Powdery mildew is caused by the fungi Podosphaera xanthii and Erysiphe cichoracearum. It affects cucurbit plants like cucumbers and melons. Symptoms include white or gray powdery spots on leaves that spread and cause defoliation and reduced fruit yield. The disease spreads via airborne conidia or ascospores. Management strategies include using resistant varieties, removing weeds, and applying preventative fungicides under favorable warm, humid conditions.

1. CUCURBITS POWDERY MILDEW
SUBMITTED BY: COURSE TEACHER
J. PRAKASH Dr. S.PARTHASARATHY
2015021097 Asst. Prof. (Plant Pathology)

2. CUCURBITS POWDERY MILDEW
CAUSAL ORGANISM : Podosphaera xanthii and
Erysiphe cichoracearum

3. SYSTEMATIC CLASSIFICATION
• Kingdom : Fungi
• Phylum : Ascomycota
• Class : Leotiomycetes
• Subclass : Leotiomycetidae
• Order : Erysiphales
• Family : Erysiphaceae
• Genus : Erysiphe
• Species : Erysiphe cichoracearum

4. SYMPTOMS
 Upper surface small white or greyish superficial spots later covered by
fungal growth.
 Powdery mildew symptoms first appear as pale, chlorotic spots on
leaves that soon turn powdery-white in appearance (fungal spores) and
spread to petioles and stems.
 Defoliation occurs.
 Fruits are small and yield reduced.

5. SYMPTOM ON LEAF

6. PATHOGEN DESCRIPTION
 Conidia are single celled, hyaline barrel-shaped and in log chains.
 Chasmothecium are globose and dark brown myceloid appendages.
 Asci are pedicellate, and ovate. Ascospores are single, hyaline oval to sub
cylindrical.

7. DISEASE CYCLE
 Sexual reproduction is via chasmothecia, a type of ascocarp
where the genetic material recombines.
 Powdery mildew fungi must be adapted to their host to be
able to infect them, within the ascocarp are several asci.
 Under optimal condition, ascospores mature and are released
to initiate new infection.

8. CONIDIA

9. FAVOURABLE CONDITION
 Over a range of humidity (50 to 95 %) during moderate
to warm climate.
 Temperature around – 68 to 80 F.

10. MODE OF SPREAD
• Primary : Ascospores from infected plant debris.
• Secondary : Wind borne conidia

11. MANAGEMENT
Cultural practices
 Eliminate weed in and around cucurbit field.
 Resistant cucumber and melon varieties are available
and should be planted.

12. BIOLOGICAL METHOD
 AQ10 biofungicide is a fungal hyperparasite (Ampelomyces
quisqualis) of the powdery mildew fungus.
 AQ10 must be applied preventatively along with a mineral-oil or
silicone surfactant early in the morning or later at night.
 Other fungicides are not applied when AQ10 is used.

13. CHEMICAL CONTROL
 Fungicides such as triadimefon and propiconazole,
effective chemical control is also possible with
hexaconazole, penconazole.
 Another chemical treatment involves treating with a
silicon solution or calcium silicate slag.
 New generation fungicides used to control cucurbits
powdery mildew is vivando.