The document discusses citrus powdery mildew, caused by the fungus Acrosporium tingitaninum. It describes the symptoms, life cycle and management of the disease, which affects citrus trees and can reduce productivity. Powdery mildew is common in parts of Asia and other regions with cool, moist conditions that the fungus favors for growth.

1. CITRUS POWDERY MILDEW
STUDENT
Ms. A. Dhanalakshmi
ID. No. 2015021028
COURSE TEACHER
Dr. PARTHASARATHY S
Asst. Professor., (Plant Pathology)
COLLEGE OF AGRICULTURAL TECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore-3)
Kullapuram (Po),ViaVaigai Dam, Theni-625 562

2. CITRUS POWDERYMILDEW
Causal organism
Acrosporium (oidium) tingitaninum (Carter).

3. DISTRIBUTION
 The disease is common in parts of Asia where it is
prevalent in shady, poorly ventilated orchards.
 There have also been reports from Uganda, Israel,
Central and South America and the united states.
Citrus powdery mildew is not known to occur in
Australia.
 In India, Nilgiris, Palanis, Wynad and Shevoy
hills.

4.  SIGNIFICANCE AND HISTORY
 Severe infection can significantly reduce tree
productivity, fruit quality and yield.
 In India, powdery mildew was first collected
from the Nilgiri hills in 1904, and the Edwin
Butler identified the fungus as Oidium citri.
 Devarajan, Naik and ramakrishnan reported that
powdery mildew caused by Acrosporium
tingitaninum.
 And also they reported that powdery mildew
can be easily controlled by dusting the foliage
with Sulphur.

5. ETIOLOGY
 Comparatively cool and moist fields are prone to
development.
 Damp mornings with only few hours of sunshine
favours onset of the disease.
 The fungus is an ectoparasite, it is a wind borne
disease.

6. SYSTEMIC POSITION
 Kingdom : Fungi
 Division : Ascomycota
 Class : Leotiomycetes
 Order : Erysiphales
 Family : Erysiphaceae
 Genus : Oidium
 Species : O. tingitaninum

7. MODE OF SPREAD:
Primary spread:
Air borne conidia.
Secondary spread:
Ascospores from the infected debris.

8. SYMPTOMS
 Whitish powdery growth appears on young leaves and
twigs.
 In infected leaves get distorted and defoliated in severe
conditions.
 Infected twigs exhibit characteristic die back symptom.
 Young fruits are also covered by whitish powdery mass of
the fungus and drop prematurely resulting in poor yield.

9. Leaves Fruit

10. PATHOGEN
 Hyaline club shaped conidiophore with chain of
barrel shaped conidia arranged in basipetal
succession.
 Sexual fruiting body is chasmothecium which
bears asci and ascospores.

11. LIFE CYCLE
 Dormant mycelia present in the infected parts germinate
and produce oidea during congenial conditions.
 On maturity, barrel shaped conidia are released, which are
air borne and find a host.
 Infection takes through sub- epidermal haustoria and
plant starts producing powdery growth comprising of
oidia

12.  Oidia is an asexual fruiting body of the powdery
mildew and barrel shaped conidia are borne in
chains on oidiophores.
 They release and land on their respective host
through air.
 Infection process continues asexually.

14. MANAGEMENT
 Aerial spray: Bavistin @ 1.25gm/lt, calixin @
1ml/lt and Wettable sulphur @ 3gm/ lt.
 Wider spacing between plants.
 Avoid high density planting.
 Avoid excess N application in the soil.
 Provide recommended dose of potassium.

15. References
 http://agropedia.iitk.ac.in
 ecoursesonline.iasri.res.in/mod/page/view.php
?id=9201