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Chilli dieback and fruit anthracnose (Colletotrichum)

Anthracnose and twig dieback of chilli is caused principally by Colletotrichum capsici and related Colletotrichum species. The disease is one of the most economically damaging foliar and fruit pathogens of the Indian chilli crop, causing both pre-harvest pod rot and terminal twig death ('dieback').

Identification and symptoms

On ripening fruit the pathogen produces small dark sunken circular spots that enlarge, bleach to a straw colour, lose pungency and bear concentric rings of acervuli. Severe infections also kill terminal twigs, producing the dieback phase from which the disease takes one of its names.

Host crops / Life cycle

The principal causal agent is Colletotrichum capsici, with C. truncatum and C. gloeosporioides also reported in Indian crops. The disease is seed-, soil-, water- and air-borne, with conidia spread by rain splash. Optimum disease development occurs at around 28 deg C and relative humidity above 95%, typically after post-fruit-set rain. Hosts include all chilli segments — the Guntur, Teja and Byadgi types (Chilli Guntur Sannam, Chilli Teja Segment, Chilli Byadgi Segment).

Damage and economic impact

India loses an estimated ~29.5% of annual chilli production to this disease, with economic cost estimated at approximately US$ 491 million per year.

Management (cultural, biological, chemical)

  • Seed treatment — thiram at 2 kg/ha or zineb at 2.5 kg/ha
  • Sprays — TNAU recommends three captan 0.2% sprays starting at flowering; difenoconazole at 0.025% gave the lowest disease intensity (21.13%) among single fungicides in published Indian trials, with azoxystrobin and mancozeb also effective
  • Resistance sources — PBC 932, Breck-1/2 and BS-35 are used as donors in breeding programmes
  • Calendar fit — anthracnose sprays are integrated into the second-flush window of the standard IPM schedule (Practice Chilli Spray Schedule)
  • Post-harvest — prompt drying (Practice Chilli Picking Drying) limits secondary spread

Chilli Fruit Rot Anthracnose, Practice Chilli Spray Schedule, Practice Chilli Picking Drying, Chilli Guntur Sannam

References

  1. Chilli anthracnose / fruit rot. TNAU Agritech crop protection page.
  2. Chilli Anthracnose: Epidemiology and Management. Frontiers in Microbiology, 2016.