📈 Diseases of Sugarcane

Sugarcane diseases can sharply reduce cane yield, juice quality, and ratoon performance when infected setts or vectors are not managed early. This lesson focuses on high-impact diseases and practical field-level control measures.

Red Rot

Causal organism: Colletotrichum falcatum (syn. Glomerella tucumanensis)

Red rot is the most devastating disease of sugarcane, sometimes called the "cancer of sugarcane."

Symptoms

• Drying of top leaves with withered appearance
• Internal tissue of cane turns red with white patches across the red area (diagnostic feature)
• Rind shows dark, depressed lesions → pith becomes hollow
• Affected cane emits an alcoholic smell when split open
• Cane juice from infected stalks does not set into jaggery

Disease Cycle

• Pathogen survives in infected setts and stubble
• Spread through irrigation water, rain splash, and red rot-infected setts used as planting material
• Enters through borer holes and cut ends during planting

Management

• Use disease-free, healthy seed cane (most critical)
• Resistant varieties: Co 86032, Co 0238, CoC 671
• Sett treatment with Carbendazim (0.1%) for 15 minutes before planting
• Remove and destroy infected clumps; avoid ratoon from infected fields
• Hot air treatment of setts at 54°C for 2.5 hours

Smut

Causal organism: Sporisorium scitamineum (syn. Ustilago scitaminea)

Symptoms

• Black whip-like structure (sorus) emerging from growing point — the most characteristic symptom
• Whip is 25–100 cm long, initially covered with silvery membrane that ruptures to release black spores
• Infected plants become thin, profusely tillering with grassy appearance
• Severely reduces cane yield and sugar recovery

Management

• Resistant varieties (primary control)
• Hot water treatment of setts at 52°C for 30 minutes
• Rogue out infected clumps before whip opens (prevent spore spread)
• Avoid ratooning in smut-affected fields

Grassy Shoot Disease

Causal organism: Candidatus Phytoplasma (phytoplasma, transmitted by leafhopper Proutista moesta)

Symptoms

• Profuse tillering producing thin, grass-like shoots from the base
• Leaves are pale yellow, narrow, and chlorotic
• No millable canes formed — complete yield loss in severely affected plants

Management

• Disease-free seed material (tissue culture plants)
• Rogue out affected clumps immediately
• Control leafhopper vectors with systemic insecticides
• Hot air treatment of setts at 54°C for 4 hours

Wilt

Causal organism: Fusarium sacchari, Cephalosporium sacchari

• Gradual yellowing and drying of leaves from tip downward
• Internal pith shows brown/purple discoloration
• Common in waterlogged, poorly drained soils
• Management through proper drainage and resistant varieties

Summary Cheat Sheet