Cucurbits powdery mildew

Cucurbits powdery mildew

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 P rimary : 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 F ungicides 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 .