PPA End term Diseases (Field Crops).docx

Wheat +-------------+-------------+-------------+-------------+-------------+ | Disease | Causal | Systematic | Concise | Important | | Name | Organism | Position | Disease | Management | | | (Teleomorph | and | Cycle | Practice | |...

Wheat +-------------+-------------+-------------+-------------+-------------+ | Disease | Causal | Systematic | Concise | Important | | Name | Organism | Position | Disease | Management | | | (Teleomorph | and | Cycle | Practice | | | /Anamorph) | Etiology | | and | | | | | | Chemical | | | | | | Control | +=============+=============+=============+=============+=============+ | **Stem | Puccinia | D: | Urediniospo | \- Destroy | | rust** | graminis f. | Basidiomyco | res | alternate | | | sp. tritici | ta | (from | host | | | (Teleomorph | C: | infected | (barberry) | | | : | Pucciniomyc | wheat | | | | Puccinia | etes | debris | \- | | | graminis) | O: | reach | Chemical: | | | | Pucciniales | healthy | Tebuconazol | | | | F: | plant | e | | | | Pucciniacea | through | (250g/ha) | | | | e | wind) | at early | | | | | infect | disease | | | | **Obligate | wheat → | onset. | | | | biotrophic | pustules | | | | | fungus** | form on | | | | | | stem and | | | | | | leaf sheath | | | | | | → | | | | | | teliospores | | | | | | overwinter | | | | | | (on plant | | | | | | debris) → | | | | | | basidiospor | | | | | | es | | | | | | infect | | | | | | alternate | | | | | | host | | | | | | (barberry) | | | | | | → | | | | | | aeciospores | | | | | | reinfect | | | | | | wheat. | | +-------------+-------------+-------------+-------------+-------------+ | **Leaf | Puccinia | D: | Urediniospo | \- Early | | rust** | triticina | Basidiomyco | res | sowing | | | (Syn: P. | ta | (from | | | | recondita | C: | volunteer | \- | | | f. sp. | Pucciniomyc | wheat reach | Chemical: | | | tritici) | etes | healthy | Propiconazo | | | | O: | plant | le | | | | Pucciniales | through | (0.1%) at | | | | F: | wind) | first sign | | | | Pucciniacea | infect | of disease | | | | e | wheat → | | | | | | pustules | | | | | **Obligate | form on | | | | | biotrophic | leaves → | | | | | fungus** | teliospores | | | | | | rarely | | | | | | formed → | | | | | | urediniospo | | | | | | res | | | | | | overwinter | | | | | | (on | | | | | | volunteer | | | | | | wheat). | | +-------------+-------------+-------------+-------------+-------------+ | **Yellow | Puccinia | D: | Urediniospo | \- Avoid | | rust** | striiformis | Basidiomyco | res | late sowing | | | f. sp. | ta | (from | | | | tritici | C: | volunteer | \- | | | | Pucciniomyc | wheat reach | Chemical: | | | | etes | healthy | Propiconazo | | | | O: | plant | le | | | | Pucciniales | through | (0.1%) at | | | | F: | wind) | first sign | | | | Pucciniacea | infect | of disease | | | | e | wheat → | | | | | | stripe-like | | | | | Obligate | pustules | | | | | biotrophic | form on | | | | | fungus | leaves and | | | | | | glumes → | | | | | | urediniospo | | | | | | res | | | | | | overwinter | | | | | | (on | | | | | | volunteer | | | | | | wheat) → | | | | | | wind | | | | | | dispersal. | | +-------------+-------------+-------------+-------------+-------------+ | **Loose | Ustilago | D: | Teliospores | \- Hot | | smut** | tritici | Basidiomyco | (from | water seed | | | | ta | infected | treatment | | | | C: | heads reach | (52°C for | | | | Ustilaginom | healthy | 10 min) | | | | ycetes | plant | | | | | O: | through | \- | | | | Ustilaginal | wind) | Preventive | | | | es | infect | Seed | | | | F: | wheat at | treatment: | | | | Ustilaginac | flowering → | Carboxin + | | | | eae | mycelium in | Thiram | | | | | seed embryo | (2g/kg | | | | **Systemic | → fungus | seed) | | | | fungus** | overwinters | | | | | | (in seed | | | | | | embryo) → | | | | | | systemic | | | | | | growth → | | | | | | infected | | | | | | head with | | | | | | smut | | | | | | spores. | | +-------------+-------------+-------------+-------------+-------------+ | **Karnal | Tilletia | D: | Teliospores | \- | | bunt** | indica | Basidiomyco | (from soil | Quarantine | | | (Syn: | ta | reach | measures to | | | Neovossia | C: | healthy | prevent | | | indica) | Ustilaginom | plant | spread. | | | | ycetes | through | | | | | O: | wind) | \- Adjust | | | | Tilletiales | germinate → | sowing date | | | | F: | basidiospor | to avoid | | | | Tilletiacea | es | favorable | | | | e | infect at | conditions | | | | | flowering → | | | | | **Soil-born | local | | | | | e | infection | | | | | fungus** | in kernels | | | | | | → | | | | | | teliospores | | | | | | overwinter | | | | | | (in soil | | | | | | and on seed | | | | | | surface). | | +-------------+-------------+-------------+-------------+-------------+ | **Powdery | Blumeria | D: | Conidia | \- Avoid | | mildew** | graminis f. | Ascomycota | (from | excess | | | sp. tritici | C: | infected | nitrogen | | | (Syn: | Leotiomycet | plant | | | | Erysiphe | es | debris | \- | | | graminis & | O: | reach | Chemical: | | | Anamorph: | Erysiphales | healthy | Triadimefon | | | Oidium | F: | plant | (0.1%) at | | | monilioides | Erysiphacea | through | first sign | | | ) | e | wind) | of disease | | | | | infect | | | | | **Obligate | leaves → | | | | | biotrophic | white | | | | | fungus** | powdery | | | | | | growth on | | | | | | leaves, | | | | | | stems, and | | | | | | heads → | | | | | | cleistothec | | | | | | ia | | | | | | form and | | | | | | overwinter | | | | | | (on plant | | | | | | debris). | | +-------------+-------------+-------------+-------------+-------------+ | **Alternari | Alternaria | D: | Conidia | \- Crop | | a | triticina | Ascomycota | (from crop | rotation | | blight** | | C: | residues | | | | | Dothideomyc | reach | \- | | | | etes | healthy | Chemical: | | | | O: | plant | Mancozeb | | | | Pleosporale | through | (0.25%) | | | | s | wind) | preventivel | | | | F: | infect | y | | | | Pleosporace | leaves → | or at early | | | | ae | oval to | disease | | | | | elongated | onset. | | | | **Necrotrop | lesions | | | | | hic | form on | | | | | fungus** | leaves → | | | | | | sporulation | | | | | | on lesions | | | | | | → conidia | | | | | | overwinter | | | | | | (on crop | | | | | | residues) → | | | | | | secondary | | | | | | spread. | | +-------------+-------------+-------------+-------------+-------------+ | **Ear | Anguina | P: Nematoda | Juveniles | Hot water | | cockle** | tritici | C: | (from galls | treatment | | | (Wheat seed | Chromadorea | in soil | of seed | | | gall | O: | reach | (54°C for | | | nematode) | Tylenchida | healthy | 10 min). | | | | F: | plant | | | | | Anguinidae | through | Preventive | | | | | irrigation | seed | | | | Etiology: | water) | treatment: | | | | **Plant-par | enter wheat | Carbosulfan | | | | asitic | seedlings → | (3% a.i.). | | | | nematode** | move to | | | | | | developing | | | | | | ear → form | | | | | | galls | | | | | | instead of | | | | | | grains → | | | | | | juveniles | | | | | | overwinter | | | | | | (in galls | | | | | | in soil). | | +-------------+-------------+-------------+-------------+-------------+ Sugarcane +-------------+-------------+-------------+-------------+-------------+ | Disease | Causal | Systematic | Concise | Important | | Name | Organism | Position | Disease | Management | | | (Synonyms, | and | Cycle | Practice | | | Anamorph/Te | Etiology | | and | | | leomorph) | | | Chemical | | | | | | Control | +=============+=============+=============+=============+=============+ | **Red rot** | Colletotric | D: | Conidia or | \- | | | hum | Ascomycota | ascospores | Resistant | | | falcatum | C: | (from | varieties - | | | (Teleomorph | Sordariomyc | infected | Hot water | | | : | etes | debris | treatment | | | Glomerella | O: | reach | of setts | | | tucumanensi | Glomerellal | healthy | (52°C for | | | s, | es | plant | 30 min) - | | | Syn: | F: | through | Chemical: | | | Physalospor | Glomerellac | rain splash | Propiconazo | | | a | eae | or wind) | le | | | tucumanensi | **Hemibiotr | infect | (0.1%) as | | | s) | ophic | stalks → | sett | | | | fungus** | red lesions | treatment | | | | | form in | | | | | | internal | | | | | | tissues → | | | | | | acervuli | | | | | | develop on | | | | | | stalk | | | | | | surface → | | | | | | conidia | | | | | | cause | | | | | | secondary | | | | | | infections | | | | | | → pathogen | | | | | | overwinters | | | | | | in plant | | | | | | debris and | | | | | | soil. | | +-------------+-------------+-------------+-------------+-------------+ | **Smut** | Sporisorium | D: | Teliospores | \- Rogue | | | scitamineum | Basidiomyco | (from soil | out and | | | (Syn: | ta | or air | destroy | | | Ustilago | C: | reach buds | infected | | | scitaminea) | Ustilaginom | through | clumps - | | | | ycetes | wind) | Hot water | | | | O: | germinate | treatment | | | | Ustilaginal | and infect | of setts | | | | es | buds → | (52°C for | | | | F: | systemic | 30 min) - | | | | Ustilaginac | growth → | Chemical: | | | | eae | whip-like | Triadimefon | | | | | sori emerge | (0.1%) as | | | | **Biotrophi | from | sett | | | | c | terminal | treatment | | | | fungus** | buds → | | | | | | teliospores | | | | | | disperse | | | | | | and | | | | | | overwinter | | | | | | in soil and | | | | | | on plant | | | | | | debris. | | +-------------+-------------+-------------+-------------+-------------+ | **Wilt** | Fusarium | D: | Conidia or | \- | | | sacchari | Ascomycota | ascospores | Disease-fre | | | (Teleomorph | C: | (from soil | e | | | : | Sordariomyc | reach roots | setts - | | | Gibberella | etes | through | Crop | | | fujikuroi, | O: | irrigation | rotation - | | | Syn: | Hypocreales | water) | Chemical: | | | Fusarium | F: | infect | Carbendazim | | | moniliforme | Nectriaceae | roots → | (0.1%) as | | | ) | | colonize | soil drench | | | | **Facultati | vascular | | | | | ve | tissues → | | | | | parasitic | wilting and | | | | | fungus** | drying of | | | | | | leaves → | | | | | | fungus | | | | | | produces | | | | | | conidia on | | | | | | infected | | | | | | tissues → | | | | | | pathogen | | | | | | overwinters | | | | | | in soil and | | | | | | plant | | | | | | debris. | | +-------------+-------------+-------------+-------------+-------------+ | **Grassy | Phytoplasma | Kingdom: | Phytoplasma | \- | | shoot** | (16SrXI | Bacteria P: | s | Disease-fre | | | group) | Tenericutes | (transmitte | e | | | | C: | d | planting | | | | Mollicutes | by | material - | | | | O: | leafhopper | Control of | | | | Acholeplasm | vectors) | insect | | | | atales | infect | vectors - | | | | F: | phloem → | Rogue out | | | | Acholeplasm | systemic | infected | | | | ataceae | spread → | plants | | | | | proliferati | | | | | **Obligate | on | | | | | intracellul | of thin, | | | | | ar | grassy | | | | | bacterium** | tillers → | | | | | | phytoplasma | | | | | | s | | | | | | overwinter | | | | | | in infected | | | | | | ratoons and | | | | | | alternate | | | | | | hosts. | | +-------------+-------------+-------------+-------------+-------------+ | **Ratoon | Leifsonia | Kingdom: | Bacteria | \- Hot | | stunting** | xyli subsp. | Bacteria P: | (from | water | | | xyli (Syn: | Actinobacte | infected | treatment | | | Clavibacter | ria | setts or | of setts | | | xyli subsp. | C: | contaminate | (50°C for 2 | | | xyli) | Actinobacte | d | hours) - | | | | ria | tools) | Disinfectio | | | | O: | enter | n | | | | Micrococcal | through | of cutting | | | | es | cuts → | tools - | | | | F: | colonize | Disease-fre | | | | Microbacter | xylem | e | | | | iaceae | vessels → | planting | | | | | stunting of | material | | | | **Gram-posi | ratoon | | | | | tive | crops → | | | | | bacterium** | bacteria | | | | | | overwinter | | | | | | in infected | | | | | | setts and | | | | | | ratoon | | | | | | stubbles. | | +-------------+-------------+-------------+-------------+-------------+ | **Pokkah | Fusarium | D: | Conidia or | \- | | Boeng** | verticillio | Ascomycota | ascospores | Resistant | | | ides | C: | (from soil | varieties - | | | (Teleomorph | Sordariomyc | or air | Balanced | | | : | etes | reach young | fertilizati | | | Gibberella | O: | leaves | on | | | fujikuroi, | Hypocreales | through | - Chemical: | | | Syn: | F: | wind) | Propiconazo | | | Fusarium | Nectriaceae | infect | le | | | moniliforme | **Facultati | young | (0.1%) at | | | ) | ve | leaves → | early | | | | parasitic | chlorotic | disease | | | | fungus** | areas and | onset | | | | | malformed | | | | | | leaves → | | | | | | necrosis | | | | | | and "top | | | | | | rot" in | | | | | | severe | | | | | | cases → | | | | | | fungus | | | | | | produces | | | | | | conidia on | | | | | | infected | | | | | | tissues → | | | | | | pathogen | | | | | | overwinters | | | | | | (in soil | | | | | | and plant | | | | | | debris). | | +-------------+-------------+-------------+-------------+-------------+ Sunflower Disease Name Causal Organism (Synonyms, Anamorph/Teleomorph) Systematic Position and Etiology Concise Disease Cycle Important Management Practice and Chemical Control -------------------------- ----------------------------------------------------------------- ------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------------------ **Sclerotinia stem rot** Sclerotinia sclerotiorum (Teleomorph: Whetzelinia sclerotiorum) D: Ascomycota C: Leotiomycetes O: Helotiales F: Sclerotiniaceae Etiology: Necrotrophic fungus Sclerotia (in soil) germinate to produce apothecia → ascospores (released from apothecia reach plants through wind) infect flowers or leaves → mycelium grows into stem → watery soft rot and white mycelium on stem → sclerotia form inside stem → sclerotia overwinter in soil and plant debris. \- Crop rotation (non-host crops) - Wider plant spacing (better air circulation) - Chemical: Carbendazim (0.1%) at flowering **Alternaria blight** Alternaria helianthi (Syn: Helminthosporium helianthi) D: Ascomycota C: Dothideomycetes O: Pleosporales F: Pleosporaceae Etiology: Necrotrophic fungus Conidia (from infected crop debris reach healthy plants through wind or rain splash) infect leaves → dark brown, circular to irregular lesions form on leaves → lesions expand, **coalesce** → severe infection leads to defoliation → conidia produced on lesions cause secondary infections → pathogen overwinters on crop debris and volunteer plants. \- Disease-resistant hybrids - Proper crop rotation - Chemical: Mancozeb (0.25%) at first sign of disease. Mustard Disease Name Causal Organism (Synonyms, Anamorph/Teleomorph) Systematic Position and Etiology Concise Disease Cycle Important Management Practice and Chemical Control -------------------------- ----------------------------------------------------------------- ------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------------------------------------------------- **Alternaria blight** Alternaria brassicae (No known teleomorph) D: Ascomycota C: Dothideomycetes O: Pleosporales F: Pleosporaceae Etiology: Necrotrophic fungus Conidia (from infected crop debris reach healthy plants through wind) infect leaves → circular, dark brown spots with concentric rings form on leaves, stems, and pods → lesions expand and coalesce → conidia produced on lesions cause secondary infections → pathogen overwinters (on crop debris and seed). \- Disease-resistant varieties - Crop rotation (non-cruciferous) - Chemical: Mancozeb (0.25%) at first sign of disease **White rust** Albugo candida (Syn: Cystopus candidus) D: Oomycota C: Oomycetes O: Albuginales F: Albuginaceae Etiology: Biotrophic oomycete Zoosporangia (from infected plant debris reach healthy plants through rain splash or wind) release zoospores → zoospores infect leaves → white, blister-like pustules form on leaves, stems, and inflorescences → oospores form in infected tissues → oospores overwinter (in soil and plant debris). \- Resistant varieties - Early sowing (escape favorable conditions) - Chemical: Metalaxyl + Mancozeb (0.2%) at first sign of disease **Downy mildew** Hyaloperonospora parasitica (Syn: Peronospora parasitica) D: Oomycota C: Oomycetes O: Peronosporales F: Peronosporaceae Etiology: Biotrophic oomycete Oospores (in soil or plant debris) germinate → zoospores released infect seedlings through roots or cotyledons → systemic infection → conidiophores emerge through stomata, producing conidia → conidia cause secondary infections → oospores form in infected tissues and overwinter (in soil and plant debris). \- Disease-free seeds - Proper drainage - Chemical: Metalaxyl + Mancozeb (0.2%) as seed treatment and foliar spray **Sclerotinia stem rot** Sclerotinia sclerotiorum (Teleomorph: Whetzelinia sclerotiorum) D: Ascomycota C: Leotiomycetes O: Helotiales F: Sclerotiniaceae Etiology: Necrotrophic fungus Sclerotia (in soil) germinate to produce apothecia → ascospores (released from apothecia reach plants through wind) infect flowers or leaves → mycelium grows into stem → watery soft rot and white mycelium on stem → sclerotia form inside stem → sclerotia overwinter (in soil and plant debris). \- Crop rotation (non-host crops) - Wider plant spacing (better air circulation) - Chemical: Carbendazim (0.1%) at flowering Gram Disease Name Causal Organism (Synonyms, Anamorph/Teleomorph) Systematic Position and Etiology Concise Disease Cycle Important Management Practice and Chemical Control ---------------------- ------------------------------------------------------- ---------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- **Fusarium wilt** Fusarium oxysporum f. sp. ciceris D: Ascomycota C: Sordariomycetes O: Hypocreales F: Nectriaceae Etiology: Soil-borne vascular wilt fungus Chlamydospores (from soil reach roots through irrigation water) germinate and infect roots → mycelium colonizes vascular tissue → wilting symptoms appear → fungus produces microconidia, macroconidia, and chlamydospores → chlamydospores overwinter (in soil and plant debris). \- Crop rotation (non-host crops, 3-4 years) - Use of resistant varieties - Note: Chemical control generally ineffective once established **Grey mould** Botrytis cinerea (Teleomorph: Botryotinia fuckeliana) D: Ascomycota C: Leotiomycetes O: Helotiales F: Sclerotiniaceae Etiology: Necrotrophic fungus Conidia (from infected plant debris reach healthy plant through wind and rain splash) infect leaves and stems → grey, fuzzy growth appears on infected tissues → sclerotia form → sclerotia and mycelium overwinter (in plant debris). \- Wider plant spacing (improve air circulation) - Chemical: Carbendazim (0.1%) or Iprodione (0.1%) at first sign of disease (repeat at 10-15 day intervals if needed) **Ascochyta blight** Ascochyta rabiei (Teleomorph: Didymella rabiei) D: Ascomycota C: Dothideomycetes O: Pleosporales F: Didymellaceae Etiology: Necrotrophic fungus Pycnidiospores or ascospores (from infected seed or plant debris reach healthy plant through rain splash or wind) infect leaves, stems, and pods → circular lesions with concentric rings of pycnidia form → pycnidiospores cause secondary infections → fungus overwinters as mycelium (in seed) or pseudothecia (on crop debris). \- Certified disease-free seeds - Seed treatment: Thiram + Carbendazim (2g + 1g/kg seed) - Foliar spray: Chlorothalonil (0.2%) or Mancozeb (0.2%) at first sign of disease (repeat at 10-14 day intervals if needed) Lentil Disease Name Causal Organism (Synonyms, Anamorph/Teleomorph) Systematic Position and Etiology Concise Disease Cycle Important Management Practice and Chemical Control ------------------- ------------------------------------------------- ---------------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ **Rust** Uromyces viciae-fabae (Syn: Uromyces fabae) D: Basidiomycota C: Pucciniomycetes O: Pucciniales F: Pucciniaceae Etiology: Obligate biotrophic fungus Urediniospores (from infected plant debris or alternate hosts reach healthy plant through wind) infect leaves → pustules form on leaves and stems → teliospores form late in the season → urediniospores and teliospores overwinter (on plant debris or alternate hosts). \- Early sowing (avoid favorable rust conditions) - Remove/destroy crop residues after harvest - Chemical: Mancozeb (0.2%) or Chlorothalonil (0.2%) at first sign of disease (repeat at 10-14 day intervals if needed) **Fusarium wilt** Fusarium oxysporum f. sp. lentis D: Ascomycota C: Sordariomycetes O: Hypocreales F: Nectriaceae Etiology: Soil-borne vascular wilt fungus Chlamydospores (from soil reach roots through irrigation water or root contact) germinate and infect roots → mycelium colonizes vascular tissue → wilting symptoms appear → fungus produces microconidia, macroconidia, and chlamydospores → chlamydospores overwinter (in soil and plant debris). \- Crop rotation (non-host crops, 4-5 years) - Use of resistant varieties - Soil solarization (severely infested fields) - Note: Chemical control generally ineffective once established Cotton Disease Name Causal Organism (Synonyms, Anamorph/Teleomorph) Systematic Position and Etiology Concise Disease Cycle Important Management Practice and Chemical Control ----------------------------------- ------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- **Anthracnose** Glomerella gossypii (Anamorph: Colletotrichum gossypii) D: Ascomycota C: Sordariomycetes O: Glomerellales F: Glomerellaceae Etiology: Necrotrophic fungus Conidia (from infected plant debris reach healthy plant through rain splash or wind) infect seedlings, leaves, and bolls → sunken lesions form on infected tissues → acervuli with setae produce conidia → perithecia may form later → fungus overwinters (in infected seeds and plant debris). \- Acid-delinted, fungicide-treated seeds - Crop rotation (non-host crops) - Chemical: Seed treatment (Carboxin + Thiram, 2g/kg seed) - Foliar spray: Carbendazim (0.1%) or Thiophanate-methyl (0.1%) at first sign of disease **Fusarium wilt** Fusarium oxysporum f. sp. vasinfectum D: Ascomycota C: Sordariomycetes O: Hypocreales F: Nectriaceae Etiology: Soil-borne vascular wilt fungus Chlamydospores (from soil reach roots through irrigation water or root contact) germinate and infect roots → mycelium colonizes vascular tissue → wilting symptoms appear → fungus produces microconidia, macroconidia, and chlamydospores → chlamydospores overwinter (in soil and plant debris). \- Use of resistant varieties - Crop rotation (non-host crops, 3-4 years) - Soil solarization (severely infested fields) - Note: Chemical control generally ineffective once established **Black arm (Angular leaf spot)** Xanthomonas citri pv. malvacearum (Syn: X. axonopodis pv. malvacearum, X. campestris pv. malvacearum) D: Proteobacteria C: Gammaproteobacteria O: Xanthomonadales F: Xanthomonadaceae Etiology: Gram-negative bacterium Bacteria (from infected seeds or plant debris reach healthy plant through rain splash or wind-driven rain) enter through stomata or wounds → water-soaked lesions appear on leaves, stems, and bolls → lesions become angular and dark → bacteria ooze from lesions → bacteria overwinter (in infected seeds and plant debris). \- Certified disease-free seeds - Crop rotation (non-host crops) - Avoid overhead irrigation - Chemical: Seed treatment (Streptomycin, 2.5g/kg seed) - Foliar spray: Streptomycin (100 ppm) + Copper oxychloride (0.3%) at first sign of disease (repeat at 10-15 day intervals if needed) Pea Disease Name Causal Organism (Synonyms, Anamorph/Teleomorph) Systematic Position and Etiology Concise Disease Cycle Important Management Practice and Chemical Control -------------------- ------------------------------------------------- --------------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- **Downy mildew** Peronospora viciae f. sp. pisi D: Oomycota C: Oomycetes O: Peronosporales F: Peronosporaceae Etiology: Obligate biotrophic oomycete Oospores (from soil or plant debris reach healthy plant through rain splash) germinate and infect leaves → mycelia grow intercellularly → chlorotic patches appear on upper leaf surface → sporangiophores emerge through stomata forming greyish-purple downy patches on lower leaf surface → sporangia disperse (by wind) to cause secondary infections → oospores form in infected tissues and overwinter in soil and plant debris. \- Use of resistant varieties - Crop rotation (non-host crops, 3-4 years) - Improve field drainage - Chemical: Metalaxyl + Mancozeb (0.2%) at first sign of disease (repeat at 10-14 day intervals if needed) **Powdery mildew** Erysiphe pisi (Syn: Erysiphe polygoni) D: Ascomycota C: Leotiomycetes O: Erysiphales F: Erysiphaceae Etiology: Obligate biotrophic fungus Conidia (from infected plant debris reach healthy plant through wind) infect leaves and stems → white powdery growth appears on leaf surfaces → conidia produced for secondary spread → cleistothecia form and overwinter (on plant debris). \- Plant early-maturing varieties - Avoid excessive nitrogen fertilization - Maintain proper plant spacing for good air circulation - Chemical: Sulfur (0.2%) or Triadimefon (0.1%) at first sign of disease (repeat at 10-14 day intervals if needed) **Rust** Uromyces pisi-sativi (Syn: Uromyces fabae) D: Basidiomycota C: Pucciniomycetes O: Pucciniales F: Pucciniaceae Etiology: Obligate biotrophic fungus Urediniospores (from infected plant debris or alternate hosts reach healthy plant through wind) infect leaves → pustules form on leaves and stems → teliospores form late in the season → urediniospores and teliospores overwinter (on plant debris or alternate hosts). \- Use of resistant varieties - Early sowing (avoid favorable rust conditions) - Remove/destroy crop residues after harvest - Chemical: Mancozeb (0.2%) or Chlorothalonil (0.2%) at first sign of disease (repeat at 10-14 day intervals if needed)