Diseases on pea
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a brief description on diseases of pea their symptom and casual organism. Content is for eduacational purpose and truly for students ,scientist and farmers. students presentation
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Diseases on pea
- 1. A powerpoint presentation by- Punam Lakra Vandana Medihare
- 3. CONTENTS S.NO. PARTICULARS 1. LIST OF DISEASES IN PEA 2. NOTE ON DISEASES 3. IDM STRATEGIES ON DISEASES OF PEA
- 4. LIST OF DISEASES S.NO. DISESASES CAUSAL ORGANISM 1. Ascochyta blight/Black Spot Ascochyta pinnodes,Ascochyta pinodella and Ascochyta pisi 2. Fusarium Wilt Fusarium oxysporum fsp. pisi 3. Downey Mildew Peronospora pisi 4. Powdery Mildew Erysiphe polygoni 5. Bacterial Blight Pseudomonas pisi 6. Early Browning of pea Pea Early Browning Virus 7. Pea Enation Mosaic Pea Enation Mosaic Virus
- 5. PEA DISEASES Peas are subject to a number diseases,several of which may cause serious injury or loss.Annual losses from diseases vary from year to year,depending often on local weather conditions. If the soil is wet from excessive rains and the weather is cool,heavy losses may be expected from root rots and from such diseases as Ascochyta and bacterial blights. If the soil is badly infested with root rotting organisms, total loss may result.
- 6. ASCOCHYTA BLIGHT Introduction Ascochyta blight is caused by 3 pathogens(Ascochyta pinnodes,Ascochyta pinodella and Ascochyta pisi) those occur as a complex in the field. The ascochyta blight disease complex affects field peas (Pisum sativum), as well as many other legumes such as chick peas, lentils, and faba beans.
- 7. SYMPTOMS: Ascochyta blight is characterized in part by the formation of black to purplish streaks on the stem. The lesions are more conspicuous at the nodes and enlarge into brown or purplish irregularly shaped areas scattered indiscriminately from the roots to 10 inches or more up the stem. The spots may be very small, purplish, and very irregular in shape and size, or they may be fairly large and more or less circular.
- 8. Under favorable conditions, the entire leaf of a very susceptible variety may be so badly injured that it shrivels and dries up. The symptoms on the pods are similar to those on the leaves, except that the spots on the pods are sunken and have no concentric circles.
- 9. Disease Cycle The fungi that cause ascochyta blight may either be seed borne, soil borne or survive in pea trash. The disease usually becomes established when sexual ascospores of the fungus (A. pinodella), produced in perithecia on old pea stubble, are carried into the new crop by rain and wind causing early infection. Asexual conidia are produced by other pathogens in pycnidia (fruiting bodies) and can infect pea plants at any stage of plant growth.
- 10. Ascospores are the main source of primary infection, whereas the secondary infection is caused by production of conidia. Discharge of both types of spores needs rainfall or dew therefore epidemics are more severe in wetter conditions. Spores produced on infected foliage are transferred onto adjacent healthy plants by wind and rain splash.
- 11. Management Use Clean Seed Destroy Old Pea Crop Residues Rotate crops so there is at least 3 years between Pea crops and often 4 or 5 years may be required. Follow the recommended sowing rates and sowing dates for your district. Avoid early sowing at high seeding rates. Don’t mix fungicide with inoculants as this will reduce the number of rhizobia. Apply all foliar fungicide sprays before rain.
- 12. FUSARIUM WILT Introduction Fusarium wilt of peas is caused by a fungus(Fusarium oxysporum fsp. pisi) that is very similar to organisms causing wilt in a number of other cultivated plants, including tomato, sweet potato, cotton, cowpea, water- melon, and cabbage. Wilt-affected plants are more difficult to pull from the soil than those damaged or killed by root rots
- 13. SYMPTOMS: Plants may become infected at any stage of growth.The first symptoms are usually a yellowing of the lower leaves and a stunting or dwarfing of plant growth. The stipules and margins of the leaflets curl downward and inward. The stems at or near the soil line may be slightly thickened and brittle. The lower stem shows black discoloration of the water- conducting tissue (xylem) within the stem. Affected plants may wilt and die either slowly or rapidly soon after the first symptoms are noted due to destruction of the feeder roots.
- 14. Disease cycle Fusarium oxysporum is a common soil pathogen and saprophyte that feeds on dead and decaying organic matter. It survives in the soil debris as a mycelium and all spore types, but is most commonly recovered from the soil as chlamydospores. This pathogen spreads in two basic ways: it spreads short distances by water splash, and by planting equipment, and long distances by infected transplants and seeds. F. oxysporum infects a healthy plant by means of mycelia or by germinating spores penetrating the plant’s root tips, root wounds, or lateral roots.
- 15. MANAGEMENT: Clean cultivation Use of certified seeds only. A 5-year rotation or longer, using crops other than peas, The prevention of movement of all pea vine debris to other fields, will help to prevent buildup of wilt fungi in the soil. Resistant variety-Norli,Lincoln
- 16. DOWNY MILDEW Downy mildew of pea is caused by Peronospora pisi Sydow, whose mycelium consists of aseptate, branched,hyaline hyphae, confined to the intercellular spaces of the host tissues.
- 17. Symptoms of Downy Mildew of Pea: 1) Yellow to brown scattered patches of discoloured areas appear on the upper surface of the leaflets and stipules. Simultaneously with this, downy growth in patches of variable size are visible on the under surface corresponding with the lesions of the upper surface. The downy coating is whitish when young, but the colour gradually turns greyish-violet with age. 2) When young,the blotches on the pods are pale-green, more or less elliptical to irregular, but gradually the blotches turn dark to bright-brown, mottled with light- green islands. 3) Blotch followed by the green island effect is a typical symptom of the disease.
- 18. Disease Cycle- Cool humid condition is very favourable for the development of the disease, while the disease incidence is slowed down with warm condition.This is due to the fact that the sporangia which behave as conidia spread the disease, but cannot stand desiccation. The sporangia are blown about freely by the wind and spread the disease rapidly from plant to plant.
- 19. Management- 1) Since the causal organism survives from season to season in the form of oospores in the plant debris, the destruction of previous year’s plant debris and following crop rotation of two or three years are very effective control measures. 2) Spraying and dusting pea plants with fungicides are effective in limiting the spread of the disease. 3) Deep tillage to bury crop residues. 4) Use tolerant cultivars. 5) Use metalaxyl for seed treatment.
- 20. POWDERY MILDEW The powdery mildew of peas is worldwide in occurrence causing serious losses to the crop. The disease is considered to be much more serious than the downy mildew of peas. In India, the disease generally appears during November- December.
- 21. Symptoms of Powdery Mildew Disease: 1) First symptoms appear on the leaves in the form of white floury patches on both sides of leaves. The disease then spreads to other green parts of the plant such as tendrils, pods, stems etc. The patches on the leaves originate in the form of minute discoloured specks from which powdery mass radiates on all sides. 2) In the advanced stages of the disease large areas of the host get coveted with white floury patches. Infected plants impart dirty appearance. 3) In extreme severe infections the infected leaves are shed leaving stem devoid of the leaves.
- 22. DISEASE CYCLE OF POWDERY MILDEW Primary source of infection-Infected debris Secondary source of infection-wind blown conidia Fungus survives in summer leftover debris. Seed is not considered as main source of inoculum.
- 23. •Management- Avoid late planting. After harvest, collect the plants left in the field and burn them. By formulation of wettable Sulphur such as Sulfex and Thiovit at 3 kg/ha. 0.03 % Calixin followed by Karathane (0.2%) and Bavistin (100 ppm) Grow resistant varieties like JP-83, PM-2, JP-4, and JRS-14.
- 24. BACTERIAL BLIGHT Introduction This disease, caused by the bacteria Pseudomonas syringae pv. pisi , is a serious disease of peas.
- 25. Symptoms This disease affects all above-ground plant parts. Seedlings from infected seed may die. The affected leaflets have small, round, oval or irregular spots of reddish brown colour with translucent centre with a darker brown margin. Several spots merge to produce blight appearance. Chocolate brown linear streaks on stems and petioles. Pods are chocolate brown, thin, twisted and shriveled. Pod surface are glossy due to dried bacterial ooze. Seeds become discoloured and shriveled.
- 26. Disease Cycle Bacterial blight commonly becomes established within a field by sowing infected seed or from infected pea trash that is nearby. During wet weather, bacteria spread from infected to healthy plants by rain splash and in wind-borne water droplets. The pathogens can remain on the surface of plants without causing symptoms. However, following rain, heavy dew, frost or other forms of damage to plant tissues, symptoms can develop.
- 27. MANAGEMENT: Always sow healthy seeds procured from disease-free crop or certified seeds. Invariably discard discoloured and shrivelled seeds and give a pre-sowing seed dip in Streptocycline solution (1g/10 liters of water) for 1-2 hours. Give a spray of Streptomycin (0.01%) on appearance of first symptoms of the disease and repeat after 7 days, if necessary. Follow a 3 years crop rotation. Practice sanitation, keep proper drainage and give appropriate spacing between plants.
- 28. PEA EARLY BROWNING Pea early browning virus (PEBV) is a plant pathogenic virus. Pea early browning virus (PEBV) is a member of the genus, Tobravirus. It is transmitted by soil-inhabiting trichodorid nematode(Paratrichodorus anemones) and through seeds from diseased plants.
- 29. List of symptoms/signs 1) Leaves - abnormal colours 2) Leaves - abnormal patterns 3) Leaves - necrotic areas 4) Seeds - discolorations 5) Whole plant - dwarfing 6) Whole plant - early senescence 7) Advanced symptoms in the crop show as brown patches of poor growth, particularly when infection with PEBV occurs early in the season (Bos and van der Want, 1962)
- 30. Management- 1. Removal of infected seeds. 2. Use healthy disease free certified seeds. 3. Avoid cultivation in land with vector infested soil.
- 31. PEA ENATION MOSAIC VIRUS Pea enation mosaic virus (PEMV) is a plant pathogenic virus. The two RNAs of the disease are now categorised as two separate, mutualistic viruses: PEMV-1 is an Enamovirus, while PEMV-2 is anUmbravirus. It is spread by pea aphid (Acyrthosiphon pisum) and to a lesser extent by the green peach aphid (Myzus persicae). Also affects legumes as pea, alfalfa, broadbean or sweet pea mostly in temperate regions. There are 8 total species known to transmit PEMV.
- 32. Symptoms- It includes chlorotic, translucent or necrotic lesions, malformation of leaves and stipules, and plant distortion.The most characteristic symptom is the formation of enations on the abaxial. Enations are derived from the cells of vascular bundles undergoing hyperplasia.
- 33. Cultural and Physical Control measures- 1) Use of resistant(Oregon pioneer) or tolerant cultivars. 2) If using susceptible varieties, planting before March 31 helps avoid aphid infestation. 3) Spray water to knock aphids off plants. Biological Control measures- 1) Green peach aphid or pea aphid predators and parasites can be used to prevent an outbreak of PEMV. The most common enemies of these aphids are: 1. Lady bird beetles(Coleoptera: Coccinellidae) 2. Flower flies (Diptera: Syrphidae) 3. Lacewings (Neuroptera: mainly Chrysopidae) 4. Parasitic wasps (Hymenoptera: Braconidae). No chemical control measures have been recommended yet.
- 34. IDM STRATEGIES ON DISEASES OF PEA IDM includes- 1. Use of moderately resistant. varieties(Avalanche,Sugar Bon,Sugar sprint),tolerant varieties(Bolero),disease free seed. 2. Crop rotation. 3. Delay in the sowing. 4. Disease forecast model that predicts the time of onset and progression of ascospores maturity and spread of spores from the source of infection. 5. Need based foliar and in-furrow applications of fungicides in conjunction with other agronomic practices (Kraft et al., 1998).