Alternaria Leaf Spot

Alternaria leaf spot is an infectious fungal ailment instigated by Alternaria spp. It negatively impacts various plant species, resulting in considerable damage. The growth of this disease thrives in warm and damp climatic conditions, while adequate moisture is crucial for the spores to germinate effectively.

Plants that are younger, older, or lacking essential nutrients are more prone to being targeted by this ailment.

Host Range

Alternaria leaf spot affects a diverse array of plants, encompassing tomato, cabbage, crucifers, beans, potato, pepper, cucumber, ornamentals, and various others.

Life Cycle

The fungus is classified as a saprobe, meaning it sustains itself by feeding on deceased plant matter. It generates spores that can be disseminated to healthy plants through wind or rain, leading to the initiation of infections.

The spores of Alternaria leaf spot have the ability to survive throughout the winter on aging plant remnants and can also cling to seeds. This characteristic makes it challenging to completely eradicate the disease, particularly when replanting seeds.

Infection & Symptoms

The occurrence of infection results in the formation of lesions on the leaf surface, characterized by small, dark circular spots featuring light brown centers encircled by concentric rings of a darker shade. This spotting primarily manifests on lower and older leaves, although new leaves can also be susceptible to attack. The centers of these lesions may eventually disintegrate, causing the leaf spots to resemble small holes, similar to a shot-hole appearance.

The absence of water causes leaves to develop numerous spots, leading to their yellowing, wilting, and eventual falling.

While leaves are primarily susceptible to these symptoms, other plant parts such as stems, flowers, and seed pods can also experience their effects.

Management & Control

Given the significant losses caused by infections of Alternaria leaf spot, it is crucial to prioritize timely and effective disease control and management. This objective can be accomplished through various approaches, including:

Chemical Method

One method involves employing fungicides, which have both preventive and curative properties, making them effective against Alternaria leaf spot. The following fungicides have been found to be particularly effective:

    • ABSOLUTE 375SC 10ml/20l
    • BRADLEY 500SC 10ml/20l
    • CHARIOT 500SC 20ml/20l
    • COLONIZER 440WP 50g/20l
    • DOMAIN 250EC 10ml/20l
    • DUCASSE 250EW 20ml/20l
    • EXEMPO CURVE 250SC 15ml/20l
    • IPRODE 500SC 10ml/20l
    • JUPITER 125SC 15ml/20l
    • MEGAPRODE LOCK 525WP 20g/20l
    • MILLIONAIRE 690WDG 40g/20l
    • MONUMENT 400EC 40ml/20l
    • PROVIDENCE 400WP 50g/20l
    • PYRAMID 700WP 50g/20l
    • RIMETA GOLD 300SC 40ml/20l
    • TOWER 720WP 50g/20l
    • TRINITY GOLD 425WP 50g/20l

Note;

    • To enhance the efficacy of any fungicide during spraying, it is advisable to mix it with INTEGRA at a ratio of 3ml per 20 liters.
    • The punctual application of the fungicide is of utmost importance.
    • By alternating the use of different fungicides throughout a crop season, the pathogen is prevented from developing resistance to any particular fungicide.

Other methods

To prevent and manage the disease effectively, several strategies can be employed, including:

    • Utilizing resistant varieties of plants.
    • Planting certified or disease-free materials.
    • Implementing crop rotation with non-host plants.
    • Maintaining field hygiene practices.
    • Ensuring proper weed control measures are in place.

These approaches contribute to effective disease management and prevention.

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