Yellow dwarf of sorghum

Yellow dwarf of sorghum is a viral disease caused by the Sorghum yellow dwarf virus, which significantly impairs the physiological processes of host plants. As a systemic pathogen, it primarily colonizes the phloem tissues, disrupting the transport of nutrients and sugars throughout the plant organism.

The disease affects various sorghum cultivars, leading to characteristic symptoms such as chlorosis (yellowing of foliage), stunting of internodes, and significant reductions in biomass and grain yield. Infected plants often show stunted growth compared to healthy neighboring crops, which is the most prominent diagnostic indicator in the field.

The biology of the pathogen relies on insect vectors, specifically aphid species. The virus is acquired by the insect while feeding on the phloem of an infected plant. Once the virus enters the aphid's circulatory system, it remains transmissible for the duration of the insect's life, facilitating the rapid spread of the disease across fields.

The epidemiology of yellow dwarf is highly dependent on environmental conditions that favor aphid population dynamics. Mild temperatures and favorable humidity accelerate the multiplication and movement of vectors. Furthermore, the presence of perennial weed hosts around field margins acts as a critical reservoir for the virus between growing seasons.

Economic damage manifests as poor grain filling, reduced head size, and sometimes complete loss of yield in severely infected crops. Control measures focus on managing the vector populations and minimizing disease reservoirs:

• implementing early warning systems for aphid migration;
• applying systemic insecticides to manage vector populations;
• eliminating grass weeds that harbor the virus;
• selecting and planting resistant or tolerant hybrid varieties.