Powdery mildew of papaya

PAT 401

1. COLLEGE OF AGRICULTURAL TECHNOLOGY ( (Affiliated to Tamil Nadu Agricultural University, Coimbatore-3) kullapuram (Po), ViaVaigai Dam, Theni-625 562 PAPAYA POWDERY MILDEW STUDENT COURSE TEACHER J.M. Harishkumar Dr.PARTHASARATHY.S Asst.Prof .,(Plant Pathology)

2. Diseases name: P apaya Powdery Mildew Pathogen name: Oidium caricae

3. HISTORY: Carica papaya - Native distribution of papaya ranges from Mexico Odium caricae introduced by Noack (1898) Powdery mildew occurs throughout the world where conditions are relatively warm and moist

4. Systematic position : Kingdom: Fungi Division:Ascomycota Class: Leotiomycetes Order: Erysiphales Family : Erysiphaceae Genus: Oidium Species: Oidium caricae pv . papayae

5. Infected leaves Infected Infected fruit @ agritech.tnau.ac.in I infected leaf

6. SYMPTOMS: On the upper surface of disease of leaves are found patches of whitish powdery growth occurs The disease appear on the foliage and pods Occasionally fungus may attack the stem of young seedling when grown under reduced light condition. The spots enlarge and cover the entire leaf area. Severely infected leaves may become chlorotic and disorted before falling.

7. Fungus: It is o bligate parasite The mycelium is hyaline septate and haustoria develop in epidermal cells Conidia are hyaline, granular in type

8. Favourable conditions: Temperature: Moderate (24-26 degree celcius ) Relative Humidity: Greater than 80- 85% Optimum moisture conditions for plant growth Low light intensity Black soil, clay soil

9. Mode of spread: The fungus spreads through wind borne conidia The powdery mildew fungus overwinters in dormant buds Secondary spread of the disease can occur if spores are produced in these new infections

10. Disease cycle: The fungus overwinters in infected leaves on the ground and possibly in diseased shoots The overwinters spore (oospore) germinates in the springs and produces a different type of spore (sporangium) The sporangia are spread by wind and splashing rain

11. When plant parts are covered with a flim of moisture the sporangia release smell swimming spores called zoospore Zoospore germinate by producing a germ tube that enters the leaf through stomates on the lower leaf surface

12. Treatment and control : Do not irrigate with overhead sprinklers. Ensure balanced nutrition and avoid high nitrogen fertilizattion . Wettable sulphur , sulphur dust, or lime sulfur as well as potassium bicarbonate is helps to control the disease. Sometimes backing powder, neem oil extracts and soap solution can be useful.

13. References : http://www.fftc.agenet.diseases Saha L.R. handbook of plant disease, 2002, Kalyani publishers , New Delhi.(pg.no.98-123)