Late blight of potato

full details about late blight of potato

1. Late Blight of Potato S.Ramya I M.Sc Microbiology

2. Late Blight of Potato

3. Late Blight of Potato Description: This disease caused by fungus called Phytophthora infestans . The disease may attack almost any time after the crop has put up a fairly good foliage . Initially the lower leaves infected.

4. Late blight Phytophthora infestans Irish famine - 1845-46 Symptoms Leaves, stems and tubers Water soaked spots appear on leaves, turn purple brown & finally black colour White growth develops on under surface Stem breaks at these points and the plant topples

5. In tubers - purplish brown spots & spread to entire surface Tuber show rusty brown necrosis spreading from surface to the center

6. Mode of spread and survival Infected tubers and infected soil - source of primary infection Survival of fungus in fruiting stage or as dormant mycelium in the soil Persisting of perennial mycelium in affected tubers from the field, stored and used as seed in next season Epidemiology Cool (12 to 15 o C) and humid ( above 90 %) weather with rains alternating with warm (20 o C) moist period

7. Fungus Mycelium - endophytic , coenocytic and hyaline Sporangiophores – arise from internal mycelium through stomata on the tubers Sporangia - multinucleate, thin walled, hyaline, oval shaped Zoospores - biflagellate Phytophthora infestans A, zoospores produced within the lemon-shaped sporangia ( B ).

8. Control measures S . demissum and S . phureja - used for breeding for disease resistant varieties Varieties - Kufri Naveen , Kufri Jeevan , Kufri Alenkar , Kufri Moti Bruising of tubers at harvest should be avoided Regular spraying during growing season gives effective control- 10 to 15 days interval Brestan 600g/ha Zineb 0.2 % Bordeaux mixture 1.0% Mancozeb (2 kg/ha)