to total crop failure in susceptible fields. Management strategies are focused on the integration of multiple approaches:

• Selection of resistant or tolerant maize hybrids.
• Rigorous insect vector monitoring and control via insecticide application.
• Sanitation practices, including the removal of infected plant debris.
• Implementation of crop rotation and timely weed management to remove alternative hosts.