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Powdery mildew - Erysiphe cichoracearum (Syn: Oidium acanthospermi)

Initially greyish-white powdery growth appears on the upper surface of leaves. When several spots coalesce, the entire leaf surface may be covered with powdery coating. In severe cases, the infection may be seen on the flowers and young capsules, leading to premature shedding. The severally affected leaves may be twisted and malformed. In the advanced stages of infection, the mycelial growth changes to dark or black because of development of cleistothecia

Erysiphe cichoracearum - Symptoms 1
Erysiphe cichoracearum - Symptoms 2

The Pathogen produces hyaline, septate mycelium which is extophytic and sends haustoria into the host epidermis. Conidiophores arise from the primary mycelium and are short and non septate bearing conidia in long chains. The conidia are ellipsoid or barrel-shaped, single celled and hyaline. The cleistothecia are dark, globose with the hyaline or pale brown myceloid appendages. The asci are ovate and each ascus produces 2-3 ascospores, which are thin walled, elliptical and pale brown in colour.
Favourable Conditions

  • Dry humid weather.
  • Low relative humidity.

Disease Cycle
The Pathogen is an obligate parasite and disease perennates through cleistothecia in the infected plant debris in soil. The ascospores from the cleistothecia cause primary infection. The secondary spread is through wind-borne conidia.

  • Remove the infected plant debris and destroy.
  • Spray wettable sulphur at 2.5 kg/ha or karathane 1L/ha repeat after 15 days.