Sooty stripe of sorghum

These stripes eventually turn reddish-brown or dark brown, reflecting the necrosis of the infected leaf tissue caused by the pathogen.

A distinctive feature of the disease is the development of a dark, sooty-looking mass of spores on the surface of the lesions under humid conditions.

As the infection spreads, the leaves may wither prematurely, significantly reducing the plant's overall photosynthetic capability.

The severity of symptoms often varies depending on the sorghum hybrid, with older leaves showing signs of infection first before spreading upward.

The disease is caused by the fungus Ramulispora sorghi, an imperfect fungus that targets various sorghum species throughout the growing season.

The pathogen survives primarily in crop residues within the soil, forming sclerotia and mycelium that act as the primary inoculum for future seasons.

During the vegetative period, the fungus produces conidia, which are efficiently dispersed by wind currents and water splashes during rainfall.

Once the conidia land on a host plant, they penetrate the leaf tissue and colonize the internal space, disrupting normal plant physiology.

Understanding the life cycle of Ramulispora sorghi is critical for timing control measures and predicting potential disease outbreaks in fields.

High humidity and moderate temperatures ranging from 20 to 25 degrees Celsius are the primary drivers of sooty stripe development.

Frequent rainfall episodes facilitate the rapid spread of spores throughout the crop canopy, increasing the rate of secondary infections.

Dense crop stands create a restricted microclimate with poor airflow, which often retains moisture and promotes fungal colonization.

Field conditions that favor prolonged leaf wetness, such as early morning fog or heavy dew, significantly enhance the progression of the disease.

Inconsistent crop rotation and the presence of infected stubble from previous years remain the most significant factors for disease outbreaks.

The primary economic impact of sooty stripe is the reduction of leaf area, leading to lower rates of biomass production and grain filling.

Severe infections can cause significant grain yield losses, often ranging from 10% to 20% in susceptible varieties under favorable conditions.

The nutritional quality of the plant is compromised, which is particularly detrimental if the sorghum is being grown for silage or livestock feed.

Plants weakened by the pathogen become more susceptible to lodging and secondary pests, further complicating harvest management.

The decline in overall plant health during critical growth stages can lead to uneven maturity and poor seed quality for future planting.

Implementing a robust crop rotation program is the most fundamental practice to disrupt the life cycle of the pathogen and reduce field inoculum.

Effective management of crop residues, such as deep tillage or destruction of stubble, helps minimize the sources of primary infection.

Selecting and planting genetically resistant or tolerant sorghum hybrids is the most sustainable and efficient long-term solution for management.

Optimizing plant population and row spacing improves field ventilation, which helps to lower canopy humidity and slow down disease spread.

In areas with high disease pressure, the application of appropriate systemic fungicides can effectively protect the crop during the most vulnerable growth stages.