Late blight of potato.pptx

Late blight of potato- Agricultural Plant disease
by- Nidhi Patel
B.Sc, M.Sc Microbiology

1. Late blight of potato Agriculture plant diseases

2. description Late blight of potato is identified by  blackish/brown lesions on leaves and stems that may be small at first and appear water-soaked or have chlorotic borders but expand rapidly and the entire leaf becomes become necrotic.  Late blight ( phytophthora infestans ) fungus is in the same genus as the fungus causing pink rot . Blight can spread very quickly, carried by wind and rain . 

3. Phytophthora infestans   Phytophthora infestans is an oomycete or water mold, a fungus-like microorganism that causes the serious potato and tomato disease known as late blight or potato blight.   Early blight, caused by alternaria solani , is also often called "potato blight".  The organism can also infect some other members of the  solanaceae . The pathogen is favored by moist, cool environments: sporulation is optimal at 12–18 °c (54–64 °f)

4. Systematic position Phytophthora infestans Order: Peronosporales Family: Peronosporaceae Genus: Phytophthora Species: P. infestans

5. Symptoms damages leaves , stems and tubers  Affected leaves appear blistered as if scalded by hot water and eventually rot and dry out . When drying out , leaves turn brown or black in color.  Affected stems begin to blacken from their tips , and eventually dry out . Severe infections cause all foliage to rot , dry out and fall to the ground, stems to dry out and plants to die. Affected tubers display dry brown-colored spots on their skins and flesh. This disease acts very quickly. If it is not controlled, infected plants will die within two or three days .

6. Symptoms Dry rot Wet rot Dry and brittle timber appearance Wet and spongy to the touch There may be orange spore dust Affected timbers will appear darker White strands on timbers Localised fungal growth White or grey cloud-like structures on timbers Affected timber is vulnerable to shrinkage Rusty brown fruiting bodies More likely to be accompanied by a damp, musty smell

7. Spread of late blight potato The spores are carried by wind and rain to healthy plants, where the disease cycle begins again. A disease cycle can occur every five to seven days, resulting in rapid spread and movement of late blight. Tubers are infected by spores washed from lesions to the soil .

8. Survival from late blight potato Use potato tubers for seed from disease-free areas to ensure that the pathogen is not carried through seed tuber . The infected plant material in the field should be properly destroyed. Grow resistant varieties like Kufri Navtal . Fungicidal sprays on the appearance of initial symptoms.

9. Epidemiology   Cool (12 to 15°C ) and humid ( above 90 %) weather with rain alternating with warm ( 20° C) moist period.

10. 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

11. Life cycle of potato late blight

12. Use of healthy seed  Removal of plant debris (field sanitation)  Removal of weeds Harvesting in dry season   Harvesting after ripining   Remove upper portion before 15 days of harvesting  Earthing - 10-15 cm Control measure of late blight of potato