Cotton is a widely cultivated crop valued for its fiber and seeds. One of the significant challenges faced by cotton farmers is Fusarium Wilt, a disease caused by the fungus Fusarium oxysporum f. sp. vasinfectum. This disease can result in significant financial losses and is persistent in the soil through chlamydospores and its association with the roots of various plants, including Cotton, non-cotton hosts, and resistant plants, as well as through contaminated seeds. The cotton plant, Gossypium hirsutum, is prone to infections from bacteria, viruses, and fungi. All plant sections are affected, and crop losses are frequent.
Fusarium Wilt management in Cotton
The causal organism of Fusarium Wilt disease
The fungal pathogen Fusarium oxysporum causes Fusarium wilt disease of Cotton, which affects a wide variety of plants, including tomatoes, tobacco, legumes, cucurbits, sweet potatoes, and bananas. Wilting, yellowing, stunting, leaf drop, browning of the vascular system, and plant death are all indications of the illness. The most noticeable symptom is vascular wilt, which begins with vein clearing on young leaves, progresses to drooping of older leaves, and eventually leads to plant death. The disease symptoms are more severe in older plants during the flowering and fruit maturity periods.
Disease cycle of Fusarium Wilt disease
A widespread and prevalent soil fungus called Fusarium oxysporum causes Fusarium wilt disease in plants like Cotton. Microconidia, macroconidia, and chlamydospores are the three kinds of spores produced by this asexual pathogen. Chlamydospores are the most durable fragment and may last a long time in the soil. The infection is disseminated through contaminated planting tools, water splashes, infected seeds, and transplants. It enters plants by wounds, lateral roots, or root tips. Mycelium enters the plant and moves into the xylem, clogging the vascular veins and causing the plant to stop transferring nutrients, wilt, and eventually die. After then, the fungus keeps multiplying and infects nearby plants.
Favorable conditions for the spread of Fusarium Wilt disease
Fusarium oxysporum is a prevalent soil saprophyte that infects many plant species worldwide and can live in arctic, tropical, and desert soil conditions. High temperatures and warm wet soils promote disease development, with ideal growth temperatures for the fungus on an artificial medium ranging from 25-30 °C and 30 °C or above for root infection.
Seed infection, on the other hand, can develop at relatively low temperatures of 14 °C. Light, sandy, acidic soils, nitrate-based fertilizers, and root-knot nematodes can all contribute to the development of Fusarium Wilt. In brief, environmental factors such as soil type and condition, fertilizer use, and plant parasitic nematodes can all contribute to the disease’s prevalence.
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Symptoms of Fusarium Wilt disease in Cotton
- Yellowing and browning of the cotyledons are the first signs of Fusarium wilt disease in cotton seedlings, followed by a brown ring on the petiole, which leads t