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Peanut bud necrosis disease (PBND) Photo: Thamizhpparithi Maari · CC BY-SA 4.0 · source ↗

Peanut bud necrosis disease (PBND)

Peanut bud necrosis disease (PBND) is the single most damaging viral disease of groundnut in peninsular India. It is caused by Peanut bud necrosis virus (PBNV), now classified as Groundnut bud necrosis orthotospovirus in the family Tospoviridae. The virus is transmitted by thrips, principally Thrips palmi, and outbreaks routinely cause 20-90 percent yield loss in Anantapur, Kurnool, Mahabubnagar and Chittoor kharif groundnut, with total crop failure on severely affected fields.

Identification and symptoms

Initial symptoms are chlorotic spots and ring-spots on young leaves, followed by necrosis of the terminal bud (the characteristic feature). Infected plants are stunted; axillary shoots are forced out giving a bushy bunched appearance. Late infection produces small distorted leaves on the upper canopy with brown necrotic streaks on the petioles and stems. Pods on diseased plants are small, malformed and often empty. The disease is field-diagnosable from the necrotic terminal bud combined with the chlorotic ring patterns on lower leaves.

Hosts and lifecycle

PBNV has a wide host range covering more than 30 crop species — groundnut, sunflower, tomato, chilli, mungbean, urdbean, pigeonpea, sesame and many weeds (Amaranthus, Datura, Tagetes, Trianthema). The virus survives between groundnut seasons on weed hosts and on alternate crops, especially summer chilli and tomato in Anantapur and Chittoor. Thrips (T. palmi, Frankliniella schultzei, Scirtothrips dorsalis) acquire the virus as larvae from infected plants and transmit it persistently as adults. Sowing groundnut alongside thrips-favourable conditions — hot dry weather, sparse rain, dense weed flora — drives the epidemic.

Economic impact

In Anantapur, ICAR-DGR and ICRISAT surveys have reported PBND incidence of 30-80 percent in late-sown rainfed groundnut during kharif breaks (extended mid-season dry spells). Yield loss is approximately equal to the percentage of plants infected at less than 30 DAS; infection after 60 DAS causes negligible yield loss. PBND is the single biggest reason for replanting demand among Anantapur farmers and underpins much of the Rythu Bharosa kharif compensation pressure.

Management

  • Resistant/tolerant varieties: ICGV 86388 (ICGS 11), ICGV 86590, ICGS 44, Narayani and Dharani show useful field tolerance; Kadiri-6 is moderately susceptible.
  • Cultural: timely sowing with the onset of southwest monsoon; avoid staggered sowing; close spacing (30 x 10 cm) to reduce thrips entry; intercrop with pearl millet (1:7) which acts as a barrier; rogue out infected plants within 30 DAS.
  • Vector management: seed treatment with imidacloprid 600 FS at 8 ml/kg seed protects up to 30-40 DAS. Foliar sprays of fipronil 5 SC at 1.5 ml/L or spinosad 45 SC at 0.4 ml/L at 25 and 40 DAS suppress thrips populations when monitoring shows threshold (>5 thrips/leaf).
  • Weed and inoculum management: clean weed flora in and around the plot; avoid sowing groundnut next to summer chilli or tomato; remove volunteer plants.

See also: Groundnut Crop, Kadiri 6 Groundnut, Dharani Groundnut, Tikka leaf spot in groundnut, Groundnut rust.

Sources

  1. Bud necrosis disease of groundnut. ICRISAT, Patancheru.
  2. Management of bud necrosis disease of groundnut. ICAR-Directorate of Groundnut Research, Junagadh.
  3. Peanut Bud Necrosis Tospovirus. CABI Compendium.