potato diseases a lecture on tot training of ffs by mr allah dad khan provincial coordinator ipm...
TRANSCRIPT
Potato Diseases A
Lecture To ToT trainees ( FFS) By
Mr. Allah Dad Khan Provincial Coordinator
IPM KPK MINFAL Pakistan
Late Blight SymptomsOn potato tubers
Symptoms• : Infected potatoes have shallow,
brownish or purplish lesions on the surface of the tuber. If you cut across the surface of these infected areas, you’ll see a reddish-brown, dry, granular rot that extends up to half an inch into the flesh. Late blight lesions can serve as pathways for other tuber diseases including bacterial soft rot to enter, so late blight symptoms can sometimes be obscured by symptoms of other diseases.
Late Blight SymptomsOn potato plants
Symptoms • On potato plants: Late blight lesions can occur on both
leaves and stems. The first appearance of lesions commonly occurs after periods of wet weather. Black lesions appear within 3-7 days of infection of leaves. Under humid conditions, delicate, whitish growth (pathogen spores) are produced at the edge of the lesion, particularly on the underside of the leaf. Lesions turn brown when they dry up. Active lesions are often surrounded by a halo of gray-green tissue. Once lesions dry up, the white spore masses will not be visible. To help identify late blight if outdoor conditions are not humid enough for spores to be produced, you can place suspect leaves or stems in a closed container with a damp paper towel. Check the leaves after about 12 hours to see if the delicate, white pathogen sporulation is visible on the tissue at the edge of the lesion. On stems, late blight causes brown, greasy looking lesions that frequently appear first at the junction between the stem and leaf, or at the cluster of leaves at the top of the stem.
Late blight lesions on potato stems.
Late Blight Late blight lesions on tomato leaflet.
Late Blight on tomato fruit.
Early Blight Symptoms
• Dark lesions with yellow border which may form concentric rings of raised and sunken tissue on the leaves and stems; lesions initially circular but become angular; leaves become necrotic but remain attached to plant; dark, dry lesions on tubers with leathery or corky texture and watery yellow0green margins
• Cause• Fungus
Symptoms of early blight on potato foliage
Early Blight Close-up of leaf lesion caused by early blight
Destruction of potato plants by early blight
Verticillium wilt Verticillium dahliaeVerticillium albo-atrum
Symptoms
• Early death of plants; leaflets dying on only one side of the petiole or branching stem; cut through the stem reveals a discoloration of the tissue; discoloration of tubers at stem-end
• Cause• Fungi
Yellowing potato foliage caused by Verticillium infection
Black scurf & Rhizoctonia canker Rhizoctonia solani
Symptoms
• Flat, irregularly shaped black or dark brown fungal fruiting bodies on tuber surface; tubers may be mishapen; red-brown to black sunken lesions on sprouts; lesions may girdle the main stem causing leaves to curl and turn yellow
• Cause• Fungus
Death of potato plant due to infection with Rhizoctonia
Black scurf & Rhizoctonia cankerRhizoctonia solani
Potato tuber covered with fungal fruiting bodies
Potato tuber covered with fungal fruiting bodies
LeakPythium spp.
• Light tan, water soaked area around wound on tuber; internal rotting of tuber which results in internal tissue becomes spongy and possibly developing cavities; dark, watery fluid exudes from the tuber when squeezed
• Cause• Fungi
• Symptoms
Pink rot Phytophthora erythroseptica
• Stunted plant growth; wilting leaves; dying leaves; marked tuber decay; dark brown eyes on tuber; cut tuber turns pink after 20-30 min air exposure, then turns brown and finally black
• Cause• Oomycete
• Symptoms
Black dotColletotrichum coccodes
• Small black dots (fungal fruiting bodies) on tubers, stolons and stems; roots may rot below ground; leaves may turn yellow and wilt; infection may cause defoliation
• Cause• Fungus
• Symptoms
Powdery scabSpongospora subterranea
Symptoms
• White to brown galls on the roots and stolon; raised pustules on tuber surrounded by potato skin; shallow depressions on tuber filled with brown spores
• Cause• Fungus
Common scabStreptomyces spp.
Symptoms
• Raised brown lesions on tubers with corky texture; deep, pitted brown or black lesions on tuber with straw-colored translucent tissue underneath
• Cause• Bacterium
Tubers showing symptoms of common scab
Blackleg (Soft rot) Erwinia carotovora
Symptoms
• Small, water-soaked lesions on base of stems originating from seed piece; lesions may enlarge to form a large extended lesion stretching from base of stem to canopy; tissue becomes soft and water-soaked and can be lighty brown to inky black in color; wilted, curled leaves which have a soft and slimy texture when wet
• Cause• Bacterium
Soft rot symptoms on potato tubers
Bacterial ring rot Clavibacter michiganensis
symptoms
• Wilting stems and leaves; dying leaves; lower leaves wilting first; ring of creamy yellow to brown rot visible when tuber is cut crossways
• Cause• Bacterium
Cross-section of infected potato tuber showing ring of discolored vascular tissue
Potato leaf roll Potato leafroll virus (PLRV)
Symptoms
• Young leaves rolled and yellow or pink; lower leaves have leathery texture and roll upward; necrotic netting in vascular tissue of tuber may be present; plant exhibits an upright growth habit and growth may be stunted
• Cause• Virus
Potato virus A Potato virus A (PVA)
• Mild mosaic pattern or mottling on leaves; severely infected plants may have alternating patches of yellow and dark green tissue; leaves may have a shiny appearance; stems bending outwards slightly
• Cause• Virus
• Symptoms
Potato virus X Potato virus X (PVX)
• Mild mosaic pattern on leaves; severely infected plants may be dwarved with smaller leaves; necrosis of plant tops and tubers may occur
• Cause• Virus
• Symptoms
Potato virus Y Potato virus Y (PVY)
Symptoms
• Symptoms vary widely from mild mosaic of leaves to leaf necrosis and plant death depending on the variety of potato and the strain of the virus: leaves may turn yellow and drop from plant; symptoms may be present on only one shoot of the plant; plants with severe leaf necrosis may produce tubers with light brown rings on the skin
• Cause• Virus