Wilt disease is one of the most significant constraints on global sugarcane production, resulting in significant yield losses. The disease is caused by a soil-borne fungus that attacks the vascular system of the sugarcane plant, causing wilting, stunting, and eventually mortality. The symptoms include leaf yellowing and drying, stunted growth, and premature plant mortality. Identification of wilt disease is essential for effective management.
Preventative measures such as seed treatment, crop rotation, and soil moisture maintenance can help reduce the disease’s incidence. For the management of sugarcane wilt disease, chemical, biological, natural, and organic control methods are available. Integrated disease management strategies combining multiple control measures are recommended for effective disease control.
Wilt Management in Sugarcane
The Causal Organisms of Wilt Disease
Cephalosporium sacchari, a soil-borne fungus belonging to the Deuteromycetes class, Moniliales order, and Moniliaceae family, causes wilt disease in sugarcane. The pathogen can be identified by observing erect and branched conidiospores and abundant macroconidia that are falcate, 3-5-septate, have a distinct foot cell, and measure 3.4-5.2 mm in size.
The blastoconidia of the pathogen are straight or slightly curved, 2-3-septate, fusiform to lanceolate, with a somewhat pointed, frequently slightly asymmetrical apical cell and a truncated basal cell, and they range in size from 3.0-4.5 mm.
The Disease Cycle of Wilt Disease
The fungus-caused wilt disease is transmitted through infected seedlings and can persist in the soil for two to three years. The fungus generates hyaline, thin-walled, and septate hyphae that produce ovoid to elliptical microconidia. The pathogen is distinct from Fusarium because it lacks macroconidia. Conidia germinate to form germ tubes. The fungus can infect branches, resulting in wilting and poor root formation in infected setts. The pathogen favors near-neutral and alkaline soils, but its optimal life stage is unknown.
Causes/Conditions Favorable for Wilt Disease in the Field
Symptoms of wilt disease appear during or after the monsoon season, and fungi penetrate plants primarily through wounds caused by pests such as root borer, termites, scales, and mealybugs. In addition to drought, waterlogging, high temperatures, and low humidity also impair the resistance of plants to wilt. These biotic and abiotic stresses make plants susceptible to wilt disease.
Symptoms of Wilt Disease
- After four to five months of plant growth, wilt disease symptoms manifest the gradual withering of canes and yellowing/drying of foliage.
- Longitudinal streaks with discolored purple or dirty reef pith.
- White cottony mycelium in the pith region with an offensive odor.
- Linked to saprophytic bacterial growth and frequently mistaken as causal agents
- After the development phase, the disease manifests as yellowish-green leaves that become brittle and dry at the base.
- Crowns become white or yellow with a delicate green blade.
- Internodes of afflicted canes are stunted, lighter in weight, and hollow, whereas nodes and buds are unaffected.
- Internal nodal tissue is dark red to purple upon longitudinal sectioning above the growth ring.
- Severe conditions significantly reduce yield.
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