Wilt

Causal Organism: Cephalosporium sacchari

Class: Deuteromycetes

Order: Moniliales

Family: Moniliacease

• This is one of the early known diseases of sugarcane in India.
• It was first reported by Butler and Khan in 1913, from North India.
• It has been reported to cause severe damage to sugarcane crops in many parts of India. During 1965-1967 it caused severe damage to sugarcane crop in the Deccan plateau

Symptoms

The first symptoms of the disease become apparent only when the plant has grown for about 4-5 months. The canes show gradual withering.

• On examination of affected clumps , the pith will be seen discoloured purple or dirty reef, with longitudinal streaks
• The leaves of affected clumps gradually turn yellow and dry up.
• A characteristic disagreeable odour is also associated with such diseased canes.
• A cottony white mycelium can also be seen in the pith region.
• Frequently this fungal disease is associated with a saprophytic bacterial growth and often the bacteria are mistaken as causal agents.

Disease Cycle

• The fungal mycelium is abundant in the infected canes.
• The hyphae are hyaline, thin walled and septate.
• They produce numerous microconidia on simple or branched, lateral or terminal hyphae, but NO macroconidia are produced.
• This is an important character which is distint from that of Fusarium. The conidia are oval to elliptical, and measure 4-12 x 2-3µm in size. They are mostly unicellular, but the ones formed later in the advanced growth of the fungus may be septate
• Conidia readily germinate to produce single germ tubes.
• The fungus is transmitted from place to place through the infected seed setts.
• When the diseased setts are planted, the eyes may fail to develop or often the shoots arising from the eyes may wilt, due to the infection spreading to the shoots.
• Root formation in such setts may be very poor. The fungus can also survive in soil as a saprophyte for 2-3 years.
• Near-neutral and alkaline soils are favoured by the fungus. The perfect stage is not known.

Control

1. The disease is controlled by selecting seed setts from disease free areas.
2. Alkaline soils may be avoided for growing the crop. The setts, selected from disease free stalk, should be dipped in organomercurial fungicide before planting.
3. Dipping the setts in 40 ppm of boron or manganese, or spraying the plants with either of these minor elements reduces the disease intensity.