Phoma blight of chickpea

Symptoms of Phoma blight include the appearance of localized lesions that are typically light brown with a darker margin on leaves and stems.

A hallmark of the disease is the presence of dark, pin-point structures (pycnidia) arranged within the necrotic lesions on affected plant parts.

Infection often starts at the base of the plant, causing stem girdling, which can lead to wilting and the subsequent death of the young chickpea plants.

On pods, the disease manifests as small, sunken, irregular spots that can prevent proper seed development and reduce overall yield quality.

As the infection progresses, large sections of the canopy may appear blighted, with yellowing and premature leaf senescence observed across the affected areas.

The causative agent of Phoma blight of chickpea is the fungus Boeremia noackiana, an Ascomycete fungus that causes severe damage to legume crops.

The pathogen is known for its ability to persist in soil and crop debris, utilizing these as primary inoculum sources for the following growing season.

The fungus produces pycnidia, which serve as specialized structures for the survival of the pathogen under diverse environmental conditions.

Conidia are released from pycnidia and dispersed by wind-driven rain or irrigation, facilitating the rapid spread of the disease within the field.

The fungal mycelium colonizes plant tissues systemically or locally, depending on the severity of the initial infection and environmental pressure.

The development of Phoma blight is strongly favored by cool to moderate temperatures and high relative humidity during the vegetative growth stages.

Persistent rainfall during the flowering period provides the necessary moisture for spores to germinate and penetrate the plant epidermis successfully.

Poor field drainage and excessive irrigation contribute to favorable microclimatic conditions that accelerate the proliferation of the fungal pathogen.

High plant density increases humidity levels within the canopy, creating a conducive environment for the rapid secondary spread of the disease.

Soils that have hosted previous legume crops without adequate rotation allow for higher inoculum loads, increasing the risk of early-season outbreaks.

Phoma blight causes significant economic losses by reducing both seed quantity and seed quality in infected chickpea crops.

Infected seeds can harbor the pathogen, which serves as a significant risk factor for yield reduction in subsequent production cycles.

The disease impairs the photosynthetic efficiency of the crop, resulting in shriveled seeds and reduced grain weight at the time of harvest.

Stem infections weaken the structural integrity of the plant, leading to lodging and difficulty in mechanical harvesting operations.

The blighted crop is more susceptible to environmental stressors, further compromising the potential yield and overall financial viability of the farm.

The primary control strategy involves using high-quality, disease-free seed that has been tested for fungal pathogens before planting.

Implementing a diversified crop rotation plan, including non-host crops, is essential to decrease the concentration of Boeremia noackiana in the soil.

Sanitation practices, including the deep burial or removal of crop residues, help to eliminate the primary sources of inoculum in the field.

Fungicidal seed treatments provide early-season protection, significantly reducing the incidence of seedling damping-off and systemic infection.

Foliar application of systemic fungicides at the onset of symptoms or during high-risk periods is recommended to manage the spread of the disease effectively.