Kohol rabi Disease A lecture on ToT training of FFS By Mr Allah Dad Khan Provincial Coordinator IPM KPK MINFAL Islamabad
Download as PPTX, PDF0 likes192 views
This document summarizes common diseases that affect kohlrabi crops. It describes 18 different diseases caused by fungi, bacteria, nematodes, and other pathogens. For each disease, it provides information on symptoms, causal organism, and sometimes management strategies. The diseases covered include black rot, black leg, wirestem, Alternaria leaf spot, downy mildew, ring spot, clubroot, Sclerotinia stem rot, white rust, bacterial soft rot, anthracnose, powdery mildew, watery soft rot, and root knot nematode.
Kohol rabi Disease A lecture on ToT training of FFS By Mr Allah Dad Khan Provincial Coordinator IPM KPK MINFAL Islamabad
- 2. Kohlrabi Diseases A Lecture To ToT trainees ( FFS) By Mr. Allah Dad Khan Provincial Coordinator IPM KPK MINFAL Pakistan
- 6. Black rot Xanthomonas campestris Irregularly shaped dull yellow areas along leaf margins which expand to leaf midrib and create a characterstic "V-shaped" lesion; lesions may coalesce along the leaf margin to give plant a scorched appearance Cause Bacteria Comments Pathogen is spread via infected seed or by splashing water and insect movement; disease emergence favored by warm and humid conditions Symptoms
- 7. Black leg Phoma lingam Damping-off of seedlings; round or irregularly shaped gray necrotic lesions on leaves with dark margins; lesions may be covered in pink masses in favorable weather conditions Cause Fungus Comments Favors warm, wet conditions; higher temperatures result in the development of more visible symptoms Management Use disease free seed or treat with hot water to remove fungus prior to planting; remove and destroy crop debris after harvest or plow deeply into soil Symptoms
- 8. Wirestem (Damping-off) Rhizoctonia solani Death of seedlings after germination; brown-red or black rot girdling stem; seedling may remain upright but stem is constricted and twisted (wirestem) Cause Fungus Comments Disease emergence in seedlings favored by cool temperatures Management Plant pathogen-free seed or transplants that have been produced in sterilized soil; apply fungicide to seed to kill off any fungi; shallow plant seeds or delay planting until soil warms Symptoms Constricted stem of broccoli seedling caused by damping-off
- 9. Alternaria leaf spot Alternaria brassicae Small dark spots on leaves which turn brown to gray; lesions may be round or angular and may possess a purple-black margin; lesions may form concentric rings, become brittle and crack in center; dark brown elongated lesions may develop on stems and petioles Cause Fungus Symptoms
- 10. Downy mildew Hyaloperonospora parasitica Small angular lesions on upper surface of leaves which enlarge into orange or yellow necrotic patches; white fluffy growth on undersides of leaves Cause Fungus Symptoms
- 11. Ring spot Mycosphaerella brassicicola Small, purple spots surrounded by a ring of water-soaked tissue on leaves which mature to brown spots with olive green borders 1-2 cm across; spots may develop numerous fruiting bodies which give them a black appearance or develop a concentric pattern; heavily infected leaves may dry up and curl inwards Cause Fungus Symptoms
- 12. Clubroot Plasmodiophora brassicae Slow growing, stunted plants; yellowish leaves which wilt during day and rejuvenate in part at night; swollen, distorted roots; extensive gall formation Cause Fungus Comments Can be difficult to distinguish from nematode damage; fungus can survive in soil for periods in excess of 10 years; can be spread by movement of contaminated soil and irrigation water to uninfected areas Symptoms
- 13. Sclerotinia stem rot (White mold) Sclerotinia sclerotiorum Irregular, necrotic gray lesions on leaves; white-gray leions on stems; reduced pod set; shattering seed pods Cause Fungus Symptoms
- 14. White rust Albugo candida White pustules on cotyledons, leaves, stems and/or flowers which coalesce to form large areas of infection; leaves may roll and thicken Cause Fungus Comments Fungus can survive for long periods of time in dry conditions; disease spread by wind Management Rotate crops; plant only disease-free seed; apply appropriate fungicide if disease becomes a problem Symptoms
- 15. Bacterial soft rot Erwinia caratovora Symptoms Water-soaked lesions on leaves and flower heads which expand to form a large rotted mass; surface of lesions usually crack and exude slimy liquid which turns tan, dark brown or black on exposure to air Cause Bacterium
- 16. Anthracnose Colletotrichum higginsianum Symptoms Small circular or irregularly shaped dry spots which are gray to straw in color on leaves; a high number of spots may cause the leaf to die; lesions may coalesce to form large necrotic patches causing leaves to turn yellow and wilt; lesions may split or crack in dry centers Cause Fungus
- 17. Powdery mildew Erysiphe cruciferarum Small white patches on upper and lower leaf surfaces which may also show purple blotching; patches coalesce to form a dense powdery layer which coats the leaves; leaves become chlorotic and drop from plant Cause Fungus Comments Disease emergence favored by dry season, moderate temperatures, low humidity and low levels of rainfall Management Plant resistant varieties; rotate crops; remove all crop debris after harvest; remove weeds; avoid excessive application of nitrogen fertilizer which encourages powdery mildew growth; powdery mildew can be controled by application of sulfur sprays, dusts or vapors Symptoms
- 18. Watery soft rot (White rot, Cabbage drop) Sclerotinia sclerotiorum Soft rotting area at base of stem which spreads upwards successively killing leaves by causing them to drop and infect the leaf below; when fungus reaches the head it causes a soft, slimy, watery rot Cause Fungus Symptoms
- 19. Root knot nematode Meloidogyne spp. Galls on roots which can be up to 3.3 cm (1 in) in diameter but are usually smaller; reduction in plant vigor; yellowing plants which wilt in hot weather Cause Nematode Symptoms