Peronosclerospora

Initial symptoms are characterized by longitudinal chlorotic stripes on the leaves, often starting from the base of the leaf blade.

Under high humidity conditions, a dense, white, downy fungal growth appears on the undersides of the leaves, consisting of masses of conidia.

Infected plants frequently exhibit severe stunting, shortened internodes, and a bushy appearance due to excessive tillering.

Reproductive organs such as tassels and ears often undergo malformation, turning into leafy, sterile tissues that produce no grain.

• Longitudinal chlorotic striping on leaves
• White downy fungal growth on leaf undersides
• Significant stunting and deformation
• Sterility of reproductive structures
• Chlorosis and necrosis of leaf tissues

The disease is caused by obligate biotrophic oomycetes belonging to the genus Peronosclerospora, which specifically target cereal crops.

Common species such as Peronosclerospora sorghi cause systemic infection, leading to stunted growth and severe yield losses in susceptible plants.

The pathogen completes its life cycle by producing asexual conidia on the leaf surface, which are easily disseminated by wind currents.

Oospores act as the primary survival structure in the soil, allowing the fungus to persist even in the absence of a host for several seasons.

Once infection occurs, the pathogen colonizes the internal tissues of the plant, disrupting physiological functions and nutrient transport.

The development of the disease is highly dependent on environmental conditions, specifically high relative humidity and moderate temperatures.

Optimal infection occurs when nightly temperatures range between 20°C and 25°C accompanied by heavy dew or frequent rainfall.

Systemic infection is most likely to occur at the seedling stage when the plants are highly susceptible to penetration by zoospores.

Water-saturated soils or prolonged periods of leaf wetness significantly increase the rate of conidial germination and host penetration.

Warm nights during the early growth season facilitate the rapid expansion of the pathogen within the host plant tissues.

Peronosclerospora is a devastating disease capable of causing total crop failure in susceptible maize or sorghum fields.

Plants affected at an early stage usually fail to produce any viable grain, leading to direct economic losses for farmers.

The disease reduces the vigor and metabolic efficiency of the crop, making it susceptible to secondary environmental stresses.

In regions where the pathogen is endemic, it poses a persistent threat to agricultural productivity and food security.

Management costs are high due to the necessity of combining genetic, cultural, and chemical approaches to suppress outbreaks.

The primary control measure is the deployment of resistant or tolerant hybrid varieties tailored to specific regions.

Crop rotation remains a fundamental practice to reduce the inoculum density of oospores present in the soil environment.

Seed treatments with systemic fungicides are essential to protect the vulnerable seedling stage from initial infection.

Effective sanitation, including the destruction of crop debris, helps to break the survival cycle of the pathogen between seasons.

Adjusting planting dates to avoid environmental conditions favorable for the disease can mitigate the risk of severe infestations.